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  • 51. Christensen,
    et al.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    IFU observations of the GRB 980425/SN 1998bw host galaxy: emission line ratios in GRB regions2008Inngår i: Astronomy and AstrophysicsArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Context. The collapsar model predicts that the progenitors of Gamma-ray Bursts (GRBs) are metal poor in Fe group elements. The existence of low metallicity stellar populations could manifest itself in the characteristics of the GRB site immediate environment in the host galaxy.

    Aims. We analyse the strong emission lines from the sub-luminous host galaxy of GRB 980425, which showed the first connection with a supernova explosion (SN 1998bw). The host is of sufficient size to allow detailed resolved spectroscopy of individual H II regions and to search for regions with peculiar properties close to the the GRB site.

    Methods. Using integral field spectroscopy with VIMOS we study most of the high surface brightness part of the host including the H II region where the supernova and GRB occurred.

    Results. The star formation rate, reddening, equivalent width and stellar mass in the GRB region is similar to other H II regions in the host. Extreme values arise in the only region that shows emission lines from Wolf-Rayet stars, a region that is located 800 pc in projection from the GRB site. Strong emission line diagnostics of all H II regions imply oxygen abundances between 0.3 and 0.8 solar with the lowest values arising in the WR and GRB regions. Including uncertainties from the metallicity diagnostics, all metallicities are similar to within 3$\sigma $. We demonstrate that there is a good agreement between the luminosity weighted and mass weighted specific star formation rates (SSFR) in individual young H II regions. While the global average of the SSFR is similar to high redshift GRB hosts, there are significant variations between individual resolved H II regions. Comparing the measured emission line ratios of low redshift GRB hosts to theoretical models and observations of field galaxies, we find that GRBs are present in different environment metallicities while the regions of their origin are consistently very young. Similar line ratios of GRB hosts compared with those of the WR region can arise in spatially unresolved galaxies with bright H II regions close to the GRB location.

  • 52. Chugai, Nikolai N.
    et al.
    Blinnikov, Sergei I.
    Cumming, Robert J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Lundqvist, Peter
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Bragaglia, Angela
    Filippenko, Alexei V.
    Leonard, Douglas C.
    Matheson, Thomas
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    The Type IIn supernova 1994W: evidence for the explosive ejection of a circumstellar envelope2004Inngår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 352, s. 1213-1231Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present and analyse spectra of the Type IIn supernova (SN) 1994W obtained between 18 and 203d after explosion. During the luminous phase (first 100d) the line profiles are composed of three major components: (i) narrow P-Cygni lines with the absorption minima at -700kms-1 (ii) broad emission lines with blue velocity at zero intensity ~4000km s-1 and (iii) broad, smooth wings extending out to at least ~5000kms-1, most apparent in Hα. These components are identified with an expanding circumstellar (CS) envelope, shocked cool gas in the forward post-shock region, and multiple Thomson scattering in the CS envelope, respectively. The absence of broad P-Cygni lines from the SN is the result of the formation of an optically thick, cool, dense shell at the interface of the ejecta and the CS envelope. Models of the SN deceleration and Thomson scattering wings are used to recover the density (n~ 109cm-3), radial extent [~(4-5) × 1015cm] and Thomson optical depth (τT>~ 2.5) of the CS envelope during the first month. The plateau-like SN light curve is reproduced by a hydrodynamical model and is found to be powered by a combination of internal energy leakage after the explosion of an extended pre-SN (~1015cm) and subsequent luminosity from CS interaction. The pre-explosion kinematics of the CS envelope is recovered, and is close to homologous expansion with outer velocity ~1100kms-1 and a kinematic age of ~1.5yr. The high mass (~0.4Msolar) and kinetic energy (~2 × 1048erg) of the CS envelope, combined with low age, strongly suggest that the CS envelope was explosively ejected ~1.5yr prior to the SN explosion.

  • 53. Ciabattari, F.
    et al.
    Mazzoni, E.
    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.
    Supernova 2012eh in IC 1706 = Psn J01273145+14490582012Rapport (Annet vitenskapelig)
    Abstract [en]

    CBET 3208 available at Central Bureau for Astronomical Telegrams.

  • 54. Clark, Peter
    et al.
    Maguire, Kate
    Inserra, Cosimo
    Prentice, Simon
    Smartt, Stephen J.
    Contreras, Carlos
    Hossenizadeh, Griffin
    Hsiao, Eric Y.
    Kankare, Erkki
    Kasliwal, Mansi
    Nugent, Peter
    Shahbandeh, Melissa
    Baltay, Charles
    Rabinowitz, David
    Arcavi, Iair
    Ashall, Chris
    Burns, Christopher R.
    Callis, Emma
    Chen, Ting-Wan
    Diamond, Tiara
    Fraser, Morgan
    Howell, D. Andrew
    Karamehmetoglu, Emir
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kotak, Rubina
    Lyman, Joseph
    Morrell, Nidia
    Phillips, Mark
    Pignata, Giuliano
    Pursiainen, Miika
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Stritzinger, Maximilian
    Sullivan, Mark
    Young, David
    LSQ13ddu: a rapidly evolving stripped-envelope supernova with early circumstellar interaction signatures2020Inngår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 492, nr 2, s. 2208-2228Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper describes the rapidly evolving and unusual supernova LSQ13ddu, discovered by the La Silla-QUEST survey. LSQ13ddu displayed a rapid rise of just 4.8 +/- 0.9 d to reach a peak brightness of -19.70 +/- 0.02 mag in the LSQgr band. Early spectra of LSQ13ddu showed the presence of weak and narrow He I features arising from interaction with circumstellar material (CSM). These interaction signatures weakened quickly, with broad features consistent with those seen in stripped-envelope SNe becoming dominant around two weeks after maximum. The narrow He I velocities are consistent with the wind velocities of luminous blue variables but its spectra lack the typically seen hydrogen features. The fast and bright early light curve is inconsistent with radioactive Ni-56 powering but can be explained through a combination of CSM interaction and an underlying Ni-56 decay component that dominates the later time behaviour of LSQ13ddu. Based on the strength of the underlying broad features, LSQ13ddu appears deficient in He compared to standard SNe Ib.

  • 55. Corsi, Alessandra
    et al.
    Cenko, S. B.
    Kasliwal, M. M.
    Quimby, Robert
    Kulkarni, S. R.
    Frail, D. A.
    Goldstein, A. M.
    Blagorodnova, N.
    Connaughton, V.
    Perley, D. A.
    Singer, L. P.
    Copperwheat, C. M.
    Fremling, Christoffer
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kupfer, T.
    Piascik, A. S.
    Steele, I. A.
    Taddia, Francesco
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Vedantham, H.
    Kutyrev, A.
    Palliyaguru, N. T.
    Roberts, O.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Troja, E.
    Veilleux, S.
    iPTF17cw: An Engine-driven Supernova Candidate Discovered Independent of a Gamma-Ray Trigger2017Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 847, nr 1, artikkel-id 54Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present the discovery, classification, and radio-to-X-ray follow-up observations of iPTF17cw, a broad-lined (BL) type Ic supernova (SN) discovered by the intermediate Palomar Transient Factory (iPTF). Although it is unrelated to the gravitational wave trigger, this SN was discovered as a happy by-product of the extensive observational campaign dedicated to the follow-up of Advanced LIGO event GW 170104. The spectroscopic properties and inferred peak bolometric luminosity of iPTF17cw are most similar to the gamma-ray-burst (GRB)associated SN, SN 1998bw, while the shape of the r-band light curve is most similar to that of the relativistic SN, SN 2009bb. Karl G. Jansky Very Large Array (VLA) observations of the iPTF17cw field reveal a radio counterpart approximate to 10 times less luminous than SN 1998bw, and with a peak radio luminosity comparable to that of SN 2006aj/GRB 060218 and SN 2010bh/GRB 100316D. Our radio observations of iPTF17cw imply a relativistically expanding outflow. However, further late-time observations with the VLA in its most extended configuration are needed to confirm fading of the iPTF17cw radio counterpart at all frequencies. X-ray observations carried out with Chandra reveal the presence of an X-ray counterpart with a luminosity similar to that of SN 2010bh/GRB 100316D. Searching the Fermi catalog for possible gamma-rays reveals that GRB 161228B is spatially and temporally compatible with iPTF17cw. The similarity to SN 1998bw and SN 2009bb, the radio and X-ray detections, and the potential association with GRB 161228B all point to iPTF17cw being a new candidate member of the rare sample of optically discovered engine-driven BL-Ic SNe associated with relativistic ejecta.

  • 56. Corsi, Alessandra
    et al.
    Ho, Anna Y. Q.
    Cenko, S. Bradley
    Kulkarni, Shrinivas R.
    Anand, Shreya
    Yang, Sheng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Henan Academy of Sciences, China.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Srinivasaragavan, Gokul P.
    Omand, Conor M. B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Balasubramanian, Arvind
    Frail, Dale A.
    Fremling, Christoffer
    Perley, Daniel A.
    Yao, Yuhan
    Dahiwale, Aishwarya S.
    De, Kishalay
    Dugas, Alison
    Hankins, Matthew
    Jencson, Jacob
    Kasliwal, Mansi M.
    Tzanidakis, Anastasios
    Bellm, Eric C.
    Laher, Russ R.
    Masci, Frank J.
    Purdum, Josiah N.
    Regnault, Nicolas
    A Search for Relativistic Ejecta in a Sample of ZTF Broad-lined Type Ic Supernovae2023Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 953, nr 2, artikkel-id 179Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The dividing line between gamma-ray bursts (GRBs) and ordinary stripped-envelope core-collapse supernovae (SNe) is yet to be fully understood. Observationally mapping the variety of ejecta outcomes (ultrarelativistic, mildly relativistic, or nonrelativistic) in SNe of Type Ic with broad lines (Ic-BL) can provide a key test to stellar explosion models. However, this requires large samples of the rare SN Ic-BL events with follow-up observations in the radio, where fast ejecta can be probed largely free of geometry and viewing angle effects. Here, we present the results of a radio (and X-ray) follow-up campaign of 16 SNe Ic-BL detected by the Zwicky Transient Facility (ZTF). Our radio campaign resulted in four counterpart detections and 12 deep upper limits. None of the events in our sample is as relativistic as SN 1998bw and we constrain the fraction of SN 1998bw-like explosions to <19% (3σ Gaussian equivalent), a factor of ≈2 smaller than previously established. We exclude relativistic ejecta with radio luminosity densities in between ≈5 × 1027 erg s−1 Hz−1 and ≈1029 erg s−1 Hz−1 at t ≳ 20 days since explosion for ≈60% of the events in our sample. This shows that SNe Ic-BL similar to the GRB-associated SNe 1998bw, 2003lw, and 2010bh, or to the relativistic SNe 2009bb and iPTF17cw, are rare. Our results also exclude an association of the SNe Ic-BL in our sample with largely off-axis GRBs with energies E ≳ 1050 erg. The parameter space of SN 2006aj-like events (faint and fast-peaking radio emission) is, on the other hand, left largely unconstrained, and systematically exploring it represents a promising line of future research.

  • 57. Coughlin, Michael W.
    et al.
    Ahumada, Tomas
    Anand, Shreya
    De, Kishalay
    Hankins, Matthew J.
    Kasliwal, Mansi M.
    Singer, Leo P.
    Bellm, Eric C.
    Andreoni, Igor
    Cenko, S. Bradley
    Cooke, Jeff
    Copperwheat, Christopher M.
    Dugas, Alison M.
    Jencson, Jacob E.
    Perley, Daniel A.
    Yu, Po-Chieh
    Bhalerao, Varun
    Kumar, Harsh
    Bloom, Joshua S.
    Anupama, G. C.
    Ashley, Michael C. B.
    Bagdasaryan, Ashot
    Biswas, Rahul
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Buckley, David A. H.
    Burdge, Kevin B.
    Cook, David O.
    Cromer, John
    Cunningham, Virginia
    D'Ai, Antonino
    Dekany, Richard G.
    Delacroix, Alexandre
    Dichiara, Simone
    Duev, Dmitry A.
    Dutta, Anirban
    Feeney, Michael
    Frederick, Sara
    Gatkine, Pradip
    Ghosh, Shaon
    Goldstein, Daniel A.
    Golkhou, V. Zach
    Goobar, Ariel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Graham, Matthew J.
    Hanayama, Hidekazu
    Horiuchi, Takashi
    Hung, Tiara
    Jha, Saurabh W.
    Kong, Albert K. H.
    Giomi, Matteo
    Kaplan, David L.
    Karambelkar, V. R.
    Kowalski, Marek
    Kulkarni, Shrinivas R.
    Kupfer, Thomas
    Masci, Frank J.
    Mazzali, Paolo
    Moore, Anna M.
    Mogotsi, Moses
    Neill, James D.
    Ngeow, Chow-Choong
    Martinez-Palomera, Jorge
    La Parola, Valentina
    Pavana, M.
    Ofek, Eran O.
    Patil, Atharva Sunil
    Riddle, Reed
    Rigault, Mickael
    Rusholme, Ben
    Serabyn, Eugene
    Shupe, David L.
    Sharma, Yashvi
    Singh, Avinash
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Soon, Jamie
    Staats, Kai
    Taggart, Kirsty
    Tan, Hanjie
    Travouillon, Tony
    Troja, Eleonora
    Waratkar, Gaurav
    Yatsu, Yoichi
    GROWTH on S190425z: Searching Thousands of Square Degrees to Identify an Optical or Infrared Counterpart to a Binary Neutron Star Merger with the Zwicky Transient Facility and Palomar Gattini-IR2019Inngår i: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 885, nr 1, artikkel-id L19Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The third observing run by LVC has brought the discovery of many compact binary coalescences. Following the detection of the first binary neutron star merger in this run (LIGO/Virgo S190425z), we performed a dedicated follow-up campaign with the Zwicky Transient Facility (ZTF) and Palomar Gattini-IR telescopes. The initial skymap of this single-detector gravitational wave (GW) trigger spanned most of the sky observable from Palomar Observatory. Covering 8000 deg(2) of the initial skymap over the next two nights, corresponding to 46% integrated probability, ZTF system achieved a depth of 21 m(AB) in g- and r-bands. Palomar Gattini-IR covered 2200 square degrees in J-band to a depth of 15.5 mag, including 32% integrated probability based on the initial skymap. The revised skymap issued the following day reduced these numbers to 21% for the ZTF and 19% for Palomar Gattini-IR. We narrowed 338,646 ZTF transient ?alerts? over the first two nights of observations to 15 candidate counterparts. Two candidates, ZTF19aarykkb and ZTF19aarzaod, were particularly compelling given that their location, distance, and age were consistent with the GW event, and their early optical light curves were photometrically consistent with that of kilonovae. These two candidates were spectroscopically classified as young core-collapse supernovae. The remaining candidates were ruled out as supernovae. Palomar Gattini-IR did not identify any viable candidates with multiple detections only after merger time. We demonstrate that even with single-detector GW events localized to thousands of square degrees, systematic kilonova discovery is feasible.

  • 58. Coughlin, Michael W.
    et al.
    Ahumada, Tomas
    Cenko, S. Bradley
    Cunningham, Virginia
    Ghosh, Shaon
    Singer, Leo P.
    Bellm, Eric C.
    Burns, Eric
    De, Kishalay
    Goldstein, Adam
    Golkhou, V. Zach
    Kaplan, David L.
    Kasliwal, Mansi M.
    Perley, Daniel A.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bagdasaryan, Ashot
    Dekany, Richard G.
    Duev, Dmitry A.
    Feeney, Michael
    Graham, Matthew J.
    Hale, David
    Kulkarni, Shri R.
    Kupfer, Thomas
    Laher, Russ R.
    Mahabal, Ashish
    Masci, Frank J.
    Miller, Adam A.
    Neill, James D.
    Patterson, Maria T.
    Riddle, Reed
    Rusholme, Ben
    Smith, Roger
    Tachibana, Yutaro
    Walters, Richard
    2900 Square Degree Search for the Optical Counterpart of Short Gamma-Ray Burst GRB 180523B with the Zwicky Transient Facility2019Inngår i: Publications of the Astronomical Society of the Pacific, ISSN 0004-6280, E-ISSN 1538-3873, Vol. 131, nr 998, artikkel-id 048001Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is significant interest in the models for production of short gamma-ray bursts (GRBs). Until now, the number of known short GRBs with multi-wavelength afterglows has been small. While the Fermi GRB Monitor detects many GRBs relative to the Neil Gehrels Swift Observatory, the large localization regions makes the search for counterparts difficult. With the Zwicky Transient Facility (ZTF) recently achieving first light, it is now fruitful to use its combination of depth (m(AB) similar to 20.6), field of view (approximate to 47 square degrees), and survey cadence (every similar to 3 days) to perform Target of Opportunity observations. We demonstrate this capability on GRB 180523B, which was recently announced by the Fermi GRB Monitor as a short GRB. ZTF imaged approximate to 2900 square degrees of the localization region, resulting in the coverage of 61.6% of the enclosed probability over two nights to a depth of m(AB) similar to 20.5. We characterized 14 previously unidentified transients, and none were found to be consistent with a short GRB counterpart. This search with the ZTF shows it is an efficient camera for searching for coarsely localized short GRB and gravitational-wave counterparts, allowing for a sensitive search with minimal interruption to its nominal cadence.

  • 59. Coughlin, Michael W.
    et al.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Sharma, Vyom
    A Data Science Platform to Enable Time-domain Astronomy2023Inngår i: Astrophysical Journal Supplement Series, ISSN 0067-0049, E-ISSN 1538-4365, Vol. 267, nr 2, artikkel-id 31Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    SkyPortal is an open-source software package designed to discover interesting transients efficiently, manage follow-up, perform characterization, and visualize the results. By enabling fast access to archival and catalog data, crossmatching heterogeneous data streams, and the triggering and monitoring of on-demand observations for further characterization, a SkyPortal-based platform has been operating at scale for >2 yr for the Zwicky Transient Facility Phase II community, with hundreds of users, containing tens of millions of time-domain sources, interacting with dozens of telescopes, and enabling community reporting. While SkyPortal emphasizes rich user experiences across common front-end workflows, recognizing that scientific inquiry is increasingly performed programmatically, SkyPortal also surfaces an extensive and well-documented application programming interface system. From back-end and front-end software to data science analysis tools and visualization frameworks, the SkyPortal design emphasizes the reuse and leveraging of best-in-class approaches, with a strong extensibility ethos. For instance, SkyPortal now leverages ChatGPT large language models to generate and surface source-level human-readable summaries automatically. With the imminent restart of the next generation of gravitational-wave detectors, SkyPortal now also includes dedicated multimessenger features addressing the requirements of rapid multimessenger follow-up: multitelescope management, team/group organizing interfaces, and crossmatching of multimessenger data streams with time-domain optical surveys, with interfaces sufficiently intuitive for newcomers to the field. This paper focuses on the detailed implementations, capabilities, and early science results that establish SkyPortal as a community software package ready to take on the data science challenges and opportunities presented by this next chapter in the multimessenger era.

  • 60. Czekala, Ian
    et al.
    Berger, E.
    Chornock, R.
    Pastorello, A.
    Marion, G. H.
    Margutti, R.
    Botticella, M. T.
    Challis, P.
    Ergon, Mattias
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Smartt, S.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Vinko, J.
    Wheeler, J. C.
    THE UNUSUALLY LUMINOUS EXTRAGALACTIC NOVA SN 2010U2013Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 765, nr 1, s. 57-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present observations of the unusual optical transient SN 2010U, including spectra taken 1.03 days to 15.3 days after maximum light that identify it as a fast and luminous Fe II type nova. Our multi-band light curve traces the fast decline (t(2) = 3.5 +/- 0.3 days) from maximum light (M-V = -10.2 +/- 0.1 mag), placing SN 2010U in the top 0.5% of the most luminous novae ever observed. We find typical ejecta velocities of approximate to 1100 km s(-1) and that SN 2010U shares many spectral and photometric characteristics with two other fast and luminous Fe II type novae, including Nova LMC 1991 and M31N-2007-11d. For the extreme luminosity of this nova, the maximum magnitude versus rate of decline relationship indicates a massive white dwarf (WD) progenitor with a low pre-outburst accretion rate. However, this prediction is in conflict with emerging theories of nova populations, which predict that luminous novae from massive WDs should preferentially exhibit an alternate spectral type (He/N) near maximum light.

  • 61. Dall'Ora, M.
    et al.
    Botticella, M. T.
    Pumo, M. L.
    Zampieri, L.
    Tomasella, L.
    Pignata, G.
    Bayless, A. J.
    Pritchard, T. A.
    Taubenberger, S.
    Kotak, R.
    Inserra, A.
    Della Valle, M.
    Cappellaro, E.
    Benetti, S.
    Benitez, S.
    Bufano, F.
    Elias-Rosa, N.
    Fraser, M.
    Haislip, J. B.
    Harutyunyan, A.
    Howell, D. A.
    Hsiao, E. Y.
    Iijima, T.
    Kankare, E.
    Kuin, P.
    Maund, J. R.
    Morales-Garoffolo, A.
    Morrell, N.
    Munari, U.
    Ochner, P.
    Pastorello, A.
    Patat, F.
    Phillips, M. M.
    Reichart, D.
    Roming, P. W. A.
    Siviero,
    Smartt, S. J.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Taddia, Francesco
    Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Valenti, S.
    Wright, D.
    THE TYPE IIP SUPERNOVA 2012aw IN M95: HYDRODYNAMICAL MODELING OF THE PHOTOSPHERIC PHASE FROM ACCURATE SPECTROPHOTOMETRIC MONITORING2014Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 787, nr 2, s. 139-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present an extensive optical and near-infrared photometric and spectroscopic campaign of the Type IIP supernova SN 2012aw. The data set densely covers the evolution of SN 2012aw shortly after the explosion through the end of the photospheric phase, with two additional photometric observations collected during the nebular phase, to fit the radioactive tail and estimate the Ni-56 mass. Also included in our analysis is the previously published Swift UV data, therefore providing a complete view of the ultraviolet-optical-infrared evolution of the photospheric phase. On the basis of our data set, we estimate all the relevant physical parameters of SN 2012aw with our radiation-hydrodynamics code: envelope mass M-env similar to 20 M-circle dot, progenitor radius R similar to 3 x 10(13) cm (similar to 430 R-circle dot), explosion energy E similar to 1.5 foe, and initial Ni-56 mass similar to 0.06 M-circle dot. These mass and radius values are reasonably well supported by independent evolutionary models of the progenitor, and may suggest a progenitor mass higher than the observational limit of 16.5 +/- 1.5 M-circle dot of the Type IIP events.

  • 62. D'Andrea, Chris B.
    et al.
    Sako, Masao
    Dilday, Benjamin
    Frieman, Joshua A.
    Holtzman, Jon
    Kessler, Richard
    Konishi, Kohki
    Schneider, D. P.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Wheeler, J. Craig
    Yasuda, Naoki
    Cinabro, David
    Jha, Saurabh
    Nichol, Robert C.
    Lampeitl, Hubert
    Smith, Mathew
    Atlee, David W.
    Bassett, Bruce
    Castander, Francisco J.
    Goobar, Ariel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Miquel, Ramon
    Nordin, Jakob
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Östman, Linda
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Prieto, José L.
    Quimby, Robert
    Riess, Adam G.
    Stritzinger, Maximilian
    Type II-P Supernovae from the SDSS-II Supernova Survey and the Standardized Candle Method2010Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 708, nr 1, s. 661-674Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We apply the Standardized Candle Method (SCM) for Type II Plateau supernovae (SNe II-P), which relates the velocity of the ejecta of a SN to its luminosity during the plateau, to 15 SNe II-P discovered over the three season run of the Sloan Digital Sky Survey-II Supernova Survey. The redshifts of these SNe—0.027 < z < 0.144—cover a range hitherto sparsely sampled in the literature; in particular, our SNe II-P sample contains nearly as many SNe in the Hubble flow (z > 0.01) as all of the current literature on the SCM combined. We find that the SDSS SNe have a very small intrinsic I-band dispersion (0.22 mag), which can be attributed to selection effects. When the SCM is applied to the combined SDSS-plus-literature set of SNe II-P, the dispersion increases to 0.29 mag, larger than the scatter for either set of SNe separately. We show that the standardization cannot be further improved by eliminating SNe with positive plateau decline rates, as proposed in Poznanski et al. We thoroughly examine all potential systematic effects and conclude that for the SCM to be useful for cosmology, the methods currently used to determine the Fe II velocity at day 50 must be improved, and spectral templates able to encompass the intrinsic variations of Type II-P SNe will be needed. Based in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

  • 63. Danilenko, A.
    et al.
    Kirichenko, A.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Shibanov, Yu.
    Zyuzin, D.
    Deep optical imaging of the gamma-ray pulsar J1048-5832 with the VLT2013Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 552, s. A127-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Context. PSR J1048-5832 is a young radio-pulsar that has recently been detected in gamma-rays with Fermi, and also in X-rays with Chandra and XMM-Newton. It powers a compact pulsar wind nebula visible in X-rays and is in many ways similar to the Vela pulsar. Aims. We present deep optical observations made with the ESO Very Large Telescope to search for optical counterparts of the pulsar and its nebula and to explore their multi-wavelength emission properties. Methods. The data were obtained in the V and R bands and were compared with archival data in other spectral domains. Results. We do not detect the pulsar in the optical and derive informative upper limits of R greater than or similar to 28(.)(m) 1 and V less than or similar to 28(.)(m) 4 for its brightness. Using a red-clump star method, we estimate an interstellar extinction towards the pulsar of A(V) approximate to 2 mag, which is consistent with the absorbing column density derived from X-rays. The respective distance agrees with the dispersion measure distance. We reanalysed the Chandra X-ray data and compared the dereddened upper limits with the unabsorbed X-ray spectrum of the pulsar. We find that regarding its optical-X-ray spectral properties this gamma-ray pulsar is not distinct from other pulsars detected in both ranges. However, like the Vela pulsar, it is very inefficient in the optical and X-rays. Among a dozen optical sources overlapping with the pulsar X-ray nebula we find one with V approximate to 26(.)(m)9 and R approximate to 26. m 3, whose colour is slightly bluer than that of the field stars and is consistent with the peculiar colours typical for pulsar nebula features. It positionally coincides with a relatively bright feature of the pulsar X-ray nebula, resembling the Crab wisp and is located in similar to 2 '' from the pulsar. We suggest this source as a counterpart candidate to the feature. Conclusions. Based on the substantial interstellar extinction towards the pulsar and its optical inefficiency, additional optical studies should be carried out at longer wavelengths.

  • 64. Das, Kaustav K.
    et al.
    Kasliwal, Mansi M.
    Fremling, Christoffer
    Yang, Sheng
    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).
    Sit, Tawny
    De, Kishalay
    Tzanidakis, Anastasios
    Perley, Daniel A.
    Anand, Shreya
    Andreoni, Igor
    Barbarino, Cristina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Brudge, K.
    Drake, Andrew
    Gal-Yam, Avishay
    Laher, Russ R.
    Karambelkar, Viraj
    Kulkarni, S. R.
    Masci, Frank J.
    Medford, Michael S.
    Polin, Abigail
    Reedy, Harrison
    Riddle, Reed
    Sharma, Yashvi
    Smith, Roger
    Yan, Lin
    Yang, Yi
    Yao, Yuhan
    Probing the Low-mass End of Core-collapse Supernovae Using a Sample of Strongly-stripped Calcium-rich Type IIb Supernovae from the Zwicky Transient Facility2023Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 959, nr 1, artikkel-id 12Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The fate of stars in the zero-age main-sequence (ZAMS) range ≈8–12 M is unclear. They could evolve to form white dwarfs or explode as electron-capture supernovae (SNe) or iron core-collapse SNe (CCSNe). Even though the initial mass function indicates that this mass range should account for over 40% of all CCSN progenitors, few have been observationally confirmed, likely due to the faintness and rapid evolution of some of these transients. In this paper, we present a sample of nine Ca-rich/O-poor Type IIb SNe detected by the Zwicky Transient Facility with progenitors likely in this mass range. These sources have a [Ca ii] λλ7291, 7324/[O i] λλ6300, 6364 flux ratio of ≳2 in their nebular spectra. Comparing the measured [O i] luminosity (≲1039 erg s−1) and derived oxygen mass (≈0.01 M) with theoretical models, we infer that the progenitor ZAMS mass for these explosions is less than 12 M. The ejecta properties (Mej ≲ 1 M and Ekin ∼ 1050 erg) are also consistent. The low ejecta mass of these sources indicates a class of strongly-stripped SNe that is a transition between the regular stripped-envelope SNe and ultra-stripped SNe. The progenitor could be stripped by a main-sequence companion and result in the formation of a neutron star−main sequence binary. Such binaries have been suggested to be progenitors of neutron star−white dwarf systems that could merge within a Hubble time and be detectable with LISA.

  • 65. Davis, Tamara M.
    et al.
    Hui, Lam
    Frieman, Joshua A.
    Haugbølle, Troels
    Kessler, Richard
    Sinclair, Benjamin
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bassett, Bruce
    Marriner, John
    Mörtsell, Edvard
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Nichol, Robert C.
    Richmond, Michael W.
    Sako, Masao
    Schneider, Donald P.
    Smith, Mathew
    The Effect of Peculiar Velocities on Supernova Cosmology2011Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 741, s. 67-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We analyze the effect that peculiar velocities have on the cosmological inferences we make using luminosity distance indicators, such as Type Ia supernovae. In particular we study the corrections required to account for (1) our own motion, (2) correlations in galaxy motions, and (3) a possible local under- or overdensity. For all of these effects we present a case study showing the impact on the cosmology derived by the Sloan Digital Sky Survey-II Supernova Survey (SDSS-II SN Survey). Correcting supernova (SN) redshifts for the cosmic microwave background (CMB) dipole slightly overcorrects nearby SNe that share some of our local motion. We show that while neglecting the CMB dipole would cause a shift in the derived equation of state of Δw ~ 0.04 (at fixed Ω m ), the additional local-motion correction is currently negligible (Δw <~ 0.01). We then demonstrate a covariance-matrix approach to statistically account for correlated peculiar velocities. This down-weights nearby SNe and effectively acts as a graduated version of the usual sharp low-redshift cut. Neglecting coherent velocities in the current sample causes a systematic shift of Δw ~ 0.02. This will therefore have to be considered carefully when future surveys aim for percent-level accuracy and we recommend our statistical approach to down-weighting peculiar velocities as a more robust option than a sharp low-redshift cut.

  • 66. Davis, Tamara
    et al.
    Mörtsell, Edvard
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Becker, A. C.
    Blondin, Stéphane
    Challis, P
    Clocchiatti, A
    Filippenko, Alexei
    Foley, Ryan
    Garnavich, P. M.
    Jha, Saurabh
    Krisciunas, K
    Kirshner, Robert
    Leibundgut, Bruno
    Li, W
    Matheson, T
    Miknaitis, G
    Pignata, G
    Rest, A
    Riess, Adam
    Schmidt, B. P.
    Smith, R. C.
    Spyromilio, J
    Stubbs, C. W.
    Suntzeff, N. B.
    Tonry, John
    Wood-Vasey, W. M.
    Zenteno, A
    Scrutinizing Exotic Cosmological Models Using ESSENCE Supernova Data Combined with Other Cosmological Probes2007Inngår i: The Astrophysical Journal, Vol. 666, nr 2, s. 716-725Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The first cosmological results from the ESSENCE supernova survey (Wood-Vasey and coworkers) are extended to a wider range of cosmological models including dynamical dark energy and nonstandard cosmological models. We fold in a greater number of external data sets such as the recent Higher-z release of high-redshift supernovae (Riess and coworkers), as well as several complementary cosmological probes. Model comparison statistics such as the Bayesian and Akaike information criteria are applied to gauge the worth of models. These statistics favor models that give a good fit with fewer parameters. Based on this analysis, the preferred cosmological model is the flat cosmological constant model, where the expansion history of the universe can be adequately described with only one free parameter describing the energy content of the universe. Among the more exotic models that provide good fits to the data, we note a preference for models whose best-fit parameters reduce them to the cosmological constant model.

  • 67. De Cia, Annalisa
    et al.
    Gal-Yam, A.
    Rubin, A.
    Leloudas, G.
    Vreeswijk, P.
    Perley, D. A.
    Quimby, R.
    Yan, Lin
    Sullivan, M.
    Flörs, A.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bersier, D.
    Cenko, S. B.
    Gal-Yam, M.
    Maguire, K.
    Ofek, E. O.
    Prentice, S.
    Schulze, S.
    Spyromilio, J.
    Valenti, S.
    Arcavi, I.
    Corsi, A.
    Howell, D. A.
    Mazzali, P.
    Kasliwal, M. M.
    Taddia, Francesco
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Yaron, O.
    Light Curves of Hydrogen-poor Superluminous Supernovae from the Palomar Transient Factory2018Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 860, nr 2, artikkel-id 100Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigate the light-curve properties of a sample of 26 spectroscopically confirmed hydrogen- poor superluminous supernovae (SLSNe-I) in the Palomar Transient Factory survey. These events are brighter than SNe Ib/c and SNe Ic-BL, on average, by about 4 and 2. mag, respectively. The peak absolute magnitudes of SLSNe-I in rest-frame g band span -22 less than or similar to M-g less than or similar to -20 mag, and these peaks are not powered by radioactive Ni-56, unless strong asymmetries are at play. The rise timescales are longer for SLSNe than for normal SNe Ib/c, by roughly 10 days, for events with similar decay times. Thus, SLSNe-I can be considered as a separate population based on photometric properties. After peak, SLSNe-I decay with a wide range of slopes, with no obvious gap between rapidly declining and slowly declining events. The latter events show more irregularities (bumps) in the light curves at all times. At late times, the SLSN-I light curves slow down and cluster around the 56Co radioactive decay rate. Powering the late-time light curves with radioactive decay would require between 1 and 10M(circle dot) of Ni masses. Alternatively, a simple magnetar model can reasonably fit the majority of SLSNe-I light curves, with four exceptions, and can mimic the radioactive decay of 56Co, up to similar to 400 days from explosion. The resulting spin values do not correlate with the host-galaxy metallicities. Finally, the analysis of our sample cannot strengthen the case for using SLSNe-I for cosmology.

  • 68. De, K.
    et al.
    Kasliwal, M. M.
    Ofek, E. O.
    Moriya, T. J.
    Burke, J.
    Cao, Y.
    Cenko, S. B.
    Doran, G. B.
    Duggan, G. E.
    Fender, R. P.
    Fransson, Claes
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Gal-Yam, A.
    Horesh, A.
    Kulkarni, S. R.
    Laher, R. R.
    Lunnan, Ragnhild
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Manulis, I.
    Masci, F.
    Mazzali, P. A.
    Nugent, P. E.
    Perley, D. A.
    Petrushevska, Tanja
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). University of Nova Gorica, Slovenia.
    Piro, A. L.
    Rumsey, C.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Sullivan, M.
    Taddia, Francesco
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    A hot and fast ultra-stripped supernova that likely formed a compact neutron star binary2018Inngår i: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 362, nr 6411, s. 201-206Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Compact neutron star binary systems are produced from binary massive stars through stellar evolution involving up to two supernova explosions. The final stages in the formation of these systems have not been directly observed. We report the discovery of iPTF 14gqr (SN 2014ft), a type Ic supernova with a fast-evolving light curve indicating an extremely low ejecta mass (approximate to 0.2 solar masses) and low kinetic energy (approximate to 2 x 10(50) ergs). Early photometry and spectroscopy reveal evidence of shock cooling of an extended helium-rich envelope, likely ejected in an intense pre-explosion mass-loss episode of the progenitor. Taken together, we interpret iPTF 14gqr as evidence for ultra-stripped supernovae that form neutron stars in compact binary systems.

  • 69. De, Kishalay
    et al.
    Kasliwal, Mansi M.
    Tzanidakis, Anastasios
    Fremling, U. Christoffer
    Adams, Scott
    Aloisi, Robert
    Andreoni, Igor
    Bagdasaryan, Ashot
    Bellm, Eric C.
    Bildsten, Lars
    Cannella, Christopher
    Cook, David O.
    Delacroix, Alexandre
    Drake, Andrew
    Duev, Dmitry
    Dugas, Alison
    Frederick, Sara
    Gal-Yam, Avishay
    Goldstein, Daniel
    Golkhou, V. Zach
    Graham, Matthew J.
    Hale, David
    Hankins, Matthew
    Helou, George
    Ho, Anna Y. Q.
    Irani, Ido
    Jencson, Jacob E.
    Kaplan, David L.
    Kaye, Stephen
    Kulkarni, S. R.
    Kupfer, Thomas
    Laher, Russ R.
    Leadbeater, Robin
    Lunnan, Ragnhild
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Masci, Frank J.
    Miller, Adam A.
    Neill, James D.
    Ofek, Eran O.
    Perley, Daniel A.
    Polin, Abigail
    Prince, Thomas A.
    Quataert, Eliot
    Reiley, Dan
    Riddle, Reed L.
    Rusholme, Ben
    Sharma, Yashvi
    Shupe, David L.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Tartaglia, Leonardo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Walters, Richard
    Yan, Lin
    Yao, Yuhan
    The Zwicky Transient Facility Census of the Local Universe. I. Systematic Search for Calcium-rich Gap Transients Reveals Three Related Spectroscopic Subclasses2020Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 905, nr 1, artikkel-id 58Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Using the Zwicky Transient Facility alert stream, we are conducting a large spectroscopic campaign to construct a complete, volume-limited sample of transients brighter than 20 mag, and coincident within 100 '' of galaxies in the Census of the Local Universe catalog. We describe the experiment design and spectroscopic completeness from the first 16 months of operations, which have classified 754 supernovae. We present results from a systematic search for calcium-rich gap transients in the sample of 22 low-luminosity (peak absolute magnitude M > -17), hydrogen-poor events found in the experiment. We report the detection of eight new events, and constrain their volumetric rate to greater than or similar to 15% +/- 5% of the SN Ia rate. Combining this sample with 10 previously known events, we find a likely continuum of spectroscopic properties ranging from events with SN Ia-like features (Ca-Ia objects) to those with SN Ib/c-like features (Ca-Ib/c objects) at peak light. Within the Ca-Ib/c events, we find two populations distinguished by their red (g - r approximate to 1.5 mag) or green (g - r approximate to 0.5 mag) colors at the r-band peak, wherein redder events show strong line blanketing features and slower light curves (similar to Ca-Ia objects), weaker He lines, and lower [Ca II]/[O I] in the nebular phase. We find that all together the spectroscopic continuum, volumetric rates, and striking old environments are consistent with the explosive burning of He shells on low-mass white dwarfs. We suggest that Ca-Ia and red Ca-Ib/c objects arise from the double detonation of He shells, while green Ca-Ib/c objects are consistent with low-efficiency burning scenarios like detonations in low-density shells or deflagrations.

  • 70. Dhawan, Suhail
    et al.
    Goobar, Ariel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Pearson Johansson, Joel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Jang, In Sung
    Rigault, Mickael
    Harvey, Luke
    Maguire, Kate
    Freedman, Wendy L.
    Madore, Barry F.
    Smith, Mathew
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kim, Young-Lo
    Andreoni, Igor
    Bellm, Eric C.
    Coughlin, Michael W.
    Dekany, Richard
    Graham, Matthew J.
    Kulkarni, Shrinivas R.
    Laher, Russ R.
    Medford, Michael S.
    Neill, James D.
    Nir, Guy
    Riddle, Reed
    Rusholme, Ben
    A Uniform Type Ia Supernova Distance Ladder with the Zwicky Transient Facility: Absolute Calibration Based on the Tip of the Red Giant Branch Method2022Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 934, nr 2, artikkel-id 185Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The current Cepheid-calibrated distance ladder measurement of H0 is reported to be in tension with the values inferred from the cosmic microwave background (CMB), assuming standard cosmology. However, some tip of the red giant branch (TRGB) estimates report H0 in better agreement with the CMB. Hence, it is critical to reduce systematic uncertainties in local measurements to understand the Hubble tension. In this paper, we propose a uniform distance ladder between the second and third rungs, combining Type Ia supernovae (SNe Ia) observed by the Zwicky Transient Facility (ZTF) with a TRGB calibration of their absolute luminosity. A large, volume-limited sample of both calibrator and Hubble flow SNe Ia from the same survey minimizes two of the largest sources of systematics: host-galaxy bias and nonuniform photometric calibration. We present results from a pilot study using the existing TRGB distance to the host galaxy of ZTF SN Ia SN 2021rhu (aka ZTF21abiuvdk) in NGC7814. Combining the ZTF calibrator with a volume-limited sample from the first data release of ZTF Hubble flow SNe Ia, we infer H0 = 76.94 ± 6.4 km s−1 Mpc−1, an 8.3% measurement. The error budget is dominated by the single object calibrating the SN Ia luminosity in this pilot study. However, the ZTF sample includes already five other SNe Ia within ∼20 Mpc for which TRGB distances can be obtained with the Hubble Space Telescope. Finally, we present the prospects of building this distance ladder out to 80 Mpc with James Webb Space Telescope observations of more than 100 ZTF SNe Ia.

  • 71.
    Dhawan, Suhail
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). University of Cambridge, UK.
    Goobar, Ariel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Smith, M.
    Johansson, Joel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Rigault, M.
    Nordin, J.
    Biswas, Rahul
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Goldstein, D.
    Nugent, P.
    Kim, Y.-L.
    Miller, A. A.
    Graham, M. J.
    Medford, M.
    Kasliwal, M. M.
    Kulkarni, S. R.
    Duev, Dmitry A.
    Bellm, E.
    Rosnet, P.
    Riddle, R.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    The Zwicky Transient Facility Type Ia supernova survey: first data release and results2022Inngår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 510, nr 2, s. 2228-2241Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Type Ia supernovae (SNe Ia) in the nearby Hubble flow are excellent distance indicators in cosmology. The Zwicky Transient Facility (ZTF) has observed a large sample of SNe from an untargeted, rolling survey, reaching 20.8, 20.6, and 20.3 mag in g r, and i band, respectively. With an FoV of 47 deg(2), ZTF discovered > 3000 SNe Ia in a little over 2.5 yr. Here, we report on the sample of 761 spectroscopically classified SNe Ia from the first year of operations (DR1). The sample has a median redshift (z) over bar = 0.057, nearly a factor of 2 higher than the current low-z sample. Our sample has a total of 934 spectra, of which 632 were obtained with the robotic SEDm on Palomar P60. We assess the potential for precision cosmology for a total of 305 SNe with redshifts from host galaxy spectra. The sample is already comparable in size to the entire combined literature low-z anchor sample. The median first detection is 13.5 d before maximum light, about 10 d earlier than the median in the literature. Furthermore, six SNe from our sample are at D-L < 80 Mpc, for which host galaxy distances can be obtained in the JAMES WEBB SPACE TELESCOPE era, such that we have calibrator and Hubble flow SNe observed with the same instrument. In the entire duration of ZTF-I, we have observed nearly 50 SNe for which we can obtain calibrator distances, key for per cent level distance scale measurements.

  • 72. Dilday, Benjamin
    et al.
    Bassett, Bruce
    Becker, Andrew
    Bender, Ralf
    Castander, Francisco
    Cinabro, David
    Frieman, Joshua A.
    Galbany, Lluís
    Garnavich, Peter
    Goobar, Ariel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hopp, Ulrich
    Ihara, Yutaka
    Jha, Saurabh W.
    Kessler, Richard
    Lampeitl, Hubert
    Marriner, John
    Miquel, Ramon
    Mollá, Mercedes
    Nichol, Robert C.
    Nordin, Jakob
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Riess, Adam G.
    Sako, Masao
    Schneider, Donald P.
    Smith, Mathew
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wheeler, J. Craig
    Östman, Linda
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Bizyaev, Dmitry
    Brewington, Howard
    Malanushenko, Elena
    Malanushenko, Viktor
    Oravetz, Dan
    Pan, Kaike
    Simmons, Audrey
    Snedden, Stephanie
    A Measurement of the Rate of Type Ia Supernovae in Galaxy Clusters from the SDSS-II Supernova Survey2010Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 715, s. 1021-1035Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present measurements of the Type Ia supernova (SN) rate in galaxy clusters based on data from the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. The cluster SN Ia rate is determined from 9 SN events in a set of 71 C4 clusters at z <= 0.17 and 27 SN events in 492 maxBCG clusters at 0.1 <= z <= 0.3. We find values for the cluster SN Ia rate of (0.37+0.17+0.01 -0.12-0.01) SNur h 2 and (0.55+0.13+0.02 -0.11-0.01) SNur h 2 (SNux = 10-12 L -1 xsun yr-1) in C4 and maxBCG clusters, respectively, where the quoted errors are statistical and systematic, respectively. The SN rate for early-type galaxies is found to be (0.31+0.18+0.01 -0.12-0.01) SNur h 2 and (0.49+0.15+0.02 -0.11-0.01) SNur h 2 in C4 and maxBCG clusters, respectively. The SN rate for the brightest cluster galaxies (BCG) is found to be (2.04+1.99+0.07 -1.11-0.04) SNur h 2 and (0.36+0.84+0.01 -0.30-0.01) SNur h 2 in C4 and maxBCG clusters, respectively. The ratio of the SN Ia rate in cluster early-type galaxies to that of the SN Ia rate in field early-type galaxies is 1.94+1.31+0.043 -0.91-0.015 and 3.02+1.31+0.062 -1.03-0.048, for C4 and maxBCG clusters, respectively. The SN rate in galaxy clusters as a function of redshift, which probes the late time SN Ia delay distribution, shows only weak dependence on redshift. Combining our current measurements with previous measurements, we fit the cluster SN Ia rate data to a linear function of redshift, and find rL = [(0.49+0.15 -0.14)+(0.91+0.85 -0.81) × z] SNuB h 2. A comparison of the radial distribution of SNe in cluster to field early-type galaxies shows possible evidence for an enhancement of the SN rate in the cores of cluster early-type galaxies. With an observation of at most three hostless, intra-cluster SNe Ia, we estimate the fraction of cluster SNe that are hostless to be (9.4+8.3 -5.1)%.

  • 73. Dilday, Benjamin
    et al.
    Smith, Mathew
    Bassett, Bruce
    Becker, Andrew
    Bender, Ralf
    Castander, Francisco
    Cinabro, David
    Filippenko, Alexei V.
    Frieman, Joshua A.
    Galbany, Lluís
    Garnavich, Peter M.
    Goobar, Ariel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Hopp, Ulrich
    Ihara, Yutaka
    Jha, Saurabh W.
    Kessler, Richard
    Lampeitl, Hubert
    Marriner, John
    Miquel, Ramon
    Mollá, Mercedes
    Nichol, Robert C.
    Nordin, Jakob
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Riess, Adam G.
    Sako, Masao
    Schneider, Donald P.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Wheeler, J. Craig
    Östman, Linda
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Bizyaev, Dmitry
    Brewington, Howard
    Malanushenko, Elena
    Malanushenko, Viktor
    Oravetz, Dan
    Pan, Kaike
    Simmons, Audrey
    Snedden, Stephanie
    Measurements of the Rate of Type Ia Supernovae at Redshift lsim0.3 from the Sloan Digital Sky Survey II Supernova Survey2010Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 713, s. 1026-1036Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a measurement of the volumetric Type Ia supernova (SN Ia) rate based on data from the Sloan Digital Sky Survey II (SDSS-II) Supernova Survey. The adopted sample of supernovae (SNe) includes 516 SNe Ia at redshift z <~ 0.3, of which 270(52%) are spectroscopically identified as SNe Ia. The remaining 246 SNe Ia were identified through their light curves; 113 of these objects have spectroscopic redshifts from spectra of their host galaxy, and 133 have photometric redshifts estimated from the SN light curves. Based on consideration of 87 spectroscopically confirmed non-Ia SNe discovered by the SDSS-II SN Survey, we estimate that 2.04+1.61 -0.95% of the photometric SNe Ia may be misidentified. The sample of SNe Ia used in this measurement represents an order of magnitude increase in the statistics for SN Ia rate measurements in the redshift range covered by the SDSS-II Supernova Survey. If we assume an SN Ia rate that is constant at low redshift (z < 0.15), then the SN observations can be used to infer a value of the SN rate of rV = (2.69+0.34+0.21 -0.30-0.01)×10-5 SNe yr-1 Mpc-3 (H 0/(70 km s-1 Mpc-1))3 at a mean redshift of ~0.12, based on 79 SNe Ia of which 72 are spectroscopically confirmed. However, the large sample of SNe Ia included in this study allows us to place constraints on the redshift dependence of the SN Ia rate based on the SDSS-II Supernova Survey data alone. Fitting a power-law model of the SN rate evolution, rV (z) = Ap × ((1 + z)/(1 + z 0))ν, over the redshift range 0.0 < z < 0.3 with z 0 = 0.21, results in Ap = (3.43+0.15 -0.15) × 10-5 SNe yr-1 Mpc-3 (H 0/(70 km s-1 Mpc-1))3 and ν = 2.04+0.90 -0.89.

  • 74. Dimitriadis, Georgios
    et al.
    Maguire, Kate
    Karambelkar, Viraj R.
    Lebron, Ryan J.
    Liu, Chang
    Kozyreva, Alexandra
    Miller, Adam A.
    Ridden-Harper, Ryan
    Anderson, Joseph P.
    Chen, Ting-Wan
    Coughlin, Michael
    Valle, Massimo Della
    Drake, Andrew
    Galbany, Lluis
    Gromadzki, Mariusz
    Groom, Steven L.
    Gutierrez, Claudia P.
    Ihanec, Nada
    Inserra, Cosimo
    Pearson Johansson, Joel
    Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Mueller-Bravo, Tomas E.
    Nicholl, Matt
    Polin, Abigail
    Rusholme, Ben
    Schulze, Steve
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Srivastav, Shubham
    Taggart, Kirsty
    Wang, Qinan
    Yang, Yi
    Young, David R.
    SN 2021zny: an early flux excess combined with late-time oxygen emission suggests a double white dwarf merger event2023Inngår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 521, nr 1, s. 1162-1183Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a photometric and spectroscopic analysis of the ultraluminous and slowly evolving 03fg-like Type Ia SN 2021zny. Our observational campaign starts from similar to 5.3 h after explosion (making SN 2021zny one of the earliest observed members of its class), with dense multiwavelength coverage from a variety of ground-and space-based telescopes, and is concluded with a nebular spectrum similar to 10 months after peak brightness. SN 2021zny displayed several characteristics of its class, such as the peak brightness (M-B = -19.95 mag), the slow decline (delta m(15)(B) = 0.62 mag), the blue early-time colours, the low ejecta velocities, and the presence of significant unburned material above the photosphere. However, a fluxexcess for the first similar to 1.5 d after explosion is observed in four photometric bands, making SN 2021zny the third 03fg-like event with this distinct behaviour, while its + 313 d spectrum shows prominent [OI] lines, a very unusual characteristic of thermonuclear SNe. The early flux excess can be explained as the outcome of the interaction of the ejecta with similar to 0 . 04 M-? of H/He-poor circumstellar material at a distance of similar to 10(12) cm, while the low ionization state of the late-time spectrum re veals lo w abundances of stable iron-peak elements. All our observations are in accordance with a progenitor system of two carbon/oxygen white dwarfs that undergo a merger event, with the disrupted white dwarf ejecting carbon-rich circumstellar material prior to the primary white dwarf detonation.

  • 75. Elíasdóttir, Á.
    et al.
    Fynbo, J. P. U.
    Hjorth, J.
    Ledoux, C.
    Watson, D. J.
    Andersen, A. C.
    Malesani, D.
    Vreeswijk, P. M.
    Prochaska, J. X.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Jaunsen, A. O.
    Dust Extinction in High-z Galaxies with Gamma-Ray Burst Afterglow Spectroscopy: The 2175 Å Feature at z = 2.452009Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 697, s. 1725-1740Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report the clear detection of the 2175 Å dust absorption feature in the optical afterglow spectrum of the gamma-ray burst (GRB) GRB 070802 at a redshift of z = 2.45. This is the highest redshift for a detected 2175 Å dust bump to date, and it is the first clear detection of the 2175 Å bump in a GRB host galaxy, while several tens of optical afterglow spectra without the bump have been recorded in the past decade. The derived extinction curve gives AV = 0.8-1.5 depending on the assumed intrinsic slope. Of the three local extinction laws, a Large Magellanic Cloud (LMC) type extinction gives the best fit to the extinction curve of the host of GRB 070802. Besides the 2175 Å bump we find that the spectrum of GRB 070802 is characterized by unusually strong low-ionization metal lines and possibly a high metallicity for a GRB sightline ([Si/H] = -0.46 ± 0.38, [Zn/H] = -0.50 ± 0.68). In particular, the spectrum of GRB 070802 is unique for a GRB spectrum in that it shows clear C I absorption features, leading us to propose a correlation between the presence of the bump and C I. The gas-to-dust ratio for the host galaxy is found to be significantly lower than that of other GRB hosts with N(H I)/AV = (2.4 ± 1.0) × 1021 cm-2 mag-1, which lies between typical Milky Way and LMC values. Our results are in agreement with the tentative conclusion reached by Gordon et al. that the shape of the extinction curve, in particular the presence of the bump, is affected by the UV flux density in the environment of the dust. Based on observations collected under progs. ID 079.D-0429(B) and 177.D-0591(P,Q), using the FORS2 instrument installed at the Cassegrain focus of the Very Large Telescope (VLT), Unit 1 - Antu, operated by the European Southern Observatory (ESO) on Cerro Paranal, Chile.

  • 76.
    Ergon, Mattias
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Jerkstrand, A.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Elias-Rosa, N.
    Fransson, Claes
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Fraser, M.
    Pastorello, A.
    Kotak, R.
    Taubenberger, S.
    Tomasella, L.
    Valenti, S.
    Benetti, S.
    Helou, G.
    Kasliwal, M. M.
    Maund, J.
    Smartt, S. J.
    Spyromilio, J.
    The Type IIb SN 2011dh: Two years of observations and modelling of the lightcurves2015Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 580, artikkel-id A142Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present optical and near-infrared (NIR) photometry and spectroscopy as well as modelling of the lightcurves of the Type IIb supernova (SN) 2011dh. Our extensive dataset, for which we present the observations obtained after day 100, spans two years, and complemented with Spitzer mid-infrared (MIR) data, we use it to build an optical-to-MIR bolometric lightcurve between days 3 and 732. To model the bolometric lightcurve before day 400 we use a grid of hydrodynamical SN models, which allows us to determine the errors in the derived quantities, and a bolometric correction determined with steady-state non-local thermodynamic equilibrium (NLTE) modelling. Using this method we find a helium core mass of 3.1+0.7-0.4 M for SN 2011dh, consistent within error bars with previous results obtained using the bolometric lightcurve before day 80. We compute bolometric and broad-band lightcurves between days 100 and 500 from spectral steady-state NLTE models, presented and discussed in a companion paper. The preferred 12 M (initial mass) model, previously found to agree well with the observed spectra, shows a good overall agreement with the observed lightcurves, although some discrepancies exist. Time-dependent NLTE modelling shows that after day ~600 a steady-state assumption is no longer valid. The radioactive energy deposition in this phase is likely dominated by the positrons emitted in the decay of 56Co, but seems insufficient to reproduce the lightcurves, and what energy source is dominating the emitted flux is unclear. We find an excess in the K and the MIR bands developing between days 100 and 250, during which an increase in the optical decline rate is also observed. A local origin of the excess is suggested by the depth of the He I 20 581 Å absorption. Steady-state NLTE models with a modest dust opacity in the core (τ = 0.44), turned on during this period, reproduce the observed behaviour, but an additional excess in the Spitzer 4.5 μm band remains. Carbon-monoxide (CO) first-overtone band emission is detected at day 206, and possibly at day 89, and assuming the additional excess to bedominated by CO fundamental band emission, we find fundamental to first-overtone band ratios considerably higher than observed in SN 1987A. The profiles of the [O I] 6300 Å and Mg I] 4571 Å lines show a remarkable similarity, suggesting that these lines originate from a common nuclear burning zone (O/Ne/Mg), and using small scale fluctuations in the line profiles we estimate a filling factor of ≲0.07 for the emitting material. This paper concludes our extensive observational and modelling work on SN 2011dh. The results from hydrodynamical modelling, steady-state NLTE modelling, and stellar evolutionary progenitor analysis are all consistent, and suggest an initial mass of ~12 M for the progenitor.

  • 77.
    Ergon, Mattias
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Lundqvist, Peter
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Fransson, Claes
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kuncarayakti, Hanindyo
    Das, Kaustav K.
    De, Kishalay
    Ferrari, Lucia
    Fremling, Christoffer
    Medler, Kyle
    Maeda, Keiichi
    Pastorello, Andrea
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Stritzinger, Maximilian D.
    Light curve and spectral modelling of the type IIb SN 2020acat. Evidence for a strong Ni bubble effect on the diffusion time2024Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 683, artikkel-id A241Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We use the light-curve and spectral synthesis code JEKYLL to calculate a set of macroscopically mixed type IIb supernova (SN) models, which are compared to both previously published and new late-phase observations of SN 2020acat. The models differ in the initial mass, in the radial mixing and expansion of the radioactive material, and in the properties of the hydrogen envelope. The best match to the photospheric and nebular spectra and light curves of SN 2020acat is found for a model with an initial mass of 17 M, strong radial mixing and expansion of the radioactive material, and a 0.1 M hydrogen envelope with a low hydrogen mass fraction of 0.27. The most interesting result is that strong expansion of the clumps containing radioactive material seems to be required to fit the observations of SN 2020acat both in the diffusion phase and in the nebular phase. These Ni bubbles are expected to expand due to heating from radioactive decays, but the degree of expansion is poorly constrained. Without strong expansion, there is a tension between the diffusion phase and the subsequent evolution, and models that fit the nebular phase produce a diffusion peak that is too broad. The diffusion-phase light curve is sensitive to the expansion of the Ni bubbles because the resulting Swiss-cheese-like geometry decreases the effective opacity and therefore the diffusion time. This effect has not been taken into account in previous light-curve modelling of stripped-envelope SNe, which may lead to a systematic underestimate of their ejecta masses. In addition to strong expansion, strong mixing of the radioactive material also seems to be required to fit the diffusion peak. It should be emphasized, however, that JEKYLL is limited to a geometry that is spherically symmetric on average, and large-scale asymmetries may also play a role. The relatively high initial mass found for the progenitor of SN 2020acat places it at the upper end of the mass distribution of type IIb SN progenitors, and a single-star origin cannot be excluded.

  • 78.
    Ergon, Mattias
    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).
    Fraser, M.
    Pastorello, A.
    Taubenberger, S.
    Elias-Rosa, N.
    Bersten, M.
    Jerkstrand, A.
    Benetti, S.
    Botticella, M. T.
    Fransson, Claes
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Harutyunyan, A.
    Kotak, R.
    Smartt, S.
    Valenti, S.
    Bufano, F.
    Cappellaro, E.
    Fiaschi, M.
    Howell, A.
    Kankare, E.
    Magill, L.
    Mattila, S.
    Maund, J.
    Naves, R.
    Ochner, P.
    Ruiz, J.
    Smith, K.
    Tomasella, L.
    Turatto, M.
    Optical and near-infrared observations of SN 2011dh-The first 100 days2014Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 562, s. A17-, artikkel-id A17Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present optical and near-infrared (NIR) photometry and spectroscopy of the Type IIb supernova (SN) 2011dh for the first 100 days. We complement our extensive dataset with Swift ultra-violet (UV) and Spitzer mid-infrared (MIR) data to build a UV to MIR bolometric lightcurve using both photometric and spectroscopic data. Hydrodynamical modelling of the SN based on this bolometric lightcurve have been presented in Bersten et al. (2012, ApJ, 757, 31). We find that the absorption minimum for the hydrogen lines is never seen below similar to 11 000 km s(-1) but approaches this value as the lines get weaker. This suggests that the interface between the helium core and hydrogen rich envelope is located near this velocity in agreement with the Bersten et al. (2012) He4R270 ejecta model. Spectral modelling of the hydrogen lines using this ejecta model supports the conclusion and we find a hydrogen mass of 0.01-0.04 M-circle dot to be consistent with the observed spectral evolution. We estimate that the photosphere reaches the helium core at 5-7 days whereas the helium lines appear between similar to 10 and similar to 15 days, close to the photosphere and then move outward in velocity until similar to 40 days. This suggests that increasing non-thermal excitation due to decreasing optical depth for the gamma-rays is driving the early evolution of these lines. The Spitzer 4.5 mu m band shows a significant flux excess, which we attribute to CO fundamental band emission or a thermal dust echo although further work using late time data is needed. The distance and in particular the extinction, where we use spectral modelling to put further constraints, is discussed in some detail as well as the sensitivity of the hydrodynamical modelling to errors in these quantities. We also provide and discuss pre- and post-explosion observations of the SN site which shows a reduction by similar to 75 percent in flux at the position of the yellow supergiant coincident with SN 2011dh. The B, V and r band decline rates of 0.0073, 0.0090 and 0.0053 mag day(-1) respectively are consistent with the remaining flux being emitted by the SN. Hence we find that the star was indeed the progenitor of SN 2011dh as previously suggested by Maund et al. (2011, ApJ, 739, L37) and which is also consistent with the results from the hydrodynamical modelling.

  • 79.
    Ergon, Mattias
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Stritzinger, Maximilian
    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).
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Fransson, Claes
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hydrodynamical modelling of Type IIb SNeInngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746Artikkel i tidsskrift (Fagfellevurdert)
  • 80. Fiore, A.
    et al.
    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.
    Jerkstrand, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Benetti, S.
    Ciolfi, R.
    Inserra, C.
    Cappellaro, E.
    Pastorello, A.
    Leloudas, G.
    Schulze, S.
    Berton, M.
    Burke, J.
    McCully, C.
    Fong, W.
    Galbany, L.
    Gromadzki, M.
    Gutiérrez, C. P.
    Hiramatsu, D.
    Hosseinzadeh, G.
    Howell, D. A.
    Kankare, E.
    Lunnan, Ragnhild
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Müller-Bravo, T. E.
    O' Neill, D.
    Nicholl, M.
    Rau, A.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Terreran, G.
    Valenti, S.
    Young, D. R.
    SN 2017gci: a nearby Type I Superluminous Supernova with a bumpy tail2021Inngår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 502, nr 2, s. 2120-2139Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present and discuss the optical spectrophotometric observations of the nearby (z = 0.087) Type I superluminous supernova (SLSN I) SN 2017gci, whose peak K-corrected absolute magnitude reaches M-g = -21.5 mag. Its photometric and spectroscopic evolution includes features of both slow- and of fast-evolving SLSN I, thus favoring a continuum distribution between the two SLSN-I subclasses. In particular, similarly to other SLSNe I, the multiband light curves (LCs) of SN 2017gci show two re-brightenings at about 103 and 142 d after the maximum light. Interestingly, this broadly agrees with a broad emission feature emerging around 6520 angstrom after similar to 51 d from the maximum light, which is followed by a sharp knee in the LC. If we interpret this feature as H alpha, this could support the fact that the bumps are the signature of late interactions of the ejecta with a (hydrogen-rich) circumstellar material. Then we fitted magnetar- and CSM-interaction-powered synthetic LCs on to the bolometric one of SN 2017gci. In the magnetar case, the fit suggests a polar magnetic field B-p similar or equal to 6 x 10(14) G, an initial period of the magnetar P-initial similar or equal to 2.8 ms, an ejecta mass M-ejecta similar or equal to 9M(circle dot) and an ejecta opacity kappa similar or equal to 0.08 cm(2) g(-1). A CSM-interaction scenario would imply a CSM mass similar or equal to 5 M-circle dot and an ejecta mass similar or equal to 12M(circle dot). Finally, the nebular spectrum of phase + 187 d was modeled, deriving a mass of similar or equal to 10 M-circle dot for the ejecta. Our models suggest that either a magnetar or CSM interaction might be the power sources for SN 2017gci and that its progenitor was a massive (40 M-circle dot) star.

  • 81. Foley, R. J.
    et al.
    Matheson, T.
    Blondin, S.
    Chornock, R.
    Silverman, J. M.
    Challis, P.
    Clocchiatti, A.
    Filippenko, A. V.
    Kirshner, R. P.
    Leibundgut, B.
    Sollerman, J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Spyromilio, J.
    Tonry, J. L.
    Davis, T. M.
    Garnavich, P. M.
    Jha, S. W.
    Krisciunas, K.
    Li, W.
    Pignata, G.
    Rest, A.
    Riess, A. G.
    Schmidt, B. P.
    Smith, R. C.
    Stubbs, C. W.
    Tucker, B. E.
    Wood-Vasey, W. M.
    Spectroscopy of High-Redshift Supernovae from the Essence Project: The First Four Years2009Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 137, s. 3731-3742Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present the results of spectroscopic observations from the ESSENCE high-redshift supernova (SN) survey during its first four years of operation. This sample includes spectra of all SNe Ia whose light curves were presented by Miknaitis et al. and used in the cosmological analyses of Davis et al. and Wood-Vasey et al. The sample represents 273 hr of spectroscopic observations with 6.5-10 m class telescopes of objects detected and selected for spectroscopy by the ESSENCE team. We present 184 spectra of 156 objects. Combining this sample with that of Matheson et al., we have a total sample of 329 spectra of 274 objects. From this, we are able to spectroscopically classify 118 Type Ia SNe. As the survey has matured, the efficiency of classifying SNe Ia has remained constant while we have observed both higher-redshift SNe Ia and SNe Ia farther from maximum brightness. Examining the subsample of SNe Ia with host-galaxy redshifts shows that redshifts derived from only the SN Ia spectra are consistent with redshifts found from host-galaxy spectra. Moreover, the phases derived from only the SN Ia spectra are consistent with those derived from light-curve fits. By comparing our spectra to local templates, we find that the rate of objects similar to the overluminous SN 1991T and the underluminous SN 1991bg in our sample are consistent with that of the local sample. We do note, however, that we detect no object spectroscopically or photometrically similar to SN 1991bg. Although systematic effects could reduce the high-redshift rate we expect based on the low-redshift surveys, it is possible that SN 1991bg-like SNe Ia are less prevalent at high redshift.

  • 82. Foley, Ryan
    et al.
    Andra, 22
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Andra, 6
    Constraining Cosmic Evolution of Type Ia Supernovae2008Inngår i: The Astrophysical Journal, Vol. 684, nr 1, s. 68-87Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a large-scale effort of creating composite spectra of high-redshift SNe Ia and comparing them to low-redshift counterparts in an attempt to understand possible cosmic evolution of SNe Ia, which has major implications for studies of dark energy. Through the ESSENCE project, we have obtained 107 spectra of 88 high-redshift SNe Ia with excellent light-curve information. In addition, we have obtained 397 spectra of low-redshift SNe Ia through a multiple-decade effort at the Lick and Keck Observatories, and we have used 45 UV spectra obtained by HST and IUE. The low-redshift spectra act as a control sample when comparing to the ESSENCE spectra. In all instances, the ESSENCE and Lick composite spectra appear very similar. The addition of galaxy light to the Lick composite spectra allows an excellent match of the overall SED with the ESSENCE composite spectra, indicating that the high-redshift SNe are more contaminated with host galaxy light than their low-redshift counterparts. This is caused by observing objects at all redshifts with similar angular slit widths, which corresponds to different projected physical distances. After correcting for the galaxy light contamination, a few marginally significant differences in the spectra remain. We have estimated the systematic errors when using current spectral templates for K-corrections to be ~0.02 mag. The variance in the composite spectra gives an estimate of the intrinsic variance in low-redshift maximum light SN spectra of ~3% relative flux in the optical and growing toward the UV. The difference between the maximum light low- and high-redshift spectra constrains the evolution of SN spectral features between our samples to be <10% relative flux in the rest-frame optical. Currently, galaxy contamination and the small samples of rest-frame UV spectra at low and high redshifts are the limiting factors for future studies.

  • 83. Foley, Ryan J.
    et al.
    Filippenko, Alexei V.
    Kessler, Richard
    Bassett, Bruce
    Frieman, Joshua A.
    Garnavich, Peter M.
    Jha, Saurabh W.
    Konishi, Kohki
    Lampeitl, Hubert
    Riess, Adam G.
    Sako, Masao
    Schneider, Donald P.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Smith, Mathew
    A MISMATCH IN THE ULTRAVIOLET SPECTRA BETWEEN LOW-REDSHIFT AND INTERMEDIATE-REDSHIFT TYPE Ia SUPERNOVAE AS A POSSIBLE SYSTEMATIC UNCERTAINTY FOR SUPERNOVA COSMOLOGY2012Inngår i: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 143, nr 5, s. 113-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present Keck high-quality rest-frame ultraviolet (UV) through optical spectra of 21 Type Ia supernovae (SNe Ia) in the redshift range 0.11 <= z <= 0.37 and a mean redshift of 0.22 that were discovered during the Sloan Digital Sky Survey-II (SDSS-II) SN Survey. Using the broadband photometry of the SDSS survey, we are able to reconstruct the SN host-galaxy spectral energy distributions (SEDs), allowing for a correction for the host-galaxy contamination in the SN Ia spectra. Comparison of composite spectra constructed from a subsample of 17 high-quality spectra to those created from a low-redshift sample with otherwise similar properties shows that the Keck/SDSS SNe Ia have, on average, extremely similar rest-frame optical spectra but show a UV flux excess. This observation is confirmed by comparing synthesized broadband colors of the individual spectra, showing a difference in mean colors at the 2.4 sigma-4.4 sigma level for various UV colors. We further see a slight difference in the UV spectral shape between SNe with low-mass and high-mass host galaxies. Additionally, we detect a relationship between the flux ratio at 2770 and 2900 angstrom and peak luminosity that differs from that observed at low redshift. We find that changing the UV SED of an SN Ia within the observed dispersion can change the inferred distance moduli by similar to 0.1 mag. This effect only occurs when the data probe the rest-frame UV. We suggest that this discrepancy could be due to differences in the host-galaxy population of the two SN samples or to small-sample statistics.

  • 84. France, Kevin
    et al.
    McCray, Richard
    Heng, Kevin
    Kirshner, Robert P.
    Challis, Peter
    Bouchet, Patrice
    Crotts, Arlin
    Dwek, Eli
    Fransson, Claes
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Garnavich, Peter M.
    Larsson, Josefin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Lawrence, Stephen S.
    Lundqvist, Peter
    Panagia, Nino
    Pun, Chun S. J.
    Smith, Nathan
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Sonneborn, George
    Stocke, John T.
    Wang, Lifan
    Wheeler, J. Craig
    Observing Supernova 1987A with the Refurbished Hubble Space Telescope2010Inngår i: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 329, nr 5999, s. 1624-1627Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Observations with the Hubble Space Telescope (HST), conducted since 1990, now offer an unprecedented glimpse into fast astrophysical shocks in the young remnant of supernova 1987A. Comparing observations taken in 2010 with the use of the refurbished instruments on HST with data taken in 2004, just before the Space Telescope Imaging Spectrograph failed, we find that the Ly alpha and H alpha lines from shock emission continue to brighten, whereas their maximum velocities continue to decrease. We observe broad, blueshifted Ly alpha, which we attribute to resonant scattering of photons emitted from hot spots on the equatorial ring. We also detect N v lambda lambda 1239, 1243 angstrom line emission, but only to the red of Ly alpha. The profiles of the N v lines differ markedly from that of H alpha, suggesting that the N4+ ions are scattered and accelerated by turbulent electromagnetic fields that isotropize the ions in the collisionless shock.

  • 85. France, Kevin
    et al.
    McCray, Richard
    Penton, Steven V.
    Kirshner, Robert P.
    Challis, Peter
    Laming, J. Martin
    Bouchet, Patrice
    Chevalier, Roger
    Garnavich, Peter M.
    Fransson, Claes
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Heng, Kevin
    Larsson, Josefin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Lawrence, Stephen
    Lundqvist, Peter
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Panagia, Nino
    Pun, Chun S. J.
    Smith, Nathan
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Sonneborn, George
    Sugerman, Ben
    Wheeler, J. Craig
    HST-COS Observations of Hydrogen, Helium, Carbon, and Nitrogen Emission from the SN 1987A Reverse Shock2011Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 743, nr 2, s. 186-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present the most sensitive ultraviolet observations of Supernova 1987A to date. Imaging spectroscopy from the Hubble Space Telescope-Cosmic Origins Spectrograph shows many narrow (Δv ~ 300 km s-1) emission lines from the circumstellar ring, broad (Δv ~ 10-20 × 103 km s-1) emission lines from the reverse shock, and ultraviolet continuum emission. The high signal-to-noise ratio (>40 per resolution element) broad Lyα emission is excited by soft X-ray and EUV heating of mostly neutral gas in the circumstellar ring and outer supernova debris. The ultraviolet continuum at λ > 1350 Å can be explained by H I two-photon (2s 2 S 1/2-1s 2 S 1/2) emission from the same region. We confirm our earlier, tentative detection of N V λ1240 emission from the reverse shock and present the first detections of broad He II λ1640, C IV λ1550, and N IV] λ1486 emission lines from the reverse shock. The helium abundance in the high-velocity material is He/H = 0.14 ± 0.06. The N V/Hα line ratio requires partial ion-electron equilibration (Te /Tp ≈ 0.14-0.35). We find that the N/C abundance ratio in the gas crossing the reverse shock is significantly higher than that in the circumstellar ring, a result that may be attributed to chemical stratification in the outer envelope of the supernova progenitor. The N/C abundance may have been stratified prior to the ring expulsion, or this result may indicate continued CNO processing in the progenitor subsequent to the expulsion of the circumstellar ring. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.