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  • 1. Ackley, K.
    et al.
    Amati, L.
    Barbieri, C.
    Bauer, F. E.
    Benetti, S.
    Bernardini, M. G.
    Bhirombhakdi, K.
    Botticella, M. T.
    Branchesi, M.
    Brocato, E.
    Bruun, S. H.
    Bulla, Mattia
    Stockholms universitet, Nordiska institutet för teoretisk fysik (Nordita).
    Campana, S.
    Cappellaro, E.
    Castro-Tirado, A. J.
    Chambers, K. C.
    Chaty, S.
    Chen, Ting-Wan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Max-Planck-Institut für Extraterrestrische Physik, Germany.
    Ciolfi, R.
    Coleiro, A.
    Copperwheat, C. M.
    Covino, S.
    Cutter, R.
    D'Ammando, F.
    D'Avanzo, P.
    De Cesare, G.
    D'Elia, V.
    Della Valle, M.
    Denneau, L.
    De Pasquale, M.
    Dhillon, V. S.
    Dyer, M. J.
    Elias-Rosa, N.
    Evans, P. A.
    Eyles-Ferris, R. A. J.
    Fiore, A.
    Fraser, M.
    Fruchter, A. S.
    Fynbo, J. P. U.
    Galbany, L.
    Gall, C.
    Galloway, D. K.
    Getman, F.
    Ghirlanda, G.
    Gillanders, J. H.
    Gomboc, A.
    Gompertz, B. P.
    Gonzalez-Fernandez, C.
    Gonzalez-Gaitan, S.
    Grado, A.
    Greco, G.
    Gromadzki, M.
    Groot, P. J.
    Gutierrez, C. P.
    Heikkila, T.
    Heintz, K. E.
    Hjorth, J.
    Hu, Y.-D.
    Huber, M. E.
    Inserra, C.
    Izzo, L.
    Japelj, J.
    Jerkstrand, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Jin, Z. P.
    Jonker, P. G.
    Kankare, E.
    Kann, D. A.
    Kennedy, M.
    Kim, S.
    Klose, S.
    Kool, Erik C.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kotak, R.
    Kuncarayakti, H.
    Lamb, G. P.
    Leloudas, G.
    Levan, A. J.
    Longo, F.
    Lowe, T. B.
    Lyman, J. D.
    Magnier, E.
    Maguire, K.
    Maiorano, E.
    Mandel, I.
    Mapelli, M.
    Mattila, S.
    McBrien, O. R.
    Melandri, A.
    Michalowski, M. J.
    Milvang-Jensen, B.
    Moran, S.
    Nicastro, L.
    Nicholl, M.
    Nicuesa Guelbenzu, A.
    Nuttal, L.
    Oates, S. R.
    O'Brien, P. T.
    Onori, F.
    Palazzi, E.
    Patricelli, B.
    Perego, A.
    Torres, M. A. P.
    Perley, D. A.
    Pian, E.
    Pignata, G.
    Piranomonte, S.
    Poshyachinda, S.
    Possenti, A.
    Pumo, M. L.
    Quirola-Vasquez, J.
    Ragosta, F.
    Ramsay, G.
    Rau, A.
    Rest, A.
    Reynolds, T. M.
    Rosetti, S. S.
    Rossi, A.
    Rosswog, Stephan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Sabha, N. B.
    Sagués Carracedo, Ana
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Salafia, O. S.
    Salmon, L.
    Salvaterra, R.
    Savaglio, S.
    Sbordone, L.
    Schady, P.
    Schipani, P.
    Schultz, A. S. B.
    Schweyer, Tassilo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Max-Planck-Institut für Extraterrestrische Physik, Germany.
    Smartt, S. J.
    Smith, K. W.
    Smith, M.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Srivastav, S.
    Stanway, E. R.
    Starling, R. L. C.
    Steeghs, D.
    Stratta, G.
    Stubbs, C. W.
    Tanvir, N. R.
    Testa, V.
    Thrane, E.
    Tonry, J. L.
    Turatto, M.
    Ulaczyk, K.
    van der Horst, A. J.
    Vergani, S. D.
    Walton, N. A.
    Watson, D.
    Wiersema, K.
    Wiik, K.
    Wyrzykowski, L.
    Yang, Sheng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Yi, S.-X.
    Young, D. R.
    Observational constraints on the optical and near-infrared emission from the neutron star-black hole binary merger candidate S190814bv2020Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 643, artikkel-id A113Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Context. Gravitational wave (GW) astronomy has rapidly reached maturity, becoming a fundamental observing window for modern astrophysics. The coalescences of a few tens of black hole (BH) binaries have been detected, while the number of events possibly including a neutron star (NS) is still limited to a few. On 2019 August 14, the LIGO and Virgo interferometers detected a high-significance event labelled S190814bv. A preliminary analysis of the GW data suggests that the event was likely due to the merger of a compact binary system formed by a BH and a NS.

    Aims. In this paper, we present our extensive search campaign aimed at uncovering the potential optical and near infrared electromagnetic counterpart of S190814bv. We found no convincing electromagnetic counterpart in our data. We therefore use our non-detection to place limits on the properties of the putative outflows that could have been produced by the binary during and after the merger.

    Methods. Thanks to the three-detector observation of S190814bv, and given the characteristics of the signal, the LIGO and Virgo Collaborations delivered a relatively narrow localisation in low latency - a 50% (90%) credible area of 5 deg(2) (23 deg(2)) - despite the relatively large distance of 26752 Mpc. ElectromagNetic counterparts of GRAvitational wave sources at the VEry Large Telescope collaboration members carried out an intensive multi-epoch, multi-instrument observational campaign to identify the possible optical and near infrared counterpart of the event. In addition, the ATLAS, GOTO, GRAWITA-VST, Pan-STARRS, and VINROUGE projects also carried out a search on this event. In this paper, we describe the combined observational campaign of these groups.

    Results. Our observations allow us to place limits on the presence of any counterpart and discuss the implications for the kilonova (KN), which was possibly generated by this NS-BH merger, and for the strategy of future searches. The typical depth of our wide-field observations, which cover most of the projected sky localisation probability (up to 99.8%, depending on the night and filter considered), is r similar to 22 (resp. K similar to 21) in the optical (resp. near infrared). We reach deeper limits in a subset of our galaxy-targeted observations, which cover a total similar to 50% of the galaxy-mass-weighted localisation probability. Altogether, our observations allow us to exclude a KN with large ejecta mass M greater than or similar to 0.1 M-circle dot to a high (> 90%) confidence, and we can exclude much smaller masses in a sub-sample of our observations. This disfavours the tidal disruption of the neutron star during the merger.

    Conclusions. Despite the sensitive instruments involved in the campaign, given the distance of S190814bv, we could not reach sufficiently deep limits to constrain a KN comparable in luminosity to AT 2017gfo on a large fraction of the localisation probability. This suggests that future (likely common) events at a few hundred megaparsecs will be detected only by large facilities with both a high sensitivity and large field of view. Galaxy-targeted observations can reach the needed depth over a relevant portion of the localisation probability with a smaller investment of resources, but the number of galaxies to be targeted in order to get a fairly complete coverage is large, even in the case of a localisation as good as that of this event.

  • 2. Adams, S. M.
    et al.
    Blagorodnova, N.
    Kasliwal, M. M.
    Amanullah, Rahman
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Barlow, T.
    Bue, B.
    Bulla, Mattia
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Cao, Y.
    Cenko, S. B.
    Cook, D. O.
    Ferretti, Raphael
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Fox, O. D.
    Fremling, Christoffer
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Gezari, S.
    Goobar, Ariel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Ho, A. Y. Q.
    Hung, Tiara
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Karamehmetoglu, Emir
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kulkarni, S. R.
    Kupfer, T.
    Laher, R. R.
    Masci, F. J.
    Miller, A. A.
    Neill, J. D.
    Nugent, P. E.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Taddia, Francesco
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Walters, R.
    iPTF Survey for Cool Transients2018Inngår i: Publications of the Astronomical Society of the Pacific, ISSN 0004-6280, E-ISSN 1538-3873, Vol. 130, nr 985, artikkel-id 034202Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We performed a wide-area (2000 deg2) g and I band experiment as part of a two month extension to the Intermediate Palomar Transient Factory. We discovered 36 extragalactic transients including iPTF17lf, a highly reddened local SN Ia, iPTF17bkj, a new member of the rare class of transitional Ibn/IIn supernovae, and iPTF17be, a candidate luminous blue variable outburst. We do not detect any luminous red novae and place an upper limit on their rate. We show that adding a slow-cadence I band component to upcoming surveys such as the Zwicky Transient Facility will improve the photometric selection of cool and dusty transients.

  • 3. Agudo, I.
    et al.
    Chen, T. -W.
    Stockholm Univ, Oskar Klein Ctr, Dept Astron, AlbaNova, Stockholm, Sweden.
    Kool, Erik C.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Schulze, Steve
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Yang, S.
    Stockholm Univ, Oskar Klein Ctr, Dept Astron, AlbaNova, Stockholm, Sweden.
    Young, D. R.
    Panning for gold, but finding helium: Discovery of the ultra-stripped supernova SN 2019wxt from gravitational-wave follow-up observations2023Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 675, artikkel-id A201Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present the results from multi-wavelength observations of a transient discovered during an intensive follow-up campaign of S191213g, a gravitational wave (GW) event reported by the LIGO-Virgo Collaboration as a possible binary neutron star merger in a low latency search. This search yielded SN 2019wxt, a young transient in a galaxy whose sky position (in the 80% GW contour) and distance (similar to SIM;150 Mpc) were plausibly compatible with the localisation uncertainty of the GW event. Initially, the transient's tightly constrained age, its relatively faint peak magnitude (M-i similar to -16.7 mag), and the r-band decline rate of similar to 1 mag per 5 days appeared suggestive of a compact binary merger. However, SN 2019wxt spectroscopically resembled a type Ib supernova, and analysis of the optical-near-infrared evolution rapidly led to the conclusion that while it could not be associated with S191213g, it nevertheless represented an extreme outcome of stellar evolution. By modelling the light curve, we estimated an ejecta mass of only similar to 0.1 M circle dot, with Ni-56 comprising similar to 20% of this. We were broadly able to reproduce its spectral evolution with a composition dominated by helium and oxygen, with trace amounts of calcium. We considered various progenitor channels that could give rise to the observed properties of SN 2019wxt and concluded that an ultra-stripped origin in a binary system is the most likely explanation. Disentangling genuine electromagnetic counterparts to GW events from transients such as SN 2019wxt soon after discovery is challenging: in a bid to characterise this level of contamination, we estimated the rate of events with a volumetric rate density comparable to that of SN 2019wxt and found that around one such event per week can occur within the typical GW localisation area of O4 alerts out to a luminosity distance of 500 Mpc, beyond which it would become fainter than the typical depth of current electromagnetic follow-up campaigns.

  • 4.
    Ahrens, Maryon
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Conrad, Jan M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Dumm, Jonathan P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Finley, Chad
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Flis, Samuel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hultqvist, Klas
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Walck, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Zoll, Marcel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Meyer, Manuel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stanford University, USA.
    Rosswog, Stephan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Feindt, Ulrich
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Goobar, Ariel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Barbarino, Cristina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bulla, Mattia
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Roy, Rupak
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Taddia, Francesco
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Farnier, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Linnaeus University, Sweden.
    Morå, Knut
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wagner, Robert M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Multi-messenger Observations of a Binary Neutron Star Merger2017Inngår i: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 848, nr 2, artikkel-id L12Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of similar to 1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg(2) at a luminosity distance of 40(-8)(+8) Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 M-circle dot. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at similar to 40 Mpc) less than 11 hours after the merger by the One-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over similar to 10 days. Following early non-detections, X-ray and radio emission were discovered at the transient's position similar to 9 and similar to 16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta.

  • 5. Ahumada, Tomas
    et al.
    Anand, Shreya
    Coughlin, Michael W.
    Andreoni, Igor
    Kool, Erik C.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kumar, Harsh
    Reusch, Simeon
    Sagués Carracedo, Ana
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Stein, Robert
    Cenko, S. Bradley
    Kasliwal, Mansi M.
    Singer, Leo P.
    Dunwoody, Rachel
    Mangan, Joseph
    Bhalerao, Varun
    Bulla, Mattia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Burns, Eric
    Graham, Matthew J.
    Kaplan, David L.
    Perley, Daniel
    Almualla, Mouza
    Bloom, Joshua S.
    Cunningham, Virginia
    De, Kishalay
    Gatkine, Pradip
    Ho, Anna Y. Q.
    Karambelkar, Viraj
    Kong, Albert K. H.
    Yao, Yuhan
    Anupama, G. C.
    Barway, Sudhanshu
    Ghosh, Shaon
    Itoh, Ryosuke
    McBreen, Sheila
    Bellm, Eric C.
    Fremling, Christoffer
    Laher, Russ R.
    Mahabal, Ashish A.
    Riddle, Reed L.
    Rosnet, Philippe
    Rusholme, Ben
    Smith, Roger
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bissaldi, Elisabetta
    Fletcher, Corinne
    Hamburg, Rachel
    Mailyan, Bagrat
    Malacaria, Christian
    Roberts, Oliver
    In Search of Short Gamma-Ray Burst Optical Counterparts with the Zwicky Transient Facility2022Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 932, nr 1, artikkel-id 40Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Fermi Gamma-ray Burst Monitor (GBM) triggers on-board in response to ∼40 short gamma-ray bursts (SGRBs) per year; however, their large localization regions have made the search for optical counterparts a challenging endeavour. We have developed and executed an extensive program with the wide field of view of the Zwicky Transient Facility (ZTF) camera, mounted on the Palomar 48 inch Oschin telescope (P48), to perform target-of-opportunity (ToO) observations on 10 Fermi-GBM SGRBs during 2018 and 2020–2021. Bridging the large sky areas with small field-of-view optical telescopes in order to track the evolution of potential candidates, we look for the elusive SGRB afterglows and kilonovae (KNe) associated with these high-energy events. No counterpart has yet been found, even though more than 10 ground-based telescopes, part of the Global Relay of Observatories Watching Transients Happen (GROWTH) network, have taken part in these efforts. The candidate selection procedure and the follow-up strategy have shown that ZTF is an efficient instrument for searching for poorly localized SGRBs, retrieving a reasonable number of candidates to follow up and showing promising capabilities as the community approaches the multi-messenger era. Based on the median limiting magnitude of ZTF, our searches would have been able to retrieve a GW170817-like event up to ∼200 Mpc and SGRB afterglows to z = 0.16 or 0.4, depending on the assumed underlying energy model. Future ToOs will expand the horizon to z = 0.2 and 0.7, respectively.

  • 6. Alp, Dennis
    et al.
    Larsson, Josefin
    Fransson, Claes
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Indebetouw, Remy
    Jerkstrand, Anders
    Ahola, Antero
    Burrows, David
    Challis, Peter
    Cigan, Phil
    Cikota, Aleksandar
    Kirshner, Robert P.
    van Loon, Jacco Th.
    Mattila, Seppo
    Ng, C. -Y.
    Park, Sangwook
    Spyromilio, Jason
    Woosley, Stan
    Baes, Maarten
    Bouchet, Patrice
    Chevalier, Roger
    Frank, Kari A.
    Gaensler, B. M.
    Gomez, Haley
    Janka, Hans-Thomas
    Leibundgut, Bruno
    Lundqvist, Peter
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Marcaide, Jon
    Matsuura, Mikako
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Sonneborn, George
    Staveley-Smith, Lister
    Zanardo, Giovanna
    Gabler, Michael
    Taddia, Francesco
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wheeler, J. Craig
    The 30 Year Search for the Compact Object in SN 1987A2018Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 864, nr 2, artikkel-id 174Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Despite more than 30 years of searching, the compact object in Supernova (SN) 1987A has not yet been detected. We present new limits on the compact object in SN 1987A using millimeter, near-infrared, optical, ultraviolet, and X-ray observations from ALMA, VLT, HST, and Chandra. The limits are approximately 0.1 mJy (0.1 x 10(-26) erg s(-1) cm(-2) Hz(-1)) at 213 GHz, 1 L-circle dot (6 x 10(-29) erg s(-1) cm(-2) Hz(-1)) in the optical if our line of sight is free of ejecta dust, and 10(36) erg s(-1) (2 x 10(-30) erg s(-1) cm(-2) Hz(-1) ) in 2-10 keV X-rays. Our X-ray limits are an order of magnitude less constraining than previous limits because we use a more realistic ejecta absorption model based on three-dimensional neutrino-driven SN explosion models. The allowed bolometric luminosity of the compact object is 22 L-circle dot if our line of sight is free of ejecta dust, or 138L(circle dot) if dust-obscured. Depending on assumptions, these values limit the effective temperature of a neutron star (NS) to <4-8 MK and do not exclude models, which typically are in the range 3-4 MK. For the simplest accretion model, the accretion rate for an efficiency 77 is limited to <10(-11) eta(-1) M-circle dot yr(-1), which excludes most predictions. For pulsar activity modeled by a rotating magnetic dipole in vacuum, the limit on the magnetic field strength (B) for a given spin period (P) is B less than or similar to 10(14) P-2 G s(-2), which firmly excludes pulsars comparable to the Crab. By combining information about radiation reprocessing and geometry, we infer that the compact object is a dust-obscured thermally emitting NS, which may appear as a region of higher-temperature ejecta dust emission.

  • 7. Anand, Shreya
    et al.
    Barnes, Jennifer
    Yang, Sheng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Henan Academy of Sciences, Peopleʼs Republic of China.
    Kasliwal, Mansi M.
    Coughlin, Michael W.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    De, Kishalay
    Fremling, Christoffer
    Corsi, Alessandra
    Ho, Anna Y. Q.
    Balasubramanian, Arvind
    Omand, Conor M. B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Srinivasaragavan, Gokul P.
    Cenko, S. Bradley
    Ahumada, Tomás
    Andreoni, Igor
    Dahiwale, Aishwarya
    Das, Kaustav Kashyap
    Jencson, Jacob
    Karambelkar, Viraj
    Kumar, Harsh
    Metzger, Brian D.
    Perley, Daniel
    Sarin, Nikhil
    Stockholms universitet, Nordiska institutet för teoretisk fysik (Nordita). Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Schweyer, Tassilo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Schulze, Steve
    Sharma, Yashvi
    Sit, Tawny
    Stein, Robert
    Tartaglia, Leonardo
    Tinyanont, Samaporn
    Tzanidakis, Anastasios
    van Roestel, Jan
    Yao, Yuhan
    Bloom, Joshua S.
    Cook, David O.
    Dekany, Richard
    Graham, Matthew J.
    Groom, Steven L.
    Kaplan, David L.
    Masci, Frank J.
    Medford, Michael S.
    Riddle, Reed
    Zhang, Chaoran
    Collapsars as Sites of r-process Nucleosynthesis: Systematic Photometric Near-infrared Follow-up of Type Ic-BL Supernovae2024Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 962, nr 1, artikkel-id 68Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    One of the open questions following the discovery of GW170817 is whether neutron star (NS) mergers are the only astrophysical sites capable of producing r-process elements. Simulations have shown that 0.01–0.1 M of r-process material could be generated in the outflows originating from the accretion disk surrounding the rapidly rotating black hole that forms as a remnant to both NS mergers and collapsing massive stars associated with long-duration gamma-ray bursts (collapsars). The hallmark signature of r-process nucleosynthesis in the binary NS merger GW170817 was its long-lasting near-infrared (NIR) emission, thus motivating a systematic photometric study of the light curves of broad-lined stripped-envelope (Ic-BL) supernovae (SNe) associated with collapsars. We present the first systematic study of 25 SNe Ic-BL—including 18 observed with the Zwicky Transient Facility and 7 from the literature—in the optical/NIR bands to determine what quantity of r-process material, if any, is synthesized in these explosions. Using semi-analytic models designed to account for r-process production in SNe Ic-BL, we perform light curve fitting to derive constraints on the r-process mass for these SNe. We also perform independent light curve fits to models without the r-process. We find that the r-process-free models are a better fit to the light curves of the objects in our sample. Thus, we find no compelling evidence of r-process enrichment in any of our objects. Further high-cadence infrared photometric studies and nebular spectroscopic analysis would be sensitive to smaller quantities of r-process ejecta mass or indicate whether all collapsars are completely devoid of r-process nucleosynthesis.

  • 8. Anand, Shreya
    et al.
    Coughlin, Michael W.
    Kasliwal, Mansi M.
    Bulla, Mattia
    Stockholms universitet, Nordiska institutet för teoretisk fysik (Nordita).
    Ahumada, Tomás
    Sagués Carracedo, Ana
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Almualla, Mouza
    Andreoni, Igor
    Stein, Robert
    Foucart, Francois
    Singer, Leo P.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bellm, Eric C.
    Bolin, Bryce
    Caballero-García, M. D.
    Castro-Tirado, Alberto J.
    Cenko, S. Bradley
    De, Kishalay
    Dekany, Richard G.
    Duev, Dmitry A.
    Feeney, Michael
    Fremling, Christoffer
    Goldstein, Daniel A.
    Golkhou, V. Zach
    Graham, Matthew J.
    Guessoum, Nidhal
    Hankins, Matthew J.
    Hu, Youdong
    Kong, Albert K. H.
    Kool, Erik C.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kulkarni, S. R.
    Kumar, Harsh
    Laher, Russ R.
    Masci, Frank J.
    Mróz, Przemek
    Nissanke, Samaya
    Porter, Michael
    Reusch, Simeon
    Riddle, Reed
    Rosnet, Philippe
    Rusholme, Ben
    Serabyn, Eugene
    Sánchez-Ramírez, R.
    Rigault, Mickael
    Shupe, David L.
    Smith, Roger
    Soumagnac, Maayane T.
    Walters, Richard
    Valeev, Azamat F.
    Stockholms universitet, Nordiska institutet för teoretisk fysik (Nordita). California Institute of Technology, USA; Russian Academy of Sciences, Russia.
    Optical follow-up of the neutron star-black hole mergers S200105ae and S200115j2021Inngår i: Nature Astronomy, E-ISSN 2397-3366, Vol. 5, s. 46-53Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    LIGO and Virgo's third observing run revealed the first neutron star-black hole (NSBH) merger candidates in gravitational waves. These events are predicted to synthesize r-process elements(1,2)creating optical/near-infrared 'kilonova' emission. The joint gravitational wave and electromagnetic detection of an NSBH merger could be used to constrain the equation of state of dense nuclear matter(3), and independently measure the local expansion rate of the Universe(4). Here, we present the optical follow-up and analysis of two of the only three high-significance NSBH merger candidates detected to date, S200105ae and S200115j, with the Zwicky Transient Facility(5). The Zwicky Transient Facility observed similar to 48% of S200105ae and similar to 22% of S200115j's localization probabilities, with observations sensitive to kilonovae brighter than -17.5 mag fading at 0.5 mag d(-1)in the g- and r-bands; extensive searches and systematic follow-up of candidates did not yield a viable counterpart. We present state-of-the-art kilonova models tailored to NSBH systems that place constraints on the ejecta properties of these NSBH mergers. We show that with observed depths of apparent magnitude similar to 22 mag, attainable in metre-class, wide-field-of-view survey instruments, strong constraints on ejecta mass are possible, with the potential to rule out low mass ratios, high black hole spins and large neutron star radii.

  • 9.
    Anderson, Brandon
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Larsson, Stefan
    Li, L.
    Meyer, Manuel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Zimmer, Stephan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Ferretti, Raphael
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Rosswog, Stephan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    SUPPLEMENT: LOCALIZATION AND BROADBAND FOLLOW-UP OF THE GRAVITATIONAL-WAVE TRANSIENT GW150914 (2016, ApJL, 826, L13)2016Inngår i: Astrophysical Journal Supplement Series, ISSN 0067-0049, E-ISSN 1538-4365, Vol. 225, nr 1, artikkel-id 8Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This Supplement provides supporting material for Abbott et al. (2016a). We briefly summarize past electromagnetic (EM) follow-up efforts as well as the organization and policy of the current EM follow-up program. We compare the four probability sky maps produced for the gravitational-wave transient GW150914, and provide additional details of the EM follow-up observations that were performed in the different bands.

  • 10.
    Anderson, Brandon
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Meyer, Manuel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Ferretti, Raphael
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Zimmer, Stephan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Rosswog, Stephan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    LOCALIZATION AND BROADBAND FOLLOW-UP OF THE GRAVITATIONAL-WAVE TRANSIENT GW 1509142016Inngår i: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 826, nr 1, artikkel-id L13Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A gravitational-wave (GW) transient was identified in data recorded by the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) detectors on 2015 September 14. The event, initially designated G184098 and later given the name GW150914, is described in detail elsewhere. By prior arrangement, preliminary estimates of the time, significance, and sky location of the event were shared with 63 teams of observers covering radio, optical, near-infrared, X-ray, and gamma-ray wavelengths with ground- and space-based facilities. In this Letter we describe the low-latency analysis of the GW data and present the sky localization of the first observed compact binary merger. We summarize the follow-up observations reported by 25 teams via private Gamma-ray Coordinates Network circulars, giving an overview of the participating facilities, the GW sky localization coverage, the timeline, and depth of the observations. As this event turned out to be a binary black hole merger, there is little expectation of a detectable electromagnetic (EM) signature. Nevertheless, this first broadband campaign to search for a counterpart of an Advanced LIGO source represents a milestone and highlights the broad capabilities of the transient astronomy community and the observing strategies that have been developed to pursue neutron star binary merger events. Detailed investigations of the EM data and results of the EM follow-up campaign are being disseminated in papers by the individual teams.

  • 11. Anderson, P.
    et al.
    Dessart, L.
    Gutiérrez, C. P.
    Krühler, T.
    Galbany, L.
    Jerkstrand, A.
    Smartt, S. J.
    Contreras, C.
    Morrell, N.
    Phillips, M. M.
    Stritzinger, M. D.
    Hsiao, E. Y.
    González-Gaitán, S.
    Agliozzo, C.
    Castellón, S.
    Chambers, K. C.
    Chen, T. -W.
    Flewelling, H.
    Gonzalez, C.
    Hosseinzadeh, G.
    Huber, M.
    Fraser, M.
    Inserra, C.
    Kankare, E.
    Mattila, S.
    Magnier, E.
    Maguire, K.
    Lowe, T. B.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Sullivan, M.
    Young, D. R.
    Valenti, S.
    The lowest-metallicity type II supernova from the highest-mass red supergiant progenitor2018Inngår i: Nature Astronomy, E-ISSN 2397-3366, Vol. 2, nr 7, s. 574-579Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Red supergiants have been confirmed as the progenitor stars of the majority of hydrogen-rich type II supernovae(1). However, while such stars are observed with masses > 25 M-circle dot (ref. (2)), detections of > 18 M-circle dot progenitors remain elusive(1). Red supergiants are also expected to form at all metallicities, but discoveries of explosions from low-metallicity progenitors are scarce. Here, we report observations of the type II supernova, SN 2015bs, for which we infer a progenitor metallicity of <= 0.1 Z(circle dot) from comparison to photospheric-phase spectral models(3), and a zero-age main-sequence mass of 17-25 M-circle dot through comparison to nebular-phase spectral models(4,5). SN 2015bs displays a normal 'plateau' light-curve morphology, and typical spectral properties, implying a red supergiant progenitor. This is the first example of such a high-mass progenitor for a 'normal' type II supernova, suggesting a link between high-mass red supergiant explosions and low-metallicity progenitors.

  • 12. Andreoni, I.
    et al.
    Ackley, K.
    Cooke, J.
    Acharyya, A.
    Allison, J. R.
    Anderson, G. E.
    Ashley, M. C. B.
    Baade, D.
    Bailes, M.
    Bannister, K.
    Beardsley, A.
    Bessell, M. S.
    Bian, F.
    Bland, P. A.
    Boer, M.
    Booler, T.
    Brandeker, Alexis
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Brown, I. S.
    Buckley, D. A. H.
    Chang, S. -W.
    Coward, D. M.
    Crawford, S.
    Crisp, H.
    Crosse, B.
    Cucchiara, A.
    Cupak, M.
    de Gois, J. S.
    Deller, A.
    Devillepoix, H. A. R.
    Dobie, D.
    Elmer, E.
    Emrich, D.
    Farah, W.
    Farrell, T. J.
    Franzen, T.
    Gaensler, B. M.
    Galloway, D. K.
    Gendre, B.
    Giblin, T.
    Goobar, Ariel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Green, J.
    Hancock, P. J.
    Hartig, B. A. D.
    Howell, E. J.
    Horsley, L.
    Hotan, A.
    Howie, R. M.
    Hu, L.
    Hu, Y.
    James, C. W.
    Johnston, S.
    Johnston-Hollitt, M.
    Kaplan, D. L.
    Kasliwal, M.
    Keane, E. F.
    Kenney, D.
    Klotz, A.
    Lau, R.
    Laugier, R.
    Lenc, E.
    Li, X.
    Liang, E.
    Lidman, C.
    Luvaul, L. C.
    Lynch, C.
    Ma, B.
    Macpherson, D.
    Mao, J.
    McClelland, D. E.
    McCully, C.
    Moller, A.
    Morales, M. F.
    Morris, D.
    Murphy, T.
    Noysena, K.
    Onken, C. A.
    Orange, N. B.
    Oslowski, S.
    Pallot, D.
    Paxman, J.
    Potter, S. B.
    Pritchard, T.
    Raja, W.
    Ridden-Harper, R.
    Romero-Colmenero, E.
    Sadler, E. M.
    Sansom, E. K.
    Scalzo, R. A.
    Schmidt, B. P.
    Scott, S. M.
    Seghouani, N.
    Shang, Z.
    Shannon, R. M.
    Shao, L.
    Shara, M. M.
    Sharp, R.
    Sokolowski, M.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Staff, J.
    Steele, K.
    Sun, T.
    Suntzeff, N. B.
    Tao, C.
    Tingay, S.
    Towner, M. C.
    Thierry, P.
    Trott, C.
    Tucker, B. E.
    Vaisanen, P.
    Krishnan, V. Venkatraman
    Walker, M.
    Wang, L.
    Wang, X.
    Wayth, R.
    Whiting, M.
    Williams, A.
    Williams, T.
    Wolf, C.
    Wu, C.
    Wu, X.
    Yang, J.
    Yuan, X.
    Zhang, H.
    Zhou, J.
    Zovaro, H.
    Follow Up of GW170817 and Its Electromagnetic Counterpart by Australian-Led Observing Programmes2017Inngår i: Publications Astronomical Society of Australia, ISSN 1323-3580, E-ISSN 1448-6083, Vol. 34, artikkel-id e069Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    The discovery of the first electromagnetic counterpart to a gravitational wave signal has generated follow-up observations by over 50 facilities world-wide, ushering in the new era of multi-messenger astronomy. In this paper, we present follow-up observations of the gravitational wave event GW170817 and its electromagnetic counterpart SSS17a/DLT17ck (IAU label AT2017gfo) by 14 Australian telescopes and partner observatories as part of Australian-based and Australian-led research programs. We report early- to late-time multi-wavelength observations, including optical imaging and spectroscopy, mid-infrared imaging, radio imaging, and searches for fast radio bursts. Our optical spectra reveal that the transient source emission cooled from approximately 6 400 K to 2 100 K over a 7-d period and produced no significant optical emission lines. The spectral profiles, cooling rate, and photometric light curves are consistent with the expected outburst and subsequent processes of a binary neutron star merger. Star formation in the host galaxy probably ceased at least a Gyr ago, although there is evidence for a galaxy merger. Binary pulsars with short (100 Myr) decay times are therefore unlikely progenitors, but pulsars like PSR B1534+12 with its 2.7 Gyr coalescence time could produce such a merger. The displacement (similar to 2.2 kpc) of the binary star system from the centre of the main galaxy is not unusual for stars in the host galaxy or stars originating in the merging galaxy, and therefore any constraints on the kick velocity imparted to the progenitor are poor.

  • 13. Andreoni, Igor
    et al.
    Coughlin, Michael W.
    Kool, Erik C.
    Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Kasliwal, Mansi M.
    Kumar, Harsh
    Bhalerao, Varun
    Carracedo, Ana Sagués
    Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Ho, Anna Y. Q.
    Pang, Peter T. H.
    Saraogi, Divita
    Sharma, Kritti
    Shenoy, Vedant
    Burns, Eric
    Ahumada, Tomás
    Anand, Shreya
    Singer, Leo P.
    Perley, Daniel A.
    De, Kishalay
    Fremling, U. C.
    Bellm, Eric C.
    Bulla, Mattia
    Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Crellin-Quick, Arien
    Dietrich, Tim
    Drake, Andrew
    Duev, Dmitry A.
    Goobar, Ariel
    Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Graham, Matthew J.
    Kaplan, David L.
    Kulkarni, S. R.
    Laher, Russ R.
    Mahabal, Ashish A.
    Shupe, David L.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Walters, Richard
    Yao, Yuhan
    Fast-transient Searches in Real Time with ZTFReST: Identification of Three Optically Discovered Gamma-Ray Burst Afterglows and New Constraints on the Kilonova Rate2021Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 918, nr 2, artikkel-id 63Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The most common way to discover extragalactic fast transients, which fade within a few nights in the optical, is via follow-up of gamma-ray burst and gravitational-wave triggers. However, wide-field surveys have the potential to identify rapidly fading transients independently of such external triggers. The volumetric survey speed of the Zwicky Transient Facility (ZTF) makes it sensitive to objects as faint and fast fading as kilonovae, the optical counterparts to binary neutron star mergers, out to almost 200 Mpc. We introduce an open-source software infrastructure, the ZTF REaltime Search and Triggering, ZTFReST, designed to identify kilonovae and fast transients in ZTF data. Using the ZTF alert stream combined with forced point-spread-function photometry, we have implemented automated candidate ranking based on their photometric evolution and fitting to kilonova models. Automated triggering, with a human in the loop for monitoring, of follow-up systems has also been implemented. In 13 months of science validation, we found several extragalactic fast transients independently of any external trigger, including two supernovae with post-shock cooling emission, two known afterglows with an associated gamma-ray burst (ZTF20abbiixp, ZTF20abwysqy), two known afterglows without any known gamma-ray counterpart (ZTF20aajnksq, ZTF21aaeyldq), and three new fast-declining sources (ZTF20abtxwfx, ZTF20acozryr, ZTF21aagwbjr) that are likely associated with GRB200817A, GRB201103B, and GRB210204A. However, we have not found any objects that appear to be kilonovae. We constrain the rate of GW170817-like kilonovae to R < 900 Gpc(-3) yr(-1) (95% confidence). A framework such as ZTFReST could become a prime tool for kilonova and fast-transient discovery with the Vera Rubin Observatory.

  • 14. Andreoni, Igor
    et al.
    Goldstein, Daniel A.
    Kasliwal, Mansi M.
    Nugent, Peter E.
    Zhou, Rongpu
    Newman, Jeffrey A.
    Bulla, Mattia
    Stockholms universitet, Nordiska institutet för teoretisk fysik (Nordita). Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Foucart, Francois
    Hotokezaka, Kenta
    Nakar, Ehud
    Nissanke, Samaya
    Raaijmakers, Geert
    Bloom, Joshua S.
    De, Kishalay
    Jencson, Jacob E.
    Ward, Charlotte
    Ahumada, Tomas
    Anand, Shreya
    Buckley, David A. H.
    Caballero-Garcia, Maria D.
    Castro-Tirado, Alberto J.
    Copperwheat, Christopher M.
    Coughlin, Michael W.
    Cenko, S. Bradley
    Gromadzki, Mariusz
    Hu, Youdong
    Karambelkar, Viraj R.
    Perley, Daniel A.
    Sharma, Yashvi
    Valeev, Azamat F.
    Cook, David O.
    Fremling, U. Christoffer
    Kumar, Harsh
    Taggart, Kirsty
    Bagdasaryan, Ashot
    Cooke, Jeff
    Dahiwale, Aishwarya
    Dhawan, Suhail
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Dobie, Dougal
    Gatkine, Pradip
    Golkhou, V. Zach
    Goobar, Ariel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Chaves, Andreas Guerra
    Hankins, Matthew
    Kaplan, David L.
    Kong, Albert K. H.
    Kool, Erik C.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Mohite, Siddharth
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Tzanidakis, Anastasios
    Webb, Sara
    Zhang, Keming
    GROWTH on S190814bv: Deep Synoptic Limits on the Optical/Near-infrared Counterpart to a Neutron Star-Black Hole Merger2020Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 890, nr 2, artikkel-id 131Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    On 2019 August 14, the Advanced LIGO and Virgo interferometers detected the high-significance gravitational wave (GW) signal S190814bv. The GW data indicated that the event resulted from a neutron star-black hole (NSBH) merger, or potentially a low-mass binary BH merger. Due to the low false-alarm rate and the precise localization (23 deg(2) at 90%), S190814bv presented the community with the best opportunity yet to directly observe an optical/near-infrared counterpart to an NSBH merger. To search for potential counterparts, the GROWTH Collaboration performed real-time image subtraction on six nights of public Dark Energy Camera images acquired in the 3 weeks following the merger, covering >98% of the localization probability. Using a worldwide network of follow-up facilities, we systematically undertook spectroscopy and imaging of optical counterpart candidates. Combining these data with a photometric redshift catalog, we ruled out each candidate as the counterpart to S190814bv and placed deep, uniform limits on the optical emission associated with S190814bv. For the nearest consistent GW distance, radiative transfer simulations of NSBH mergers constrain the ejecta mass of S190814bv to be M-ej < 0.04 M-circle dot at polar viewing angles, or M-ej < 0.03 M-circle dot if the opacity is kappa < 2 cm(2)g(-1). Assuming a tidal deformability for the NS at the high end of the range compatible with GW170817 results, our limits would constrain the BH spin component aligned with the orbital momentum to be chi < 0.7 for mass ratios Q < 6, with weaker constraints for more compact NSs.

  • 15. Andreoni, Igor
    et al.
    Kool, Erik C.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Sagués Carracedo, Ana
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kasliwal, Mansi M.
    Bulla, Mattia
    Stockholms universitet, Nordiska institutet för teoretisk fysik (Nordita).
    Ahumada, Tomás
    Coughlin, Michael W.
    Anand, Shreya
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Goobar, Ariel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kaplan, David L.
    Loveridge, Tegan T.
    Karambelkar, Viraj
    Cooke, Jeff
    Bagdasaryan, Ashot
    Bellm, Eric C.
    Cenko, S. Bradley
    Cook, David O.
    De, Kishalay
    Dekany, Richard
    Delacroix, Alexandre
    Drake, Andrew
    Duev, Dmitry A.
    Fremling, Christoffer
    Golkhou, V. Zach
    Graham, Matthew J.
    Hale, David
    Kulkarni, S. R.
    Kupfer, Thomas
    Laher, Russ R.
    Mahabal, Ashish A.
    Masci, Frank J.
    Rusholme, Ben
    Smith, Roger M.
    Tzanidakis, Anastasios
    Sistine, Angela Van
    Yao, Yuhan
    Constraining the Kilonova Rate with Zwicky Transient Facility Searches Independent of Gravitational Wave and Short Gamma-Ray Burst Triggers2020Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 904, nr 2, artikkel-id 155Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The first binary neutron star merger, GW170817, was accompanied by a radioactivity-powered optical/infrared transient called a kilonova. To date, no compelling kilonova has been found in all-sky optical surveys, independently of short gamma-ray burst and gravitational-wave triggers. In this work, we searched the first 23 months of the Zwicky Transient Facility (ZTF) data stream for candidate kilonovae in the form of rapidly evolving transients. We combined ZTF alert queries with forced point-spread-function photometry and nightly flux stacking to increase our sensitivity to faint and fast transients. Automatic queries yielded >11,200 candidates, 24 of which passed quality checks and selection criteria based on a grid of kilonova models tailored for both binary neutron star and neutron star-black hole mergers. None of the candidates in our sample was deemed a possible kilonova after thorough vetting. The sources that passed our selection criteria are dominated by Galactic cataclysmic variables. We identified two fast transients at high Galactic latitude, one of which is the confirmed afterglow of long-duration GRB.190106A, the other is a possible cosmological afterglow. Using a survey simulation code, we constrained the kilonova rate for a range of models including top-hat, linearly decaying light curves, and synthetic light curves obtained with radiative transfer simulations. For prototypical GW170817-like kilonovae, we constrain the rate to be R < 1775 Gpc(-3) yr(-1) (95% confidence). By assuming a population of kilonovae with the same geometry and composition of GW170817 observed under a uniform viewing angle distribution, we obtained a constraint on the rate of R.<.4029 Gpc(-3) yr(-1).

  • 16. Andreoni, Igor
    et al.
    Sagués Carracedo, Ana
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Schulze, Steve
    Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bulla, Mattia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kool, Erik C.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Zhang, Jielai
    A very luminous jet from the disruption of a star by a massive black hole2022Inngår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 612, nr 7940, s. 430-434Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tidal disruption events (TDEs) are bursts of electromagnetic energy that are released when supermassive black holes at the centres of galaxies violently disrupt a star that passes too close1. TDEs provide a window through which to study accretion onto supermassive black holes; in some rare cases, this accretion leads to launching of a relativistic jet2,3,4,5,6,7,8,9, but the necessary conditions are not fully understood. The best-studied jetted TDE so far is Swift J1644+57, which was discovered in γ-rays, but was too obscured by dust to be seen at optical wavelengths. Here we report the optical detection of AT2022cmc, a rapidly fading source at cosmological distance (redshift z = 1.19325) the unique light curve of which transitioned into a luminous plateau within days. Observations of a bright counterpart at other wavelengths, including X-ray, submillimetre and radio, supports the interpretation of AT2022cmc as a jetted TDE containing a synchrotron ‘afterglow’, probably launched by a supermassive black hole with spin greater than approximately 0.3. Using four years of Zwicky Transient Facility10 survey data, we calculate a rate of 0.02+0.04−0.01 Gpc−3 yr−1 for on-axis jetted TDEs on the basis of the luminous, fast-fading red component, thus providing a measurement complementary to the rates derived from X-ray and radio observations11. Correcting for the beaming angle effects, this rate confirms that approximately 1 per cent of TDEs have relativistic jets. Optical surveys can use AT2022cmc as a prototype to unveil a population of jetted TDEs.

  • 17. Arcavi, Iair
    et al.
    Howell, D. Andrew
    Kasen, Daniel
    Bildsten, Lars
    Hosseinzadeh, Griffin
    McCully, Curtis
    Wong, Zheng Chuen
    Katz, Sarah Rebekah
    Gal-Yam, Avishay
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Taddia, Francesco
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Leloudas, Giorgos
    Fremling, Christoffer
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Nugent, Peter E.
    Horesh, Assaf
    Mooley, Kunal
    Rumsey, Clare
    Cenko, S. B. Radley
    Graham, Melissa L.
    Perley, Daniel A.
    Nakar, Ehud
    Shaviv, Nir J.
    Bromberg, Omer
    Shen, Ken J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Ofek, Eran O.
    Cao, Yi
    Wang, Xiaofeng
    Huang, Fang
    Rui, Liming
    Zhang, Tianmeng
    Li, Wenxiong
    Li, Zhitong
    Zhang, Jujia
    Valenti, Stefano
    Guevel, David
    Shappee, Benjamin
    Kochanek, Christopher S.
    Holoien, Thomas W. -S.
    Filippenko, Alexei V.
    Fender, Rob
    Nyholm, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Yaron, Ofer
    Kasliwal, Mansi M. .
    Sullivan, Mark
    Lagorodnova, Nadja B.
    Walters, Richard S.
    Lunnan, Ragnhild
    Khazov, Danny
    Andreoni, Igor
    Laher, Russ R.
    Konidaris, Nick
    Wozniak, Przemek
    Bue, Brian
    Energetic eruptions leading to a peculiar hydrogen-rich explosion of a massive star2017Inngår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 551, nr 7679, s. 210-213Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Every supernova so far observed has been considered to be the terminal explosion of a star. Moreover, all supernovae with absorption lines in their spectra show those lines decreasing in velocity over time, as the ejecta expand and thin, revealing slower-moving material that was previously hidden. In addition, every supernova that exhibits the absorption lines of hydrogen has one main light-curve peak, or a plateau in luminosity, lasting approximately 100 days before declining(1). Here we report observations of iPTF14hls, an event that has spectra identical to a hydrogen-rich core-collapse supernova, but characteristics that differ extensively from those of known supernovae. The light curve has at least five peaks and remains bright for more than 600 days; the absorption lines show little to no decrease in velocity; and the radius of the line-forming region is more than an order of magnitude bigger than the radius of the photosphere derived from the continuum emission. These characteristics are consistent with a shell of several tens of solar masses ejected by the progenitor star at supernova-level energies a few hundred days before a terminal explosion. Another possible eruption was recorded at the same position in 1954. Multiple energetic pre-supernova eruptions are expected to occur in stars of 95 to 130 solar masses, which experience the pulsational pair instability(2-5). That model, however, does not account for the continued presence of hydrogen, or the energetics observed here. Another mechanism for the violent ejection of mass in massive stars may be required.

  • 18. Barbarino, C.
    et al.
    Dall'Ora, M.
    Botticella, M. T.
    Della Valle, M.
    Zampieri, L.
    Maund, J. R.
    Pumo, M. L.
    Jerkstrand, A.
    Benetti, S.
    Elias-Rosa, N.
    Fraser, M.
    Gal-Yam, A.
    Hamuy, M.
    Inserra, C.
    Knapic, C.
    LaCluyze, A. P.
    Molinaro, M.
    Ochner, P.
    Pastorello, A.
    Pignata, G.
    Reichart, D. E.
    Ries, C.
    Riffeser, A.
    Schmidt, B.
    Schmidt, M.
    Smareglia, R.
    Smartt, S. J.
    Smith, K.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Sullivan, M.
    Tomasella, L.
    Turatto, M.
    Valenti, S.
    Yaron, O.
    Young, D.
    SN 2012ec: mass of the progenitor from PESSTO follow-up of the photospheric phase2015Inngår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 448, nr 3, s. 2312-2331Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present the results of a photometric and spectroscopic monitoring campaign of SN 2012ec, which exploded in the spiral galaxy NGC 1084, during the photospheric phase. The photometric light curve exhibits a plateau with luminosity L = 0.9 x 10(42) erg s(-1) and duration similar to 90 d, which is somewhat shorter than standard Type II-P supernovae (SNe). We estimate the nickel mass M(Ni-56) = 0.040 +/- 0.015 M-circle dot from the luminosity at the beginning of the radioactive tail of the light curve. The explosion parameters of SN 2012ec were estimated from the comparison of the bolometric light curve and the observed temperature and velocity evolution of the ejecta with predictions from hydrodynamical models. We derived an envelope mass of 12.6 M-circle dot, an initial progenitor radius of 1.6 x 10(13) cm and an explosion energy of 1.2 foe. These estimates agree with an independent study of the progenitor star identified in pre-explosion images, for which an initial mass of M = 14-22 M-circle dot was determined. We have applied the same analysis to two other Type II-P SNe (SNe 2012aw and 2012A), and carried out a comparison with the properties of SN 2012ec derived in this paper. We find a reasonable agreement between the masses of the progenitors obtained from pre-explosion images and masses derived from hydrodynamical models. We estimate the distance to SN 2012ec with the standardized candle method (SCM) and compare it with other estimates based on other primary and secondary indicators. SNe 2012A, 2012aw and 2012ec all follow the standard relations for the SCM for the use of Type II-P SNe as distance indicators.

  • 19.
    Barbarino, Cristina
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Taddia, Francesco
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Fremling, C.
    Karamehmetoglu, E.
    Arcavi, I.
    Gal-Yam, A.
    Laher, R.
    Schulze, S.
    Wozniak, P.
    Yan, Lin
    Type Ic supernovae from the (intermediate) Palomar Transient Factory2021Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 651, artikkel-id A81Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Context. Type Ic supernovae represent the explosions of the most stripped massive stars, but their progenitors and explosion mechanisms remain unclear. Larger samples of observed supernovae can help characterize the population of these transients.

    Aims. We present an analysis of 44 spectroscopically normal Type Ic supernovae, with focus on the light curves. The photometric data were obtained over 7 years with the Palomar Transient Factory and its continuation, the intermediate Palomar Transient Factory. This is the first homogeneous and large sample of SNe Ic from an untargeted survey, and we aim to estimate explosion parameters for the sample.

    Methods. We present K-corrected Bgriz light curves of these SNe, obtained through photometry on template-subtracted images. We performed an analysis on the shape of the r-band light curves and confirmed the correlation between the rise parameter m 10 and the decline parameter m15. Peak r-band absolute magnitudes have an average of 17:71 +/- 0:85 mag. To derive the explosion epochs, we fit the r-band lightcurves to a template derived from a well-sampled light curve. We computed the bolometric light curves using r and g band data, g r colors and bolometric corrections. Bolometric light curves and Fe ii 5169 velocities at peak were used to fit to the Arnett semianalytic model in order to estimate the ejecta mass Mej, the explosion energy EK and the mass of radioactive nickel M(56Ni) for each SN.

    Results. Including 41 SNe, we find average values of hMej i = 4 :50 +/- 0 :79 M fi, hEK i = 1 :79 +/- 0 :29 X 1051 erg, and h M56Ni i = 0:19 X 0:03 M fi. The explosion-parameter distributions are comparable to those available in the literature, but our large sample also includes some transients with narrow and very broad light curves leading to more extreme ejecta masses values.

  • 20. Becker, A
    et al.
    Andra, 32
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Andra, 5
    Exploring the Outer Solar System with the ESSENCE Supernova Survey2008Inngår i: The Astrophysical Journal, Vol. 682, nr 1, s. L53-L56Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report the discovery and orbital determination of 14 trans-Neptunian objects (TNOs) from the ESSENCE Supernova Survey difference imaging data set. Two additional objects discovered in a similar search of the SDSS-II Supernova Survey database were recovered in this effort. ESSENCE repeatedly observed fields far from the solar system ecliptic (-21° < β < -5°), reaching limiting magnitudes per observation of I~23.1 and R~23.7. We examine several of the newly detected objects in detail, including 2003 UC414, which orbits entirely between Uranus and Neptune and lies very close to a dynamical region that would make it stable for the lifetime of the solar system. 2003 SS422 and 2007 TA418 have high eccentricities and large perihelia, making them candidate members of an outer class of TNOs. We also report a new member of the ``extended'' or ``detached'' scattered disk, 2004 VN112, and verify the stability of its orbit using numerical simulations. This object would have been visible to ESSENCE for only ~2% of its orbit, suggesting a vast number of similar objects across the sky. We emphasize that off-ecliptic surveys are optimal for uncovering the diversity of such objects, which in turn will constrain the history of gravitational influences that shaped our early solar system.

  • 21. Bellm, Eric C.
    et al.
    Kulkarni, Shrinivas R.
    Graham, Matthew J.
    Dekany, Richard
    Smith, Roger M.
    Riddle, Reed
    Masci, Frank J.
    Helou, George
    Prince, Thomas A.
    Adams, Scott M.
    Barbarino, Cristina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Barlow, Tom
    Bauer, James
    Beck, Ron
    Belicki, Justin
    Biswas, Rahul
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Blagorodnova, Nadejda
    Bodewits, Dennis
    Bolin, Bryce
    Brinnel, Valery
    Brooke, Tim
    Bue, Brian
    Bulla, Mattia
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Burruss, Rick
    Cenko, S. Bradley
    Chang, Chan-Kao
    Connolly, Andrew
    Coughlin, Michael
    Cromer, John
    Cunningham, Virginia
    De, Kishalay
    Delacroix, Alex
    Desai, Vandana
    Duev, Dmitry A.
    Eadie, Gwendolyn
    Farnham, Tony L.
    Feeney, Michael
    Feindt, Ulrich
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Flynn, David
    Franckowiak, Anna
    Frederick, S.
    Fremling, C.
    Gal-Yam, Avishay
    Gezari, Suvi
    Giomi, Matteo
    Goldstein, Daniel A.
    Golkhou, V. Zach
    Goobar, Ariel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Groom, Steven
    Hacopians, Eugean
    Hale, David
    Henning, John
    Ho, Anna Y. Q.
    Hover, David
    Howell, Justin
    Hung, Tiara
    Huppenkothen, Daniela
    Imel, David
    Ip, Wing-Huen
    Ivezic, Zeljko
    Jackson, Edward
    Jones, Lynne
    Juric, Mario
    Kasliwal, Mansi M.
    Kaspi, S.
    Kaye, Stephen
    Kelley, Michael S. P.
    Kowalski, Marek
    Kramer, Emily
    Kupfer, Thomas
    Landry, Walter
    Laher, Russ R.
    Lee, Chien-De
    Lin, Hsing Wen
    Lin, Zhong-Yi
    Lunnan, Ragnhild
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Giomi, Matteo
    Mahabal, Ashish
    Mao, Peter
    Miller, Adam A.
    Monkewitz, Serge
    Murphy, Patrick
    Ngeow, Chow-Choong
    Nordin, Jakob
    Nugent, Peter
    Ofek, Eran
    Patterson, Maria T.
    Penprase, Bryan
    Porter, Michael
    Rauch, Ludwig
    Rebbapragada, Umaa
    Reiley, Dan
    Rigault, Mickael
    Rodriguez, Hector
    van Roestel, Jan
    Rusholme, Ben
    van Santen, Jakob
    Schulze, S.
    Shupe, David L.
    Singer, Leo P.
    Soumagnac, Maayane T.
    Stein, Robert
    Surace, Jason
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Szkody, Paula
    Taddia, Francesco
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Terek, Scott
    Van Sistine, Angela
    van Velzen, Sjoert
    Vestrand, W. Thomas
    Walters, Richard
    Ward, Charlotte
    Ye, Quan-Zhi
    Yu, Po-Chieh
    Yan, Lin
    Zolkower, Jeffry
    The Zwicky Transient Facility: System Overview, Performance, and First Results2019Inngår i: Publications of the Astronomical Society of the Pacific, ISSN 0004-6280, E-ISSN 1538-3873, Vol. 131, nr 995, artikkel-id 018002Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Zwicky Transient Facility (ZTF) is a new optical time-domain survey that uses the Palomar 48 inch Schmidt telescope. A custom-built wide-field camera provides a 47 deg(2) field of view and 8 s readout time, yielding more than an order of magnitude improvement in survey speed relative to its predecessor survey, the Palomar Transient Factory. We describe the design and implementation of the camera and observing system. The ZTF data system at the Infrared Processing and Analysis Center provides near-real-time reduction to identify moving and varying objects. We outline the analysis pipelines, data products, and associated archive. Finally, we present on-sky performance analysis and first scientific results from commissioning and the early survey. ZTF's public alert stream will serve as a useful precursor for that of the Large Synoptic Survey Telescope.

  • 22. Bellm, Eric C.
    et al.
    Wang, Yuankun
    van Roestel, Jan
    Phillipson, Rebecca A.
    Coughlin, Michael W.
    Tomsick, John A.
    Groom, Steven L.
    Healy, Brian
    Purdum, Josiah
    Rusholme, Ben
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bealo, Peter
    Lora, Stefano
    Muyllaert, Eddy
    Peretto, Ivo
    Schwendeman, Erik J.
    An Optically Discovered Outburst from XTE J1859+2262023Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 956, nr 1, artikkel-id 21Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Using the Zwicky Transient Facility, in 2021 February we identified the first known outburst of the black hole X-ray transient XTE J1859+226 since its discovery in 1999. The outburst was visible at X-ray, UV, and optical wavelengths for less than 20 days, substantially shorter than its full outburst of 320 days in 1999, and the observed peak luminosity was 2 orders of magnitude lower. Its peak bolometric luminosity was only 2 × 1035 erg s−1, implying an Eddington fraction of about 3 × 10−4. The source remained in the hard spectral state throughout the outburst. From optical spectroscopy measurements we estimate an outer disk radius of 1011 cm. The low observed X-ray luminosity is not sufficient to irradiate the entire disk, but we observe a surprising exponential decline in the X-ray light curve. These observations highlight the potential of optical and infrared synoptic surveys to discover low-luminosity activity from X-ray transients.

  • 23. Benetti, S.
    et al.
    Nicholl, M.
    Cappellaro, E.
    Pastorello, A.
    Smartt, S. J.
    Elias-Rosa, N.
    Drake, A. J.
    Tomasella, L.
    Turatto, M.
    Harutyunyan, A.
    Taubenberger, S.
    Hachinger, S.
    Morales-Garoffolo, A.
    Chen, T. -W
    Djorgovski, S. G.
    Fraser, M.
    Gal-Yam, A.
    Inserra, C.
    Mazzali, P.
    Pumo, M. L.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Valenti, S.
    Young, D. R.
    Dennefeld, M.
    Le Guillou, L.
    Fleury, M.
    Leget, P. -F
    The supernova CSS121015:004244+132827: a clue for understanding superluminous supernovae2014Inngår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 441, nr 1, s. 289-303Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present optical photometry and spectra of the superluminous Type II/IIn supernova (SN) CSS121015: 004244+132827 (z = 0.2868) spanning epochs from -30 d (rest frame) to more than 200 d after maximum. CSS121015 is one of the more luminous SNe ever found and one of the best observed. The photometric evolution is characterized by a relatively fast rise to maximum (similar to 40 d in the SN rest frame), and by a linear post-maximum decline. The light curve shows no sign of a break to an exponential tail. A broad Ha is first detected at similar to+40 d (rest frame). Narrow, barely resolved Balmer and [O III] 5007 angstrom lines, with decreasing strength, are visible along the entire spectral evolution. The spectra are very similar to other superluminous supernovae (SLSNe) with hydrogen in their spectrum, and also to SN 2005gj, sometimes considered Type Ia interacting with H-rich circumstellar medium. The spectra are also similar to a subsample of H-deficient SLSNe. We propose that the properties of CSS121015 are consistent with the interaction of the ejecta with a massive, extended, opaque shell, lost by the progenitor decades before the final explosion, although a magnetar-powered model cannot be excluded. Based on the similarity of CSS121015 with other SLSNe (with and without H), we suggest that the shocked-shell scenario should be seriously considered as a plausible model for both types of SLSN.

  • 24. Bersten, Melina C.
    et al.
    Benvenuto, Omar G.
    Nomoto, Ken'ichi
    Ergon, Mattias
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Folatelli, Gaston
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Benetti, Stefano
    Botticella, Maria Teresa
    Fraser, Morgan
    Kotak, Rubina
    Maeda, Keiichi
    Ochner, Paolo
    Tomasella, Lina
    THE TYPE IIb SUPERNOVA 2011dh FROM A SUPERGIANT PROGENITOR2012Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 757, nr 1, artikkel-id 31Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A set of hydrodynamical models based on stellar evolutionary progenitors is used to study the nature of SN 2011dh. Our modeling suggests that a large progenitor star-with R similar to 200 R-circle dot-is needed to reproduce the early light curve (LC) of SN 2011dh. This is consistent with the suggestion that the yellow super-giant star detected at the location of the supernova (SN) in deep pre-explosion images is the progenitor star. From the main peak of the bolometric LC and expansion velocities, we constrain the mass of the ejecta to be approximate to 2 M-circle dot, the explosion energy to be E = (6-10) x 10(50) erg, and the Ni-56 mass to be approximately 0.06 M-circle dot. The progenitor star was composed of a helium core of 3-4 M-circle dot and a thin hydrogen-rich envelope of approximate to 0.1M(circle dot) with a main-sequence mass estimated to be in the range of 12-15 M-circle dot. Our models rule out progenitors with helium-core masses larger than 8 M-circle dot, which correspond to M-ZAMS greater than or similar to 25M(circle dot). This suggests that a single star evolutionary scenario for SN 2011dh is unlikely.

  • 25. Betoule, M.
    et al.
    Kessler, R.
    Guy, J.
    Mosher, J.
    Hardin, D.
    Biswas, R.
    Astier, P.
    El-Hage, P.
    Konig, M.
    Kuhlmann, S.
    Marriner, J.
    Pain, R.
    Regnault, N.
    Balland, C.
    Bassett, B. A.
    Brown, P. J.
    Campbell, H.
    Carlberg, R. G.
    Cellier-Holzern, F.
    Cinabro, D.
    Conley, A.
    D'Andrea, C. B.
    DePoy, D. L.
    Doi, M.
    Ellis, R. S.
    Fabbro, S.
    Filippenko, A. V.
    Foley, R. J.
    Frieman, J. A.
    Fouchez, D.
    Galbany, L.
    Goobar, Ariel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Gupta, R. R.
    Hill, G. J.
    Hlozek, R.
    Hogan, C. J.
    Hook, I. M.
    Howell, D. A.
    Jha, S. W.
    Le Guillou, L.
    EGENLeloudas, G.
    Lidrnan, C.
    Marshall, J. L.
    Moeller, A.
    Mourao, A. M.
    Neveu, J.
    Nichol, R.
    Olmstead, M. D.
    Palanque-Delabrouille, N.
    Perlinutter, S.
    Prieto, J. L.
    Pritchet, C. J.
    Richinond, M.
    Riess, A. G.
    Ruhlmann-Kleider, V.
    Sako, M.
    Sehahmaneche, K.
    Schneider, D. P.
    Smith, M.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Sullivan, M.
    Walton, N. A.
    Wheeler, C. J.
    Improved cosmological constraints from a joint analysis of the SDSS-II and SNLS supernova samples2014Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 568, s. A22-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aims. We present cosmological constraints from a joint analysis of type la supernova (SN Ia) observations obtained by the SDSS-II and SNLS collaborations. The dataset includes several low-redshift samples (z < 0.1), all three seasons from the SDSS-11 (0.05 < z < 0.4), and three years from SNLS (0.2 < z < 1), and it totals 740 spectroscopically confirmed type la supernovae with high quality light curves. Methods. We followed the methods and assumptions of the SNLS three-year data analysis except for the following important improvements: I) the addition of the full SDSS-II spectroscopically-confirmed SN la sample in both the training of the SALT2 light-curve model and in the Hubble diagram analysis (374 SNe); 2) intercalibration of the SNLS and SDSS surveys and reduced systematic uncertainties in the photometric calibration, performed blindly with respect to the cosmology analysis; and 3) a thorough investigation of systematic errors associated with the SALT2 modeling of SN la light curves. Results. We produce recalibrated SN la light curves and associated distances for the SDSS-II and SNLS samples. The large SOSS-II sample provides an effective, independent, low -z anchor for the Hubble diagram and reduces the systematic error from calibration systematics in the low -z SN sample. For a flat ACDM cosmology, we find Omega(m), = 0.295 0.034 (stat+sys), a value consistent with the most recent cosmic microwave background (CMB) measurement from the Planck and WMAP experiments. Our result is 1.8 sigma (stat+sys) different than the previously published result of SNLS three-year data. The change is due primarily to improvements in the SNLS photometric calibration. When combined with CMB constraints, we measure a constant dark energy equation of state parameter omega = -1.018 +/- 0,057 (sral+sys) for a fiat universe. Adding baryon acoustic oscillation distance measurements gives similar constraints: omega = 59 -1.027 0.055. Our supernova measurements provide the most stringent constraints to date on the nature of dark energy.

  • 26.
    Biswas, Rahul
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Goobar, Ariel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Dhawan, Suhail
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). University of Cambridge, UK.
    Schulze, Steve
    Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Johansson, Joel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bellm, Eric C.
    Dekany, Richard
    Drake, Andrew J.
    Duev, Dmitry A.
    Fremling, Christoffer
    Graham, Matthew
    Kim, Young-Lo
    Kool, Erik C.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kulkarni, Shrinivas R.
    Mahabal, Ashish A.
    Perley, Daniel
    Rigault, Mickael
    Rusholme, Ben
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholm Univ, Oskar Klein Ctr, Dept Astron, SE-10691 Stockholm, Sweden.
    Shupe, David L.
    Smith, Matthew
    Walters, Richard S.
    Two c's in a pod: cosmology-independent measurement of the Type Ia supernova colour-luminosity relation with a sibling pair2022Inngår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 509, nr 4, s. 5340-5356Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Using Zwicky Transient Facility (ZTF) observations, we identify a pair of ‘sibling’ Type Ia supernovae (SNe Ia), i.e. hosted by the same galaxy at z = 0.0541. They exploded within 200 d from each other at a separation of 0.6arcsec0.6arcsec corresponding to a projected distance of only 0.6 kpc. Performing SALT2 light-curve fits to the gri ZTF photometry, we show that for these equally distant ‘standardizable candles’, there is a difference of 2 mag in their rest-frame B-band peaks, and the fainter supernova (SN) has a significantly red SALT2 colour c = 0.57 ± 0.04, while the stretch values x1 of the two SNe are similar, suggesting that the fainter SN is attenuated by dust in the interstellar medium of the host galaxy. We use these measurements to infer the SALT2 colour standardization parameter, β = 3.5 ± 0.3, independent of the underlying cosmology and Malmquist bias. Assuming the colour excess is entirely due to dust, the result differs by 2σ from the average Milky Way total-to-selective extinction ratio, but is in good agreement with the colour–brightness corrections empirically derived from the most recent SN Ia Hubble–Lemaitre diagram fits. Thus we suggest that SN ‘siblings’, which will increasingly be discovered in the coming years, can be used to probe the validity of the colour and light-curve shape corrections using in SN Ia cosmology while avoiding important systematic effects in their inference from global multiparameter fits to inhomogeneous data sets, and also help constrain the role of interstellar dust in SN Ia cosmology.

  • 27.
    Björnsson, Claes-Ingvar
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Sandberg, Andreas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    The location of the Crab pulsar emission region: restrictions on synchrotron emission models2010Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 516, s. A65-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recent observations of the Crab pulsar show no evidence of a spectral break in the infrared regime. It is argued that the observations are consistent with a power-law spectrum in the whole observable infrared-optical range. This is taken as the starting point for evaluating of how self-consistent incoherent synchrotron models fare in a comparison with observations. Inclusion of synchrotron self-absorption proves important as does the restriction on the observed size of the emission region imposed by the relativistic beaming thought to define the pulse profile. It is shown that the observations can be used to derive two independent constraints on the distance from the neutron star to the emission region; in addition to a direct lower limit, an indirect measure is obtained from an upper limit to the magnetic field strength. Both of these limits indicate that the emission region is located at a distance considerably greater than the light cylinder radius. The implications of this result are discussed, and it is emphasized that, for standard incoherent synchrotron models to fit inside the light cylinder, rather special physical conditions need to be invoked.

  • 28. Blagorodnova, N.
    et al.
    Kotak, R.
    Polshaw, J.
    Kasliwal, M. M.
    Cao, Y.
    Cody, A. M.
    Doran, G. B.
    Elias-Rosa, N.
    Fraser, M.
    Fremling, Christoffer
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Gonzalez-Fernandez, C.
    Harmanen, J.
    Jencson, J.
    Kankare, E.
    Kudritzki, R. -P.
    Kulkarni, S. R.
    Magnier, E.
    Manulis, I.
    Masci, F. J.
    Mattila, S.
    Nugent, P.
    Ochner, P.
    Pastorello, A.
    Reynolds, T.
    Smith, K.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Taddia, Francesco
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Terreran, G.
    Tomasella, L.
    Turatto, M.
    Vreeswijk, P. M.
    Wozniak, P.
    Zaggia, S.
    COMMON ENVELOPE EJECTION FOR A LUMINOUS RED NOVA IN M1012017Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 834, nr 2, artikkel-id 107Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present the results of optical, near-infrared, and mid-infrared observations of M101 OT2015-1 (PSN J14021678+ 5426205), a luminous red transient in the Pinwheel galaxy (M101), spanning a total of 16 years. The light curve showed two distinct peaks with absolute magnitudes M-r <= -12.4 and M-r similar or equal to -12, on 2014 November 11 and 2015 February 17, respectively. The spectral energy distributions during the second maximum show a cool outburst temperature of approximate to 3700 K and low expansion velocities (approximate to -300 km s(-1)) for the H I, Ca II, Ba II, and K I lines. From archival data spanning 15-8 years before the outburst, we find a single source consistent with the optically discovered transient, which we attribute to being the progenitor; it has properties consistent with being an F-type yellow supergiant with L similar to 8.7 x 10(4) L-circle dot, T-eff approximate to 7000. K, and an estimated mass of M1= 18 +/- 1 M-circle dot. This star has likely just finished the H-burning phase in the core, started expanding, and is now crossing the Hertzsprung gap. Based on the combination of observed properties, we argue that the progenitor is a binary system, with the more evolved system overfilling the Roche lobe. Comparison with binary evolution models suggests that the outburst was an extremely rare phenomenon, likely associated with the ejection of the common envelope of a massive star. The initial mass of the primary fills the gap between the merger candidates V838 Mon (5-10 M-circle dot) and NGC. 4490-OT. (30M(circle dot)).

  • 29. Blondin, S
    et al.
    Andra, 3
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Andra, 27
    Time Dilation in Type Ia Supernova Spectra at High Redshift2008Inngår i: The Astrophysical Journal, Vol. 682, nr 2, s. 724-736Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present multiepoch spectra of 13 high-redshift Type Ia supernovae (SNe Ia) drawn from the literature, the ESSENCE and SNLS projects, and our own separate dedicated program on the ESO Very Large Telescope. We use the Supernova Identification (SNID) code of Blondin and Tonry to determine the spectral ages in the supernova rest frame. Comparison with the observed elapsed time yields an apparent aging rate consistent with the 1/(1+z) factor (where z is the redshift) expected in a homogeneous, isotropic, expanding universe. These measurements thus confirm the expansion hypothesis, while unambiguously excluding models that predict no time dilation, such as Zwicky's ``tired light'' hypothesis. We also test for power-law dependencies of the aging rate on redshift. The best-fit exponent for these models is consistent with the expected 1/(1+z) factor.

  • 30. Boles, T.
    et al.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Stritzinger, M.
    Hammer Holm, A.
    Jul Jensen, J.
    Paaske Drachmann, A.
    Juhl Hobert, M.
    Fynbo, J.
    Fraser, M.
    Wright, D.
    Kotak, R.
    Arcavi, I.
    Supernova 2012eg in NGC 1213 = Psn J03091697+38382072012Rapport (Annet vitenskapelig)
    Abstract [en]

    CBET 3207 available at Central Bureau for Astronomical Telegrams.

  • 31. Bolin, Bryce T.
    et al.
    Lisse, Carey M.
    Kasliwal, Mansi M.
    Quimby, Robert
    Tan, Hanjie
    Copperwheat, Chris M.
    Lin, Zhong-Yi
    Morbidelli, Alessandro
    Abe, Lyu
    Bendjoya, Philippe
    Burdge, Kevin B.
    Coughlin, Michael
    Fremling, Christoffer
    Itoh, Ryosuke
    Koss, Michael
    Masci, Frank J.
    Maeno, Syota
    Mamajek, Eric E.
    Marocco, Federico
    Murata, Katsuhiro
    Rivet, Jean-Pierre
    Sitko, Michael L.
    Stern, Daniel
    Vernet, David
    Walters, Richard
    Yan, Lin
    Andreoni, Igor
    Bhalerao, Varun
    Bodewits, Dennis
    De, Kishalay
    Deshmukh, Kunal P.
    Bellm, Eric C.
    Blagorodnova, Nadejda
    Buzasi, Derek
    Cenko, S. Bradley
    Chang, Chan-Kao
    Chojnowski, Drew
    Dekany, Richard
    Duev, Dmitry A.
    Graham, Matthew
    Juric, Mario
    Kulkarni, Shrinivas R.
    Kupfer, Thomas
    Mahabal, Ashish
    Neill, James D.
    Ngeow, Chow-Choong
    Penprase, Bryan
    Riddle, Reed
    Rodriguez, Hector
    Smith, Roger M.
    Rosnet, Philippe
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Soumagnac, Maayane T.
    Characterization of the Nucleus, Morphology, and Activity of Interstellar Comet 2I/Borisov by Optical and Near-infrared GROWTH, Apache Point, IRTF, ZTF, and Keck Observations2020Inngår i: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 160, nr 1, artikkel-id 26Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present visible and near-infrared (NIR) photometric and spectroscopic observations of interstellar object (ISO) 2I/Borisov taken from 2019 September 10 to 2019 December 20 using the GROWTH, the Apache Point Observatory Astrophysical Research Consortium 3.5 m, and the NASA Infrared Telescope Facility 3.0 m combined with pre- and postdiscovery observations of 2I obtained by the Zwicky Transient Facility from 2019 March 17 to 2019 May 5. Comparison with imaging of distant solar system comets shows an object very similar to mildly active solar system comets with an outgassing rate of similar to 10(27)mol s(-1). The photometry, taken in filters spanning the visible and NIR range, shows a gradual brightening trend of similar to 0.03 mag day(-1)since 2019 September 10 UTC for a reddish object becoming neutral in the NIR. The light curve from recent and prediscovery data reveals a brightness trend suggesting the recent onset of significant H2O sublimation with the comet being active with super volatiles such as CO at heliocentric distances >6 au consistent with its extended morphology. Using the advanced capability to significantly reduce the scattered light from the coma enabled by high-resolution NIR images from Keck adaptive optics taken on 2019 October 4, we estimate a diameter for 2I's nucleus of less than or similar to 1.4 km. We use the size estimates of 1I/'Oumuamua and 2I/Borisov to roughly estimate the slope of the ISO size distribution, resulting in a slope of similar to 3.4 1.2, similar to solar system comets and bodies produced from collisional equilibrium.

  • 32. Brennan, S. J.
    et al.
    Fraser, M.
    Johansson, Joel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Pastorello, A.
    Kotak, R.
    Stevance, H. F.
    Chen, Ting-Wan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Max-Planck-Institut für Extraterrestrische Physik, Germany.
    Eldridge, J. J.
    Bose, S.
    Brown, P. J.
    Callis, E.
    Cartier, R.
    Dennefeld, M.
    Dong, Subo
    Duffy, P.
    Elias-Rosa, N.
    Hosseinzadeh, G.
    Hsiao, E.
    Kuncarayakti, H.
    Martin-Carrillo, A.
    Monard, B.
    Pignata, G.
    Sand, D.
    Shappee, B. J.
    Smartt, S. J.
    Tucker, B. E.
    Wyrzykowski, L.
    Abbot, H.
    Benetti, S.
    Bento, J.
    Blondin, S.
    Chen, Ping
    Delgado, A.
    Galbany, L.
    Gromadzki, M.
    Gutiérrez, C. P.
    Hanlon, L.
    Harrison, D. L.
    Hiramatsu, D.
    Hodgkin, S. T.
    Holoien, T. W.-S.
    Howell, D. A.
    Inserra, C.
    Kankare, E.
    Kozłowski, S.
    Müller-Bravo, T. E.
    Maguire, K.
    McCully, C.
    Meintjes, P.
    Morrell, N.
    Nicholl, M.
    O'Neill, D.
    Pietrukowicz, P.
    Poleski, R.
    Prieto, J. L.
    Rau, A.
    Reichart, D. E.
    Schweyer, Tassilo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Shahbandeh, M.
    Skowron, J.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Soszyński, I.
    Stritzinger, M. D.
    Szymański, M.
    Tartaglia, L.
    Udalski, A.
    Ulaczyk, K.
    Young, D. R.
    van Leeuwen, M.
    van Soelen, B.
    Progenitor, environment, and modelling of the interacting transient AT 2016jbu (Gaia16cfr)2022Inngår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 513, nr 4, s. 5666-5685Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present the bolometric light curve, identification and analysis of the progenitor candidate, and preliminary modelling of AT 2016jbu (Gaia16cfr). We find a progenitor consistent with a ∼ 22–25 M⊙ yellow hypergiant surrounded by a dusty circumstellar shell, in agreement with what has been previously reported. We see evidence for significant photometric variability in the progenitor, as well as strong Hα emission consistent with pre-existing circumstellar material. The age of the environment, as well as the resolved stellar population surrounding AT 2016jbu, supports a progenitor age of >10 Myr, consistent with a progenitor mass of ∼22 M⊙. A joint analysis of the velocity evolution of AT 2016jbu and the photospheric radius inferred from the bolometric light curve shows the transient is consistent with two successive outbursts/explosions. The first outburst ejected material with velocity ∼650 km s−1, while the second, more energetic event ejected material at ∼4500 km s−1. Whether the latter is the core collapse of the progenitor remains uncertain. We place a limit on the ejected 56Ni mass of <0.016 M⊙. Using the Binary Population And Spectral Synthesis (BPASS) code, we explore a wide range of possible progenitor systems and find that the majority of these are in binaries, some of which are undergoing mass transfer or common-envelope evolution immediately prior to explosion. Finally, we use the SuperNova Explosion Code (SNEC) to demonstrate that the low-energy explosions within some of these binary systems, together with sufficient circumstellar material, can reproduce the overall morphology of the light curve of AT 2016jbu.

  • 33. Brennan, S. J.
    et al.
    Fraser, M.
    Pearson Johansson, Joel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Pastorello, A.
    Kotak, R.
    Stevance, H. F.
    Chen, Ting-Wan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Max-Planck-Institut für Extraterrestrische Physik, Germany.
    Eldridge, J. J.
    Bose, S.
    Brown, P. J.
    Callis, E.
    Cartier, R.
    Dennefeld, M.
    Dong, Subo
    Duffy, P.
    Elias-Rosa, N.
    Hosseinzadeh, G.
    Hsiao, E.
    Kuncarayakti, H.
    Martin-Carrillo, A.
    Monard, B.
    Nyholm, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Pignata, G.
    Sand, D.
    Shappee, B. J.
    Smartt, S. J.
    Tucker, B. E.
    Wyrzykowski, L.
    Abbot, H.
    Benetti, S.
    Bento, J.
    Blondin, S.
    Chen, Ping
    Delgado, A.
    Galbany, L.
    Gromadzki, M.
    Gutiérrez, C. P.
    Hanlon, L.
    Harrison, D. L.
    Hiramatsu, D.
    Hodgkin, S. T.
    Holoien, T. W.-S.
    Howell, D. A.
    Inserra, C.
    Kankare, E.
    Kozłowski, S.
    Müller-Bravo, T. E.
    Maguire, K.
    McCully, C.
    Meintjes, P.
    Morrell, N.
    Nicholl, M.
    O'Neill, D.
    Pietrukowicz, P.
    Poleski, R.
    Prieto, J. L.
    Rau, A.
    Reichart, D. E.
    Schweyer, Tassilo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Max-Planck-Institut für Extraterrestrische Physik, Germany.
    Shahbandeh, M.
    Skowron, J.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Soszyński, I.
    Stritzinger, M. D.
    Szymański, M.
    Tartaglia, L.
    Udalski, A.
    Ulaczyk, K.
    Young, D. R.
    van Leeuwen, M.
    van Soelen, B.
    Photometric and spectroscopic evolution of the interacting transient AT 2016jbu(Gaia16cfr)2022Inngår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 513, nr 4, s. 5642-5665Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present the results from a high-cadence, multiwavelength observation campaign of AT 2016jbu (aka Gaia16cfr), an interacting transient. This data set complements the current literature by adding higher cadence as well as extended coverage of the light-curve evolution and late-time spectroscopic evolution. Photometric coverage reveals that AT 2016jbu underwent significant photometric variability followed by two luminous events, the latter of which reached an absolute magnitude of MV ∼ −18.5 mag. This is similar to the transient SN 2009ip whose nature is still debated. Spectra are dominated by narrow emission lines and show a blue continuum during the peak of the second event. AT 2016jbu shows signatures of a complex, non-homogeneous circumstellar material (CSM). We see slowly evolving asymmetric hydrogen line profiles, with velocities of 500 km s−1 seen in narrow emission features from a slow-moving CSM, and up to 10 000 km s−1 seen in broad absorption from some high-velocity material. Late-time spectra (∼+1 yr) show a lack of forbidden emission lines expected from a core-collapse supernova and are dominated by strong emission from H, He I, and Ca II. Strong asymmetric emission features, a bumpy light curve, and continually evolving spectra suggest an inhibit nebular phase. We compare the evolution of H α among SN 2009ip-like transients and find possible evidence for orientation angle effects. The light-curve evolution of AT 2016jbu suggests similar, but not identical, circumstellar environments to other SN 2009ip-like transients.

  • 34.
    Brennan, Seán J.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Irani, I.
    Schulze, Steve
    Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Weizmann Institute of Science, Israel.
    Chen, P.
    Das, K. K.
    De, K.
    Fransson, Claes
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Gal-Yam, A.
    Gkini, Anamaria
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hinds, K. R.
    Lunnan, Ragnhild
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Perley, D.
    Qin, Y. J.
    Stein, R.
    Wise, J.
    Yan, L.
    Zimmerman, E. A.
    Anand, S.
    Bruch, R. J.
    Dekany, R.
    Drake, A. J.
    Fremling, C.
    Healy, B.
    Karambelkar, V.
    Kasliwal, M. M.
    Kong, M.
    Kulkarni, S. R.
    Masci, F. J.
    Post, R. S.
    Purdum, J.
    Rich, R. Michael
    Wold, A.
    Spectroscopic observations of progenitor activity 100 days before a Type Ibn supernova2024Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 684, artikkel-id L18Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Obtaining spectroscopic observations of the progenitors of core-collapse supernovae is often unfeasible, due to an inherent lack of knowledge as to what stars experience supernovae and when they will explode. In this Letter we present photometric and spectroscopic observations of the progenitor activity of SN 2023fyq before the He-rich progenitor explodes as a Type Ibn supernova. The progenitor of SN 2023fyq shows an exponential rise in flux prior to core collapse. Complex He I emission line features are observed in the progenitor spectra, with a P Cygni-like profile, as well as an evolving broad base with velocities of the order of 10 000 km s−1. The luminosity and evolution of SN 2023fyq is consistent with a Type Ibn, reaching a peak r-band magnitude of −18.8 mag, although there is some uncertainty regarding the distance to the host, NGC 4388, which is located in the Virgo cluster. We present additional evidence of asymmetric He-rich material being present both prior to and after the explosion of SN 2023fyq, which suggests that this material survived the ejecta interaction. Broad [O I], C I, and the Ca II triplet lines are observed at late phases, confirming that SN 2023fyq was a genuine supernova, rather than a non-terminal interacting transient. SN 2023fyq provides insight into the final moments of a massive star’s life, demonstrating that the progenitor is likely highly unstable before core collapse.

  • 35. Brimacombe, J.
    et al.
    Bros, X.
    Mikuz, B.
    Skielboe, A.
    Paarup, T.
    Knudsen, S.
    Stockman, M.
    Geier, S.
    Fynbo, J.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Stritzinger, M.
    Stockholms universitet.
    Skvarc, J.
    Supernova 2011fc = Psn J23013638+32200692011Inngår i: Central Bureau Electronic Telegrams, Vol. 2788, s. 2-Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    CBET 2788 available at Central Bureau for Astronomical Telegrams.

  • 36. Bruch, Rachel J.
    et al.
    Gal-Yam, Avishay
    Schulze, Steve
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Weizmann Institute of Science, Israel.
    Yaron, Ofer
    Yang, Yi
    Soumagnac, Maayane
    Rigault, Mickael
    Strotjohann, Nora L.
    Ofek, Eran
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Masci, Frank J.
    Barbarino, Cristina
    Ho, Anna Y. Q.
    Fremling, Christoffer
    Perley, Daniel
    Nordin, Jakob
    Cenko, S. Bradley
    Adams, S.
    Adreoni, Igor
    Bellm, Eric C.
    Blagorodnova, Nadia
    Bulla, Mattia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Burdge, Kevin
    De, Kishalay
    Dhawan, Suhail
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Drake, Andrew J.
    Duev, Dmitry A.
    Dugas, Alison
    Graham, Matthew
    Graham, Melissa L.
    Irani, Ido
    Jencson, Jacob
    Karamehmetoglu, Emir
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Aarhus University, Denmark.
    Kasliwal, Mansi
    Kim, Young-Lo
    Kulkarni, Shrinivas
    Kupfer, Thomas
    Liang, Jingyi
    Mahabal, Ashish
    Miller, A. A.
    Prince, Thomas A.
    Riddle, Reed
    Sharma, Y.
    Smith, Roger
    Taddia, Francesco
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Aarhus University, Denmark.
    Taggart, Kirsty
    Walters, Richard
    Yan, Lin
    A Large Fraction of Hydrogen-rich Supernova Progenitors Experience Elevated Mass Loss Shortly Prior to Explosion2021Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 912, nr 1, artikkel-id 46Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Spectroscopic detection of narrow emission lines traces the presence of circumstellar mass distributions around massive stars exploding as core-collapse supernovae. Transient emission lines disappearing shortly after the supernova explosion suggest that the material spatial extent is compact and implies an increased mass loss shortly prior to explosion. Here, we present a systematic survey for such transient emission lines (Flash Spectroscopy) among Type II supernovae detected in the first year of the Zwicky Transient Facility survey. We find that at least six out of ten events for which a spectrum was obtained within two days of the estimated explosion time show evidence for such transient flash lines. Our measured flash event fraction (>30% at 95% confidence level) indicates that elevated mass loss is a common process occurring in massive stars that are about to explode as supernovae.

  • 37. Bruch, Rachel J.
    et al.
    Gal-Yam, Avishay
    Yaron, Ofer
    Chen, Ping
    Strotjohann, Nora L.
    Irani, Ido
    Zimmerman, Erez
    Schulze, Steve
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Weizmann Institute of Science, Israel.
    Yang, Yi
    Kim, Young-Lo
    Bulla, Mattia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Rigault, Mickael
    Ofek, Eran
    Soumagnac, Maayane
    Masci, Frank J.
    Fremling, Christoffer
    Perley, Daniel
    Nordin, Jakob
    Cenko, S. Bradley
    Ho, Anna Y. Q.
    Adams, S.
    Adreoni, Igor
    Bellm, Eric C.
    Blagorodnova, Nadia
    Burdge, Kevin
    De, Kishalay
    Dekany, Richard G.
    Dhawan, Suhail
    Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Drake, Andrew J.
    Duev, Dmitry A.
    Graham, Matthew
    Graham, Melissa L.
    Jencson, Jacob
    Karamehmetoglu, Emir
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Aarhus University, Denmark.
    Kasliwal, Mansi M.
    Kulkarni, Shrinivas
    Miller, A. A.
    Neill, James D.
    Prince, Thomas A.
    Riddle, Reed
    Rusholme, Benjamin
    Sharma, Y.
    Smith, Roger
    Sravan, Niharika
    Taggart, Kirsty
    Walters, Richard
    Yan, Lin
    The Prevalence and Influence of Circumstellar Material around Hydrogen-rich Supernova Progenitors2023Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 952, nr 2, artikkel-id 119Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Narrow transient emission lines (flash-ionization features) in early supernova (SN) spectra trace the presence of circumstellar material (CSM) around the massive progenitor stars of core-collapse SNe. The lines disappear within days after the SN explosion, suggesting that this material is spatially confined, and originates from enhanced mass loss shortly (months to a few years) prior to the explosion. We performed a systematic survey of H-rich (Type II) SNe discovered within less than 2 days from the explosion during the first phase of the Zwicky Transient Facility survey (2018–2020), finding 30 events for which a first spectrum was obtained within <2 days from the explosion. The measured fraction of events showing flash-ionization features (>36% at the 95% confidence level) confirms that elevated mass loss in massive stars prior to SN explosion is common. We find that SNe II showing flash-ionization features are not significantly brighter, nor bluer, nor more slowly rising than those without. This implies that CSM interaction does not contribute significantly to their early continuum emission, and that the CSM is likely optically thin. We measured the persistence duration of flash-ionization emission and find that most SNe show flash features for ≈5 days. Rarer events, with persistence timescales >10 days, are brighter and rise longer, suggesting these may be intermediate between regular SNe II and strongly interacting SNe IIn.

  • 38. Bufano, F.
    et al.
    Benetti, S.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Pian, E.
    Cupani, G.
    Studying the SN-GRB connection with X-shooter: The GRB 100316D / SN 2010bh case2011Inngår i: Astronomical Notes - Astronomische Nachrichten, ISSN 0004-6337, E-ISSN 1521-3994, Vol. 332, nr 3, s. 262-265Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During the last ten years, observations of long-duration gamma-ray bursts brought to the conclusion that at least a fraction of them is associated with bright supernovae of type Ib/c. In this talk, after a short review on the previously observed GRB-SN connection cases, we present the recent case of GRB 100316/SN 2010bh. In particular, during the observational campaign of SN 2010bh, a pivotal role was played by VLT/X-shooter, sampling with unique high quality data the spectral energy distribution of the early evolution phases from the UV to the K band. Based on observations collected at the European Southern Observatory, ESO, the VLT/Kueyen telescope, Paranal, Chile, proposal codes 084.D-0265 and 085.D-0701, P.I. S.Benetti and 084.A-0260 and 085.A-0009, P.I. J.Fynbo.

  • 39. Bufano, Filomena
    et al.
    Pian, Elena
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Benetti, Stefano
    Pignata, Giuliano
    Valenti, Stefano
    Covino, Stefano
    D'Avanzo, Paolo
    Malesani, Daniele
    Cappellaro, Enrico
    Della Valle, Massimo
    Fynbo, Johan
    Hjorth, Jens
    Mazzali, Paolo A.
    Reichart, Daniel E.
    Starling, Rhaana L. C.
    Turatto, Massimo
    Vergani, Susanna D.
    Wiersema, Klass
    Amati, Lorenzo
    Bersier, David
    Campana, Sergio
    Cano, Zach
    Castro-Tirado, Alberto J.
    Chincarini, Guido
    D'Elia, Valerio
    Postigo, Antonio de Ugarte
    Deng, Jinsong
    Ferrero, Patrizia
    Filippenko, Alexei V.
    Goldoni, Paolo
    Gorosabel, Javier
    Greiner, Jochen
    Hammer, Francois
    Jakobsson, Pall
    Kaper, Lex
    Kawabata, Koji S.
    Klose, Sylvio
    Levan, Andrew J.
    Maeda, Keiichi
    Masetti, Nicola
    Milvang-Jensen, Bo
    Mirabel, Felix I.
    Moller, Palle
    Nomoto, Ken'ichi
    Palazzi, Eliana
    Piranomonte, Silvia
    Salvaterra, Ruben
    Stratta, Giulia
    Tagliaferri, Gianpiero
    Tanaka, Masaomi
    Tanvir, Nial R.
    Wijers, Ralph A. M. J.
    THE HIGHLY ENERGETIC EXPANSION OF SN 2010bh ASSOCIATED WITH GRB 100316D2012Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 753, nr 1, s. 67-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present the spectroscopic and photometric evolution of the nearby (z = 0.059) spectroscopically confirmed Type Ic supernova, SN 2010bh, associated with the soft, long-duration gamma-ray burst (X-ray flash) GRB 100316D. Intensive follow-up observations of SN 2010bh were performed at the ESO Very Large Telescope (VLT) using the X-shooter and FORS2 instruments. Thanks to the detailed temporal coverage and the extended wavelength range (3000-24800 angstrom), we obtained an unprecedentedly rich spectral sequence among the hypernovae, making SN 2010bh one of the best studied representatives of this SN class. We find that SN 2010bh has a more rapid rise to maximum brightness (8.0 +/- 1.0 rest-frame days) and a fainter absolute peak luminosity (L-bol approximate to 3 x 10(42) erg s(-1)) than previously observed SN events associated with GRBs. Our estimate of the ejected Ni-56 mass is 0.12 +/- 0.02 M-circle dot. From the broad spectral features, we measure expansion velocities up to 47,000 km s(-1), higher than those of SNe 1998bw (GRB 980425) and 2006aj (GRB 060218). Helium absorption lines He I lambda 5876 and He I 1.083 mu m, blueshifted by similar to 20,000-30,000 km s(-1) and similar to 28,000-38,000 km s(-1), respectively, may be present in the optical spectra. However, the lack of coverage of the He I 2.058 mu m line prevents us from confirming such identifications. The nebular spectrum, taken at similar to 186 days after the explosion, shows a broad but faint [O I] emission at 6340 angstrom. The light curve shape and photospheric expansion velocities of SN 2010bh suggest that we witnessed a highly energetic explosion with a small ejected mass (E-k approximate to 10(52) erg and M-ej approximate to 3 M-circle dot). The observed properties of SN 2010bh further extend the heterogeneity of the class of GRB SNe.

  • 40.
    Bulla, Mattia
    et al.
    Stockholms universitet, Nordiska institutet för teoretisk fysik (Nordita). Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Miller, Adam A.
    Yao, Yuhan
    Dessart, Luc
    Dhawan, Suhail
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Papadogiannakis, Semeli
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Biswas, Rahul
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Goobar, Ariel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kulkarni, S. R.
    Nordin, Jakob
    Nugent, Peter
    Polin, Abigail
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bellm, Eric C.
    Coughlin, Michael W.
    Dekany, Richard
    Golkhou, V. Zach
    Graham, Matthew J.
    Kasliwal, Mansi M.
    Kupfer, Thomas
    Laher, Russ R.
    Masci, Frank J.
    Porter, Michael
    Rusholme, Ben
    Shupe, David L.
    ZTF Early Observations of Type Ia Supernovae. III. Early-time Colors As a Test for Explosion Models and Multiple Populations2020Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 902, nr 1, artikkel-id 48Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Colors of Type Ia supernovae (SNe Ia) in the first few days after explosion provide a potential discriminant between different models. In this paper, we present g - r colors of 65 SNe Ia discovered within 5 days from first light by the Zwicky Transient Facility in 2018, a sample that is about three times larger than that in the literature. We find that g - r colors are intrinsically rather homogeneous at early phases, with about half of the dispersion attributable to photometric uncertainties (0.18 mag). Colors are nearly constant starting from 6 days after first light (g-r similar to -0.15 mag), while the time evolution at earlier epochs is characterized by a continuous range of slopes, from events rapidly transitioning from redder to bluer colors (slope of similar to-0.25 mag day(-1)) to events with a flatter evolution. The continuum in the slope distribution is in good agreement both with models requiring some amount of Ni-56 mixed in the outermost regions of the ejecta and with double-detonation models having thin helium layers (M-He = 0.01 M-circle dot) and varying carbon-oxygen core masses. At the same time, six events show evidence for a distinctive red bump signature predicted by double-detonation models with larger helium masses. We finally identify a significant correlation between the early-timeg - rslopes and supernova brightness, with brighter events associated to flatter color evolution (p-value = 0.006). The distribution of slopes, however, is consistent with being drawn from a single population, with no evidence for two components as claimed in the literature based on B - V colors.

  • 41. Cai, Y.-Z.
    et al.
    Pastorello, A.
    Fraser, M.
    Botticella, M.T.
    Elias-Rosa, N.
    Wang, L.-Z.
    Kotak, R.
    Benetti, S.
    Cappellaro, E.
    Turatto, M.
    Reguitti, A.
    Mattila, S.
    Smartt, S.J.
    Ashall, C.
    Benitez, S.
    Chen, Ting-Wan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Harutyunyan, A.
    Kankare, E.
    Lundqvist, Peter
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Mazzali, P.A.
    Morales-Garoffolo, A.
    Ochner, P.
    Pignata, G.
    Prentice, S.J.
    Reynolds, T.M.
    Shu, X.-W.
    Stritzinger, M. D.
    Tartaglia, L.
    Terreran, G.
    Tomasella, L.
    Valenti, S.
    Valerin, G.
    Wang, G.-J.
    Wang, X.-F.
    Borsato, L.
    Callis, E.
    Cannizzaro, G.
    Chen, S.
    Congiu, E.
    Ergon, Mattias
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Galbany, L.
    Gal-Yam, A.
    Gao, X.
    Gromadzki, M.
    Holmbo, S.
    Huang, F.
    Inserra, C.
    Itagaki, K.
    Kostrzewa-Rutkowska, Z.
    Maguire, K.
    Margheim, S.
    Moran, S.
    Onori, F.
    Sagués Carracedo, Ana
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Smith, K.W.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Somero, A.
    Wang, B.
    Young, D.R.
    Intermediate-luminosity red transients: Spectrophotometric properties and connection to electron-capture supernova explosions2021Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 654, artikkel-id A157Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present the spectroscopic and photometric study of five intermediate-luminosity red transients (ILRTs), namely AT 2010dn, AT 2012jc, AT 2013la, AT 2013lb, and AT 2018aes. They share common observational properties and belong to a family of objects similar to the prototypical ILRT SN 2008S. These events have a rise time that is less than 15 days and absolute peak magnitudes of between −11.5 and −14.5 mag. Their pseudo-bolometric light curves peak in the range 0.5–9.0 × 1040 erg s−1 and their total radiated energies are on the order of (0.3–3) × 1047 erg. After maximum brightness, the light curves show a monotonic decline or a plateau, resembling those of faint supernovae IIL or IIP, respectively. At late phases, the light curves flatten, roughly following the slope of the 56Co decay. If the late-time power source is indeed radioactive decay, these transients produce 56Ni masses on the order of 10−4 to 10−3M. The spectral energy distribution of our ILRT sample, extending from the optical to the mid-infrared (MIR) domain, reveals a clear IR excess soon after explosion and non-negligible MIR emission at very late phases. The spectra show prominent H lines in emission with a typical velocity of a few hundred km s−1, along with Ca II features. In particular, the [Ca II] λ7291,7324 doublet is visible at all times, which is a characteristic feature for this family of transients. The identified progenitor of SN 2008S, which is luminous in archival Spitzer MIR images, suggests an intermediate-mass precursor star embedded in a dusty cocoon. We propose the explosion of a super-asymptotic giant branch star forming an electron-capture supernova as a plausible explanation for these events.

  • 42. Campbell, Heather
    et al.
    D'Andrea, Chris B.
    Nichol, Robert C.
    Sako, Masao
    Smith, Mathew
    Lampeitl, Hubert
    Olmstead, Matthew D.
    Bassett, Bruce
    Biswas, Rahul
    Brown, Peter
    Cinabro, David
    Dawson, Kyle S.
    Dilday, Ben
    Foley, Ryan J.
    Frieman, Joshua A.
    Garnavich, Peter
    Hlozek, Renee
    Jha, Saurabh W.
    Kuhlmann, Steve
    Kunz, Martin
    Marriner, John
    Miquel, Ramon
    Richmond, Michael
    Riess, Adam
    Schneider, Donald P.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Taylor, Matt
    Zhao, Gong-Bo
    COSMOLOGY WITH PHOTOMETRICALLY CLASSIFIED TYPE Ia SUPERNOVAE FROM THE SDSS-II SUPERNOVA SURVEY2013Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 763, nr 2, s. 88-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present the cosmological analysis of 752 photometrically classified Type Ia Supernovae (SNe Ia) obtained from the full Sloan Digital Sky Survey II (SDSS-II) Supernova (SN) Survey, supplemented with host-galaxy spectroscopy from the SDSS-III Baryon Oscillation Spectroscopic Survey. Our photometric-classification method is based on the SN classification technique of Sako et al., aided by host-galaxy redshifts (0.05 < z < 0.55). SuperNova ANAlysis simulations of our methodology estimate that we have an SN Ia classification efficiency of 70.8%, with only 3.9% contamination from core-collapse (non-Ia) SNe. We demonstrate that this level of contamination has no effect on our cosmological constraints. We quantify and correct for our selection effects (e. g., Malmquist bias) using simulations. When fitting to a flat.CDM cosmological model, we find that our photometric sample alone gives Omega(m) = 0.24(-0.05)(+0.07) (statistical errors only). If we relax the constraint on flatness, then our sample provides competitive joint statistical constraints on Omega(m) and Omega(Lambda), comparable to those derived from the spectroscopically confirmed Three-year Supernova Legacy Survey (SNLS3). Using only our data, the statistics-only result favors an accelerating universe at 99.96% confidence. Assuming a constant wCDM cosmological model, and combining with H-0, cosmic microwave background, and luminous red galaxy data, we obtain w = -0.96(-0.10)(+0.10), Omega(m) = 0.29(-0.02)(+0.02), and Omega(k) = 0.00(-0.02)(+0.03)(statistical errors only), which is competitive with similar spectroscopically confirmed SNe Ia analyses. Overall this comparison is reassuring, considering the lower redshift leverage of the SDSS-II SN sample (z < 0.55) and the lack of spectroscopic confirmation used herein. These results demonstrate the potential of photometrically classified SN Ia samples in improving cosmological constraints.

  • 43. Cano, Z.
    et al.
    Izzo, L.
    de Ugarte Postigo, A.
    Thöne, C. C.
    Krühler, T.
    Heintz, K. E.
    Malesani, D.
    Geier, S.
    Fuentes, C.
    Chen, T. -W.
    Covino, S.
    D'Elia, V.
    Fynbo, J. P. U.
    Goldoni, P.
    Gomboc, A.
    Hjorth, J.
    Jakobsson, P.
    Kann, D. A.
    Milvang-Jensen, B.
    Pugliese, G.
    Sánchez-Ramírez, R.
    Schulze, S.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Tanvir, N. R.
    Wiersema, K.
    GRB 161219B/SN 2016jca: A low-redshift gamma-ray burst supernova powered by radioactive heating2017Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 605, artikkel-id A107Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Since the first discovery of a broad-lined type Ic supernova (SN) with a long-duration gamma-ray burst (GRB) in 1998, fewer than fifty GRB-supernovae (SNe) have been discovered. The intermediate-luminosity Swift GRB 161219B and its associated supernova SN 2016jca, which occurred at a redshift of z = 0.1475, represents only the seventh GRB-SN to have been discovered within 1 Gpc, and hence provides an excellent opportunity to investigate the observational and physical properties of these very elusive and rare type of SN. As such, we present optical to near-infrared photometry and optical spectroscopy of GRB 161219B and SN 2016jca, spanning the first three months since its discovery. GRB 161219B exploded in the disk of an edge-on spiral galaxy at a projected distance of 3.4 kpc from the galactic centre. GRB 161219B itself is an outlier in the E-p,E-i - E-gamma,E-iso plane, while SN 2016jca had a rest-frame, peak absolute V-band magnitude of M-V = -19.0 +/- 0.1, which it reached after 12.3 +/- 0.7 rest-frame days. We find that the bolometric properties of SN 2016jca are inconsistent with being powered solely by a magnetar central engine, and demonstrate that it was likely powered exclusively by energy deposited by the radioactive decay of nickel and cobalt into their daughter products, which were nucleosynthesised when its progenitor underwent core collapse. We find that 0.22 +/- 0.08 M-circle dot of nickel is required to reproduce the peak luminosity of SN 2016jca, and we constrain an ejecta mass of 5.8 +/- 0.3 M-circle dot and a kinetic energy of 5.1 +/- 0.8 x 10(52) erg. Finally, we report on a chromatic, pre-maximum bump in the g-band light curve, and discuss its possible origin.

  • 44. Cao, Yi
    et al.
    Kulkarni, S. R.
    Howell, D. Andrew
    Gal-Yam, Avishay
    Kasliwal, Mansi M.
    Valenti, Stefano
    Johansson, Joel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Amanullah, Rahman
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Goobar, Ariel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Taddia, Francesco
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Horesh, Assaf
    Sagiv, Ilan
    Cenko, S. Bradley
    Nugent, Peter E.
    Arcavi, Iair
    Surace, Jason
    Wozniak, P. R.
    Moody, Daniela I.
    Rebbapragada, Umaa D.
    Bue, Brian D.
    Gehrels, Neil
    A strong ultraviolet pulse from a newborn type Ia supernova2015Inngår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 521, nr 7552, s. 328-+Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Type Ia supernovae(1) are destructive explosions of carbon-oxygen white dwarfs(2,3). Although they are used empirically to measure cosmological distances(4-6), the nature of their progenitors remains mysterious(3). One of the leading progenitor models, called the single degenerate channel, hypothesizes that a white dwarf accretes matter from a companion star and the resulting increase in its central pressure and temperature ignites thermonuclear explosion(3,7,8). Here we report observations with the Swift Space Telescope of strong but declining ultraviolet emission from a type Ia supernova within four days of its explosion. This emission is consistent with theoretical expectations of collision between material ejected by the supernova and a companion star(9), and therefore provides evidence that some type Ia supernovae arise from the single degenerate channel.

  • 45. Charalampopoulos, P.
    et al.
    Leloudas, G.
    Malesani, D. B.
    Wevers, T.
    Arcavi, I.
    Nicholl, M.
    Pursiainen, M.
    Lawrence, A.
    Anderson, J. P.
    Benetti, S.
    Cannizzaro, G.
    Chen, Ting-Wan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Galbany, L.
    Gromadzki, M.
    Gutiérrez, C. P.
    Inserra, C.
    Jonker, P. G.
    Müller-Bravo, T. E.
    Onori, F.
    Short, P.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Young, D. R.
    A detailed spectroscopic study of tidal disruption events2022Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 659, artikkel-id A34Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Spectroscopically, tidal disruption events (TDEs) are characterized by broad (similar to 10(4) km s(-1)) emission lines and show a large diversity as well as different line profiles. After carefully and consistently performing a series of data reduction tasks including host galaxy light subtraction, we present here the first detailed, spectroscopic population study of 16 optical and UV TDEs. We study a number of emission lines prominent among TDEs including Hydrogen, Helium, and Bowen lines and we quantify their evolution with time in terms of line luminosities, velocity widths, and velocity offsets. We report a time lag between the peaks of the optical light curves and the peak luminosity of H alpha spanning between similar to 7 and 45 days. If interpreted as light echoes, these lags correspond to distances of similar to 2 - 12 x 10(16) cm, which are one to two orders of magnitudes larger than the estimated blackbody radii (R-BB) of the same TDEs and we discuss the possible origin of this surprisingly large discrepancy. We also report time lags for the peak luminosity of the He I 5876 angstrom line, which are smaller than the ones of H alpha for H TDEs and similar or larger for N III Bowen TDEs. We report that N III Bowen TDEs have lower H alpha velocity widths compared to the rest of the TDEs in our sample and we also find that a strong X-ray to optical ratio might imply weakening of the line widths. Furthermore, we study the evolution of line luminosities and ratios with respect to their radii (R-BB) and temperatures (T-BB). We find a linear relationship between H alpha luminosity and the R-BB (L-line proportional to R-BB) and potentially an inverse power-law relation with T-BB (L-line proportional to T-BB(-beta)), leading to weaker H alpha emission for T-BB >= 25 000 K. The He II/He I ratio becomes large at the same temperatures, possibly pointing to an ionization effect. The He II/H alpha ratio becomes larger as the photospheric radius recedes, implying a stratified photosphere where Helium lies deeper than Hydrogen. We suggest that the large diversity of the spectroscopic features seen in TDEs along with their X-ray properties can potentially be attributed to viewing angle effects.

  • 46. Chen, Ping
    et al.
    Gal-Yam, Avishay
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Schulze, Steve
    Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Post, Richard S.
    Liu, Chang
    Ofek, Eran O.
    Das, Kaustav K.
    Fremling, Christoffer
    Horesh, Assaf
    Katz, Boaz
    Kushnir, Doron
    Kasliwal, Mansi M.
    Kulkarni, Shri R.
    Liu, Dezi
    Liu, Xiangkun
    Miller, Adam A.
    Rose, Kovi
    Waxman, Eli
    Yang, Sheng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Henan Academy of Sciences, People’s Republic of China.
    Yao, Yuhan
    Zackay, Barak
    Bellm, Eric C.
    Dekany, Richard
    Drake, Andrew J.
    Fang, Yuan
    Fynbo, Johan P. U.
    Groom, Steven L.
    Helou, George
    Irani, Ido
    Jegou du Laz, Theophile
    Liu, Xiaowei
    Mazzali, Paolo A.
    Neill, James D.
    Qin, Yu-Jing
    Riddle, Reed L.
    Sharon, Amir
    Strotjohann, Nora L.
    Wold, Avery
    Yan, Lin
    A 12.4-day periodicity in a close binary system after a supernova2024Inngår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 625, nr 7994, s. 253-258Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Neutron stars and stellar-mass black holes are the remnants of massive star explosions1. Most massive stars reside in close binary systems2, and the interplay between the companion star and the newly formed compact object has been theoretically explored3, but signatures for binarity or evidence for the formation of a compact object during a supernova explosion are still lacking. Here we report a stripped-envelope supernova, SN 2022jli, which shows 12.4-day periodic undulations during the declining light curve. Narrow Hα emission is detected in late-time spectra with concordant periodic velocity shifts, probably arising from hydrogen gas stripped from a companion and accreted onto the compact remnant. A new Fermi-LAT γ-ray source is temporally and positionally consistent with SN 2022jli. The observed properties of SN 2022jli, including periodic undulations in the optical light curve, coherent Hα emission shifting and evidence for association with a γ-ray source, point to the explosion of a massive star in a binary system leaving behind a bound compact remnant. Mass accretion from the companion star onto the compact object powers the light curve of the supernova and generates the γ-ray emission.

  • 47. Chen, T.-W.
    et al.
    Inserra, C.
    Fraser, M.
    Moriya, T. J.
    Schady, P.
    Schweyer, T.
    Filippenko, A.
    Perley, D. A.
    Ruiter, A. J.
    Seitenzahl, I.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Taddia, Francesco
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Anderson, J. P.
    Foley, R. J.
    Jerkstrand, A.
    Ngeow, C.-C.
    Pan, Y.-C.
    Pastorello, A.
    Points, S.
    Smartt, S. J.
    Smith, K. W.
    Taubenberger, S.
    Wienlan, P.
    Young, D. R.
    Benetti, S.
    Berton, M.
    Bufano, F.
    Clark, P.
    Della Valle, M.
    Galbany, L.
    Gal-Yam, A.
    Gromadzki, M.
    Gutierrez, C. P.
    Heinze, A.
    Kankare, E.
    Kilpatrick, C. D.
    Kuncarayakti, H.
    Leloudas, G.
    Lin, Z.-Y.
    Maguire, K.
    Mazzali, P.
    McBrien, O.
    Prentice, S. J.
    Rau, A.
    Rest, A.
    Siebert, M. R.
    Stalder, B.
    Tonry, J. L.
    Yu, P.-C.
    SN 2017ens: The Metamorphosis of a Luminous Broadlined Type Ic Supernova into an SN IIn2018Inngår i: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 867, nr 2, artikkel-id L31Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present observations of supernova (SN) 2017ens, discovered by the ATLAS survey and identified as a hot blue object through the GREAT program. The redshift z = 0.1086 implies a peak brightness of M-g = -21.1 mag, placing the object within the regime of superluminous supernovae. We observe a dramatic spectral evolution, from initially being blue and featureless, to later developing features similar to those of the broadlined Type Ic SN 1998bw, and finally showing 2000 km s(-1) wide H alpha and H beta emission. Relatively narrow Balmer emission (reminiscent of a SN IIn) is present at all times. We also detect coronal lines, indicative of a dense circumstellar medium. We constrain the progenitor wind velocity to similar to 50-60 km s(-1) based on P-Cygni profiles, which is far slower than those present in Wolf-Rayet stars. This may suggest that the progenitor passed through a luminous blue variable phase, or that the wind is instead from a binary companion red supergiant star. At late times we see the similar to 2000 km s(-1) wide H alpha emission persisting at high luminosity (similar to 3 x 10(40) erg s(-1)) for at least 100 day, perhaps indicative of additional mass loss at high velocities that could have been ejected by a pulsational pair instability.

  • 48. Chen, Z. H.
    et al.
    Yan, Lin
    Kangas, T.
    Lunnan, Ragnhild
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Schulze, Steve
    Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Perley, D. A.
    Chen, Ting-Wan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Taggart, K.
    Hinds, K. R.
    Gal-Yam, A.
    Wang, X. F.
    Andreoni, I.
    Bellm, E.
    Bloom, J. S.
    Burdge, K.
    Burgos, A.
    Cook, D.
    Dahiwale, A.
    De, K.
    Dekany, R.
    Dugas, A.
    Frederik, S.
    Fremling, C.
    Graham, M.
    Hankins, M.
    Ho, A.
    Jencson, J.
    Karambelkar, V.
    Kasliwal, M.
    Kulkarni, S.
    Laher, R.
    Rusholme, B.
    Sharma, Y.
    Taddia, F.
    Tartaglia, L.
    Thomas, B. P.
    Tzanidakis, A.
    Van Roestel, J.
    Walter, R.
    Yang, Y.
    Yao, Y. H.
    Yaron, O.
    The Hydrogen-poor Superluminous Supernovae from the Zwicky Transient Facility Phase I Survey. I. Light Curves and Measurements2023Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 943, nr 1, artikkel-id 41Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During the Zwicky Transient Facility (ZTF) Phase I operations, 78 hydrogen-poor superluminous supernovae (SLSNe-I) were discovered in less than 3 yr, constituting the largest sample from a single survey. This paper (Paper I) presents the data, including the optical/UV light curves and classification spectra, while Paper II in this series will focus on the detailed analysis of the light curves and modeling. Our photometry is primarily taken by ZTF in the g, r, and i bands, and with additional data from other ground-based facilities and Swift. The events of our sample cover a redshift range of z = 0.06 − 0.67, with a median and 1σ error (16% and 84% percentiles) of zmed=0.265. The peak luminosity covers −22.8 mag ≤ Mg,peak ≤ −19.8 mag, with a median value of -21.48. The light curves evolve slowly with a mean rest-frame rise time of trise = 41.9 ± 17.8 days. The luminosity and timescale distributions suggest that low-luminosity SLSNe-I with a peak luminosity ∼−20 mag or extremely fast-rising events (<10 days) exist, but are rare. We confirm previous findings that slowly rising SLSNe-I also tend to fade slowly. The rest-frame color and temperature evolution show large scatters, suggesting that the SLSN-I population may have diverse spectral energy distributions. The peak rest-frame color shows a moderate correlation with the peak absolute magnitude, i.e., brighter SLSNe-I tend to have bluer colors. With optical and UV photometry, we construct the bolometric luminosity and derive a bolometric correction relation that is generally applicable for converting g, r-band photometry to the bolometric luminosity for SLSNe-I.

  • 49. Chen, Z. H.
    et al.
    Yan, Lin
    Kangas, T.
    Lunnan, Ragnhild
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Schulze, Steve
    Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Perley, D. A.
    Chen, Ting-Wan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Taggart, K.
    Hinds, K. R.
    Gal-Yam, A.
    Wang, X. F.
    De, K.
    Bellm, E.
    Bloom, J. S.
    Dekany, R.
    Graham, M.
    Kasliwal, M.
    Kulkarni, S.
    Laher, R.
    Neill, D.
    Rusholme, B.
    The Hydrogen-poor Superluminous Supernovae from the Zwicky Transient Facility Phase I Survey. II. Light-curve Modeling and Characterization of Undulations2023Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 943, nr 1, artikkel-id 42Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present analysis of the light curves (LCs) of 77 hydrogen-poor superluminous supernovae (SLSNe I) discovered during the Zwicky Transient Facility Phase I operation. We find that the majority (67%) of the sample can be fit equally well by both magnetar and ejecta–circumstellar medium (CSM) interaction plus 56Ni decay models. This implies that LCs alone cannot unambiguously constrain the physical power sources for an SLSN I. However, 23% of the sample show inverted V-shape, steep-declining LCs or features of long rise and fast post-peak decay, which are better described by the CSM+Ni model. The remaining 10% of the sample favors the magnetar model. Moreover, our analysis shows that the LC undulations are quite common, with a fraction of 18%–44% in our gold sample. Among those strongly undulating events, about 62% of them are found to be CSM-favored, implying that the undulations tend to occur in the CSM-favored events. Undulations show a wide range in energy and duration, with median values (and 1σ errors) being as  and  days, respectively. Our analysis of the undulation timescales suggests that intrinsic temporal variations of the central engine can explain half of the undulating events, while CSM interaction (CSI) can account for the majority of the sample. Finally, all of the well-observed He-rich SLSNe Ib either have strongly undulating LCs or the LCs are much better fit by the CSM+Ni model. These observations imply that their progenitor stars have not had enough time to lose all of the He-envelopes before supernova explosions, and H-poor CSM are likely to present in these events.

  • 50. Childress, M. J.
    et al.
    Hillier, D. J.
    Seitenzahl, I.
    Sullivan, M.
    Maguire, K.
    Taubenberger, S.
    Scalzo, R.
    Ruiter, A.
    Blagorodnova, N.
    Camacho, Y.
    Castillo, J.
    Elias-Rosa, N.
    Fraser, M.
    Gal-Yam, A.
    Graham, M.
    Howell, D. A.
    Inserra, C.
    Jha, S. W.
    Kumar, S.
    Mazzali, P. A.
    McCully, C.
    Morales-Garoffolo, A.
    Pandya, V.
    Polshaw, J.
    Schmidt, B.
    Smartt, S.
    Smith, K. W.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Spyromilio, J.
    Tucker, B.
    Valenti, S.
    Walton, N.
    Wolf, C.
    Yaron, O.
    Young, D. R.
    Yuan, F.
    Zhang, B.
    Measuring nickel masses in Type Ia supernovae using cobalt emission in nebular phase spectra2015Inngår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 454, nr 4, s. 3816-3842Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The light curves of Type Ia supernovae (SNe Ia) are powered by the radioactive decay of Ni-56 to Co-56 at early times, and the decay of Co-56 to Fe-56 from similar to 60 d after explosion. We examine the evolution of the [Co III] lambda 5893 emission complex during the nebular phase for SNe Ia with multiple nebular spectra and show that the line flux follows the square of the mass of Co-56 as a function of time. This result indicates both efficient local energy deposition from positrons produced in Co-56 decay and long-term stability of the ionization state of the nebula. We compile SN Ia nebular spectra from the literature and present 21 new late-phase spectra of 7 SNe Ia, including SN 2014J. From these we measure the flux in the [Co III] lambda 5893 line and remove its well-behaved time dependence to infer the initial mass of Ni-56 (M-Ni, produced in the explosion. We then examine Ni-56 yields for different SN Ia ejected masses (M-ej-calculated using the relation between light-curve width and ejected mass) and find that the Ni-56 masses of SNe Ia fall into two regimes: for narrow light curves (low stretch s similar to 0.7-0.9), M-Ni is clustered near MN, 0.4 Me and shows a shallow increase as Mei increases from similar to 1 to 1.4 M-circle dot; at high stretch, M-ej clusters at the Chandrasekhar mass (1.4 M-circle dot) while M-Ni, spans a broad range from 0.6 to 1.2 M-circle dot. This could constitute evidence for two distinct SN Ia explosion mechanisms.

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