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  • 351.
    Tartaglia, Leonardo
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). INAF – Osservatorio Astronomico di Padova, Italy.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Barbarino, Cristina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Taddia, Francesco
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Mason, E.
    Berton, M.
    Taggart, K.
    Bellm, E. C.
    De, K.
    Frederick, S.
    Fremling, C.
    Gal-Yam, A.
    Golkhou, V. Z.
    Graham, M.
    Ho, A. Y. Q.
    Hung, T.
    Kaye, S.
    Kim, Y-L.
    Laher, R. R.
    Masci, F. J.
    Perley, D. A.
    Porter, M. D.
    Reiley, D. J.
    Riddle, R.
    Rusholme, B.
    Soumagnac, M. T.
    Walters, R.
    SN 2018ijp: the explosion of a stripped-envelope star within a dense H-rich shell?2021Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 650, artikkel-id A174Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, we discuss the outcomes of the follow-up campaign of SN 2018ijp, discovered as part of the Zwicky Transient Facility survey for optical transients. Its first spectrum shows similarities to broad-lined Type Ic supernovae around maximum light, whereas later spectra display strong signatures of interaction between rapidly expanding ejecta and a dense H-rich circumstellar medium, coinciding with a second peak in the photometric evolution of the transient. This evolution, along with the results of modeling of the first light-curve peak, suggests a scenario where a stripped star exploded within a dense circumstellar medium. The two main phases in the evolution of the transient could be interpreted as a first phase dominated by radioactive decays, and a later interaction-dominated phase where the ejecta collide with a pre-existing shell. We therefore discuss SN 2018jp within the context of a massive star depleted of its outer layers exploding within a dense H-rich circumstellar medium.

  • 352. Taubenberger, S.
    et al.
    Benetti, S.
    Childress, M.
    Pakmor, R.
    Hachinger, S.
    Mazzali, P. A.
    Stanishev, V.
    Elias-Rosa, N.
    Agnoletto, I.
    Bufano, F.
    Ergon, Mattias
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Harutyunyan, A.
    Inserra, C.
    Kankare, E.
    Kromer, M.
    Navasardyan, H.
    Nicolas, J.
    Pastorello, A.
    Prosperi, E.
    Salgado, F.
    Sollerman, Jesper
    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).
    Turatto, M.
    Valenti, S.
    Hillebrandt, W.
    High luminosity, slow ejecta and persistent carbon lines: SN 2009dc challenges thermonuclear explosion scenarios2011Inngår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 412, nr 4, s. 2735-2762Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Extended optical and near-IR observations reveal that SN 2009dc shares a number of similarities with normal Type Ia supernovae (SNe Ia), but is clearly overluminous, with a (pseudo-bolometric) peak luminosity of log (L) = 43.47 (erg s-1). Its light curves decline slowly over half a year after maximum light [delta m(15)(B)(true) = 0.71], and the early-time near-IR light curves show secondary maxima, although the minima between the first and the second peaks are not very pronounced. The bluer bands exhibit an enhanced fading after similar to 200 d, which might be caused by dust formation or an unexpectedly early IR catastrophe. The spectra of SN 2009dc are dominated by intermediate-mass elements and unburned material at early times, and by iron-group elements at late phases. Strong C ii lines are present until similar to 2 weeks past maximum, which is unprecedented in thermonuclear SNe. The ejecta velocities are significantly lower than in normal and even subluminous SNe Ia. No signatures of interaction with a circumstellar medium (CSM) are found in the spectra. Assuming that the light curves are powered by radioactive decay, analytic modelling suggests that SN 2009dc produced similar to 1.8 M(circle dot) of 56Ni assuming the smallest possible rise time of 22 d. Together with a derived total ejecta mass of similar to 2.8 M(circle dot), this confirms that SN 2009dc is a member of the class of possible super-Chandrasekhar-mass SNe Ia similar to SNe 2003fg, 2006gz and 2007if. A study of the hosts of SN 2009dc and other superluminous SNe Ia reveals a tendency of these SNe to explode in low-mass galaxies. A low metallicity of the progenitor may therefore be an important prerequisite for producing superluminous SNe Ia. We discuss a number of possible explosion scenarios, ranging from super-Chandrasekhar-mass white-dwarf progenitors over dynamical white-dwarf mergers and Type I<file name=mnr_18107_mu1.gif type=gif/> SNe to a core-collapse origin of the explosion. None of the models seems capable of explaining all properties of SN 2009dc, so that the true nature of this SN and its peers remains nebulous.

  • 353. Taylor, Matt
    et al.
    Cinabro, David
    Dilday, Ben
    Galbany, Lluis
    Gupta, Ravi R.
    Kessler, R.
    Marriner, John
    Nichol, Robert C.
    Richmond, Michael
    Schneider, Donald P.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    THE CORE COLLAPSE SUPERNOVA RATE FROM THE SDSS-II SUPERNOVA SURVEY2014Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 792, nr 2, s. 135-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We use the Sloan Digital Sky Survey II Supernova Survey (SDSS-II SNS) data to measure the volumetric core collapse supernova (CCSN) rate in the redshift range (0.03 < z < 0.09). Using a sample of 89 CCSN, we find a volume-averaged rate of 1.06 +/- 0.19 x 10(-4)((h/0.7)(3)/(yr Mpc(3))) at a mean redshift of 0.072 +/- 0.009. We measure the CCSN luminosity function from the data and consider the implications on the star formation history.

  • 354. Tenhu, L.
    et al.
    Larsson, J.
    Sollerman, Jesper
    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).
    Spyromilio, J.
    Lyman, J. D.
    Olofsson, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Spatial Variations and Breaks in the Optical-Near-infrared Spectra of the Pulsar and Pulsar Wind Nebula in Supernova Remnant 0540-69.32024Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 966, nr 1, artikkel-id 125Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The supernova remnant (SNR) 0540–69.3, twin of the Crab Nebula, offers an excellent opportunity to study the continuum emission from a young pulsar and pulsar wind nebula (PWN). We present observations taken with the Very Large Telescope instruments MUSE and X-shooter in the wavelength range 3000–25000 Å, which allow us to study spatial variations of the optical spectra, along with the first near-infrared (NIR) spectrum of the source. We model the optical spectra with a power law (PL) Fν ∝ να and find clear spatial variations (including a torus–jet structure) in the spectral index across the PWN. Generally, we find spectral hardening toward the outer parts, from α ∼ 1.1 to ∼0.1, which may indicate particle reacceleration by the PWN shock at the inner edge of the ejecta or alternatively time variability of the pulsar wind. The optical–NIR spectrum of the PWN is best described by a broken PL, confirming that several breaks are needed to model the full spectral energy distribution of the PWN, and suggesting the presence of more than one particle population. Finally, subtracting the PWN contribution from the pulsar spectrum we find that the spectrum is best described with a broken-PL model with a flat and a positive spectral index, in contrast to the Crab pulsar that has a negative spectral index and no break in the optical. This might imply that pulsar differences propagate to the PWN spectra.

  • 355. Terreran, G.
    et al.
    Pumo, M. L.
    Chen, T. -W.
    Moriya, T. J.
    Taddia, Fransesco
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Dessart, L.
    Zampieri, L.
    Smartt, S. J.
    Benetti, S.
    Inserra, C.
    Cappellaro, E.
    Nicholl, M.
    Fraser, M.
    Wyrzykowski, L.
    Udalski, A.
    Howell, D. A.
    McCully, C.
    Valenti, S.
    Dimitriadis, G.
    Maguire, K.
    Sullivan, M.
    Smith, K. W.
    Yaron, O.
    Young, D. R.
    Anderson, J. P.
    Della Valle, M.
    Elias-Rosa, N.
    Gal-Yam, A.
    Jerkstrand, A.
    Kankare, E.
    Pastorello, A.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Turatto, M.
    Kostrzewa-Rutkowska, Z.
    Kozlowski, S.
    Mroz, P.
    Pawlak, M.
    Pietrukowicz, P.
    Poleski, R.
    Skowron, D.
    Skowron, J.
    Soszynski, I.
    Szymanski, M. K.
    Ulaczyk, K.
    Hydrogen-rich supernovae beyond the neutrino-driven core-collapse paradigm2017Inngår i: Nature Astronomy, E-ISSN 2397-3366, Vol. 1, nr 10, s. 713-720Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Type II supernovae are the final stage of massive stars (above 8 M-circle dot) which retain part of their hydrogen-rich envelope at the moment of explosion. They typically eject up to 15 M-circle dot of material, with peak magnitudes of -17.5 mag and energies in the order of 10(51) erg, which can be explained by neutrino-driven explosions and neutron star formation. Here, we present our study of OGLE-2014-SN-073, one of the brightest type II supernovae ever discovered, with an unusually broad lightcurve combined with high ejecta velocities. From our hydrodynamical modelling, we infer a remarkable ejecta mass of 60(-16)(+42) M-circle dot and a relatively high explosion energy of 12.4(-5.9)(+13.0) x 10(51) erg. We show that this object belongs, along with a very small number of other hydrogen-rich supernovae, to an energy regime that is not explained by standard core-collapse neutrino-driven explosions. We compare the quantities inferred by the hydrodynamical modelling with the expectations of various exploding scenarios and attempt to explain the high energy and luminosity released. We find some qualitative similarities with pair-instability supernovae, although the prompt injection of energy by a magnetar seems to be a viable alternative explanation for such an extreme event.

  • 356. Thöne, Christian
    et al.
    Fynbo, Johan
    Östlin, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    andra, 11
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Spatially Resolved Properties of the GRB 060505 Host: Implications for the Nature of the Progenitor2008Inngår i: Astrophysical Journal, Vol. 676, nr 1151Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    GRB 060505 was the first well-observed nearby possible long-duration gamma-ray burst (GRB) that had no associated supernova. Here we present spatially resolved spectra of the host galaxy of GRB 060505, an Sbc spiral, at redshift z=0.0889. The GRB occurred inside a star-forming region in the northern spiral arm at 6.5 kpc from the center. From the position of the emission lines, we determine a maximum rotational velocity for the galaxy of v~212 km s-1, corresponding to a mass of 1.14×1011 Msolar within 11 kpc from the center. By fitting single-age spectral synthesis models to the stellar continuum, we derive a very young age for the GRB site, confirmed by photometric and Hα line measurements, of around ~6 Myr, which corresponds to the lifetime of a 32 Msolar star. The metallicity derived from several emission-line measurements varies throughout the galaxy and is lowest at the GRB site. Using the Two Degree Field Galaxy Redshift Survey we can locate the host galaxy in its large-scale (~Mpc) environment. The galaxy lies in the foreground of a filamentary overdensity, extending southwest from the galaxy cluster Abell 3837 at z=0.0896. The properties of the GRB site are similar to those found for other long-duration GRB host galaxies with high specific star formation rate and low metallicity, which is an indication that GRB 060505 originated from a young, massive star that died without making a supernova.

  • 357. Thöne, Christina C.
    et al.
    Michałowski, Michał J.
    Leloudas, Giorgos
    Cox, Nick L. J.
    Fynbo, Johan P. U.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Hjorth, Jens
    Vreeswijk, Paul M.
    NGC 2770: A Supernova Ib Factory?2009Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 698, nr 2, s. 1307-1320Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    NGC 2770 has been the host of three supernovae (SNe) of Type Ib during the last ten years, SN 1999eh, SN 2007uy, and SN 2008D. SN 2008D attracted special attention due to the serendipitous discovery of an associated X-ray transient. In this paper, we study the properties of NGC 2770 and specifically the three SN sites to investigate whether this galaxy is in any way peculiar to cause a high frequency of SNe Ib. We model the global spectral energy distribution of the galaxy from broadband data and derive a star formation and SN rate comparable to the values of the Milky Way. We further study the galaxy using longslit spectroscopy covering the major axis and the three SN sites. From the spectroscopic study we find subsolar metallicities for the SN sites, a high extinction and a moderate star formation rate. In a high-resolution spectrum, we also detect diffuse interstellar bands in the line of sight toward SN 2008D. A comparison of NGC 2770 to the global properties of a galaxy sample with high SN occurrence (>= 3 SN in the last 100 years) suggests that NGC 2770 is not particularly destined to produce such an enhancement of observed SNe. Its properties are also very different from gamma-ray burst host galaxies. Statistical considerations on SN Ib detection rates give a probability of ~1.5% to find a galaxy with three Ib SNe detected in ten years. The high number of rare Ib SNe in this galaxy is therefore likely to be a coincidence rather than special properties of the galaxy itself. NGC 2770 has a small irregular companion, NGC 2770B, which is highly star-forming, has a very low mass and one of the lowest metallicities detected in the nearby universe as derived from longslit spectroscopy. In the most metal poor part, we even detect Wolf-Rayet (WR) features, which is at odds with most current models of WR stars which require high metallicities. Based on observations with the Nordic Optical Telescope, ESO proposal 080.D-0526, the GALEX and NED databases.

  • 358. Tinyanont, Samaporn
    et al.
    Woosley, Stan E.
    Taggart, Kirsty
    Foley, Ryan J.
    Yan, Lin
    Lunnan, Ragnhild
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Davis, Kyle W.
    Kilpatrick, Charles D.
    Siebert, Matthew R.
    Schulze, Steve
    Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Ashall, Chris
    Chen, Ting-Wan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    De, Kishalay
    Dimitriadis, Georgios
    Dong, Dillon Z.
    Fremling, Christoffer
    Gagliano, Alexander
    Jha, Saurabh W.
    Jones, David O.
    Kasliwal, Mansi M.
    Miao, Hao-Yu
    Pan, Yen-Chen
    Perley, Daniel A.
    Ravi, Vikram
    Rojas-Bravo, César
    Sfaradi, Itai
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Alarcon, Vanessa
    Angulo, Rodrigo
    Clever, Karoli E.
    Crawford, Payton
    Couch, Cirilla
    Dandu, Srujan
    Dhara, Atirath
    Johnson, Jessica
    Lai, Zhisen
    Smith, Carli
    Supernova 2020wnt: An Atypical Superluminous Supernova with a Hidden Central Engine2023Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 951, nr 1, artikkel-id 34Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present observations of a peculiar hydrogen- and helium-poor stripped-envelope (SE) supernova (SN) 2020wnt, primarily in the optical and near-infrared (near-IR). Its peak absolute bolometric magnitude of −20.9 mag (Lbol, peak = (6.8 ± 0.3) × 1043 erg s−1) and a rise time of 69 days are reminiscent of hydrogen-poor superluminous SNe (SLSNe I), luminous transients potentially powered by spinning-down magnetars. Before the main peak, there is a brief peak lasting <10 days post explosion, likely caused by interaction with circumstellar medium (CSM) ejected ∼years before the SN explosion. The optical spectra near peak lack a hot continuum and O ii absorptions, which are signs of heating from a central engine; they quantitatively resemble those of radioactivity-powered hydrogen/helium-poor Type Ic SESNe. At ∼1 yr after peak, nebular spectra reveal a blue pseudo-continuum and narrow O i recombination lines associated with magnetar heating. Radio observations rule out strong CSM interactions as the dominant energy source at +266 days post peak. Near-IR observations at +200–300 days reveal carbon monoxide and dust formation, which causes a dramatic optical light-curve dip. Pair-instability explosion models predict slow light curve and spectral features incompatible with observations. SN 2020wnt is best explained as a magnetar-powered core-collapse explosion of a 28 M pre-SN star. The explosion kinetic energy is significantly larger than the magnetar energy at peak, effectively concealing the magnetar-heated inner ejecta until well after peak. SN 2020wnt falls into a continuum between normal SNe Ic and SLSNe I, and demonstrates that optical spectra at peak alone cannot rule out the presence of a central engine.

  • 359. Tomasella, L.
    et al.
    Cappellaro, E.
    Fraser, M.
    Pumo, M. L.
    Pastorello, A.
    Pignata, G.
    Benetti, S.
    Bufano, F.
    Dennefeld, M.
    Harutyunyan, A.
    Iijima, T.
    Jerkstrand, A.
    Kankare, E.
    Kotak, R.
    Magill, L.
    Nascimbeni, V.
    Ochner, P.
    Siviero, A.
    Smartt, S.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Stanishev, V.
    Taddia, F.
    Taubenberger, S.
    Turatto, M.
    Valenti, S.
    Wright, D. E.
    Zampieri, L.
    Comparison of progenitor mass estimates for the Type IIP SN 2012A2013Inngår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 434, nr 2, s. 1636-1657Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present the one-year long observing campaign of SN 2012A which exploded in the nearby (9.8 Mpc) irregular galaxy NGC 3239. The photometric evolution is that of a normal Type IIP supernova, but the plateau is shorter and the luminosity not as constant as in other supernovae of this type. The absolute maximum magnitude, with M-B = -16.23 +/- 0.16 mag, is close to the average for SN IIP. Thanks also to the strong UV flux in the early phase, SN 2012A reached a peak luminosity of about 2 x 10(42) erg s(-1), which is brighter than those of other SNe with a similar Ni-56 mass. The latter was estimated from the luminosity in the exponential tail of the light curve and found to be M(Ni-56) = 0.011 +/- 0.004 M-circle dot, which is intermediate between standard and faint SN IIP. The spectral evolution of SN 2012A is also typical of SN IIP, from the early spectra dominated by a blue continuum and very broad (similar to 10(4) km s(-1)) Balmer lines, to the late-photospheric spectra characterized by prominent P-Cygni features of metal lines (Fe ii, Sc ii, Ba ii, Ti ii, Ca ii, Na i D). The photospheric velocity is moderately low, similar to 3 x 10(3) km s(-1) at 50 d, for the low optical depth metal lines. The nebular spectrum obtained 394 d after the shock breakout shows the typical features of SNe IIP and the strength of the [O i] doublet suggests a progenitor of intermediate mass, similar to SN 2004et (similar to 15 M-circle dot). A candidate progenitor for SN 2012A has been identified in deep, pre-explosion K-'-band Gemini North Near-InfraRed Imager and Spectrometer images, and found to be consistent with a star with a bolometric magnitude -7.08 +/- 0.36 (log L/L-circle dot = 4.73 +/- 0.14 dex). The magnitude of the recovered progenitor in archival images points towards a moderate-mass 10.5(-2)(+4.5) M-circle dot star as the precursor of SN 2012A. The explosion parameters and progenitor mass were also estimated by means of a hydrodynamical model, fitting the bolometric light curve, the velocity and the temperature evolution. We found a best fit for a kinetic energy of 0.48 foe, an initial radius of 1.8 x 10(13) cm and ejecta mass of 12.5 M-circle dot. Even including the mass for the compact remnant, this appears fully consistent with the direct measurements given above.

  • 360.
    Tsaprazi, Eleni
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Jasche, Jens
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Goobar, Ariel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Peiris, Hiranya
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). University College London, UK.
    Andreoni, Igor
    Coughlin, Michael W.
    Fremling, Christoffer U.
    Graham, Matthew J.
    Kasliwal, Mansi
    Kulkarni, Shri R.
    Mahabal, Ashish A.
    Riddle, Reed
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Tzanidakis, Anastasios
    The large-scale environment of thermonuclear and core-collapse supernovae2022Inngår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 510, nr 1, s. 366-372Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The new generation of wide-field time-domain surveys has made it feasible to study the clustering of supernova (SN) host galaxies in the large-scale structure (LSS) for the first time. We investigate the LSS environment of SN populations, using 106 dark matter density realisations with a resolution of ∼3.8 Mpc, constrained by the 2M+ + galaxy survey. We limit our analysis to redshift z < 0.036, using samples of 498 thermonuclear and 782 core-collapse SNe from the Zwicky Transient Facility’s Bright Transient Survey and Census of the Local Universe catalogues. We detect clustering of SNe with high significance; the observed clustering of the two SNe populations is consistent with each other. Further, the clustering of SN hosts is consistent with that of the Sloan Digital Sky Survey (SDSS) Baryon Oscillation Spectroscopic Survey DR12 spectroscopic galaxy sample in the same redshift range. Using a tidal shear classifier, we classify the LSS into voids, sheets, filaments, and knots. We find that both SNe and SDSS galaxies are predominantly found in sheets and filaments. SNe are significantly under-represented in voids and over-represented in knots compared to the volume fraction in these structures. This work opens the potential for using forthcoming wide-field deep SN surveys as a complementary LSS probe.

  • 361.
    Tziamtzis, Anestis
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Schirmer, M.
    Lundqvist, Peter
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Observational and theoretical constraints for an Hα-halo around the Crab nebula2009Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 497, nr 1, s. 167-176Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aims: We searched for a fast moving Hα shell around the Crab nebula. Such a shell could account for this supernova remnant's missing mass, and carry enough kinetic energy to make SN 1054 a normal type II event. Methods: Deep Hα images were obtained with WFI at the 2.2 m MPG/ESO telescope and with MOSCA at the 2.56 m NOT. The data are compared with theoretical expectations derived from shell models with ballistic gas motion, constant temperature, constant degree of ionisation, and a power law for the density profile. Results: We reach a surface brightness limit of 5 × 10-8 erg s-1 cm-2 sr-1. A halo is detected, but at a much higher surface brightness than our models of recombination emission and dust scattering predict. Only collisional excitation of Lyβ with partial de-excitation to Hα could explain such amplitudes. We show that the halo seen is caused by PSF scattering and thus not related to a real shell. We also investigated the feasibility of a spectroscopic detection of high-velocity Hα gas towards the centre of the Crab nebula. Modelling the emission spectra shows that such gas easily evades detection in the complex spectral environment of the Hα-line. Conclusions: PSF scattering significantly contaminates our data, preventing a detection of the predicted fast shell. A real halo with observed peak flux of about 2 × 10-7 erg s-1 cm-2 sr-1 could still be accomodated within our error bars, but our models predict a factor 4 lower surface brightness. Eight meters class telescopes could detect such fluxes unambiguously, provided that a sufficiently accurate PSF model is available. Finally, we note that PSF scattering also affects other research areas where faint haloes are searched for around bright and extended targets. Based on observations made with ESO Telescopes at the La Silla and Paranal Observatories, Chile (ESO Programmes 66.D-0489, 68.D-0096 and 170.A-0519). Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.

  • 362. Valenti, S.
    et al.
    Fraser, M.
    Benetti, S.
    Pignata, G.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Inserra, C.
    Cappellaro, E.
    Pastorello, A.
    Smartt, S. J.
    Ergon, Mattias
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Botticella, M. T.
    Brimacombe, J.
    Bufano, F.
    Crockett, M.
    Eder, I.
    Fugazza, D.
    Haislip, J. B.
    Hamuy, M.
    Harutyunyan, A.
    Ivarsen, K. M.
    Kankare, E.
    Kotak, R.
    LaCluyze, A. P.
    Magill, L.
    SUBMattila, S.
    Maza, J.
    Mazzali, P. A.
    Reichart, D. E.
    Taubenberger, S.
    Turatto, M.
    Zampieri, L.
    SN 2009jf: a slow-evolving stripped-envelope core-collapse supernova2011Inngår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 416, nr 4, s. 3138-3159Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present an extensive set of photometric and spectroscopic data for SN 2009jf, a nearby Type Ib supernova (SN), spanning from similar to 20 d before B-band maximum to 1 yr after maximum. We show that SN 2009jf is a slowly evolving and energetic stripped-envelope SN and is likely from a massive progenitor (25-30 M(circle dot)). The large progenitor's mass allows us to explain the complete hydrogen plus helium stripping without invoking the presence of a binary companion. The SN occurred close to a young cluster, in a crowded environment with ongoing star formation. The spectroscopic similarity with the He-poor Type Ic SN 2007gr suggests a common progenitor for some SNe Ib and Ic. The nebular spectra of SN 2009jf are consistent with an asymmetric explosion, with an off-centre dense core. We also find evidence that Herich Ib SNe have a rise time longer than other stripped-envelope SNe, however confirmation of this result and further observations are needed.

  • 363. Valenti, S.
    et al.
    Pastorello, A.
    Benitez-Herrera, S.
    Taubenberger, S.
    Smartt, S. J.
    Sullivan, M.
    Benetti, S.
    Cappellaro, E.
    Greggio, L.
    Hachinger, S.
    Turatto, M.
    Zampieri, L.
    Baltay, C.
    Ellman, N.
    Hadjiyska, E.
    McKinnon, R.
    Rabinowitz, D.
    Nugent, P.
    Mazzali, P. A.
    Maguire, K.
    Pan, Yen-Chen
    Hook, I.
    Fraser, M.
    Inserra, C.
    Magill, L.
    Maund, J.
    McCrum, M.
    Kotak, R.
    Smith, K. W.
    Young, D. R.
    Chen, T.-W.
    Wright, D.
    Scalzo, R.
    Schmidt, B. P.
    Sim, S. A.
    Yuan, F.
    Stanishev, V.
    Patat, N.
    Botticella, M. T.
    Dall'Ora, M.
    Limongi, M.
    Pumo, M. L.
    Dennefeld, M.
    Blagorodnova, N.
    Elias-Rosa, N.
    Walton, N. A.
    Cellier-Holzem, F.
    Bongard, S.
    Regnault, N.
    Pain, R.
    Guillou, L. Le
    Hillebrandt, W.
    Kromer, M.
    Sternberg, A.
    Bufano, F.
    Pignata, G.
    Anderson, J. P.
    Hamuy, M.
    Clocchiatti, A.
    Eldridge, J. J.
    Feindt, U.
    Kowalski, M.
    Kankare, E.
    Mattila, S.
    Walker, E. S.
    Amanullah, Rahman
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Fransson, Claes
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Goobar, Ariel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Ergon, M.
    Gal-Yam, A.
    Yaron, O.
    PESSTO spectroscopic classification of La Silla-Quest Transients2012Rapport (Annet vitenskapelig)
    Abstract [en]

    PESSTO is the "Public ESO Spectroscopic Survey of Transient Objects" (http://www.pessto.org) using the ESO New Technology Telescope (NTT) at La Silla and the EFOSC2 (optical) and SOFI (near-IR) spectrographs. It is one of two currently running public spectroscopic surveys at ESO. The survey details are as follows: - PESSTO has 90 nights per year on the NTT: 9 lunations (August to April), 10 nights per lunation (we are not observing May-July).

  • 364. Valenti, Stefano
    et al.
    Taubenberger, Stefan
    Pastorello, Andrea
    Aramyan, Levon
    Botticella, Maria Teresa
    Fraser, Morgan
    Benetti, Stefano
    Smartt, Stephen J.
    Cappellaro, Enrico
    Elias-Rosa, Nancy
    Ergon, Mattias
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Magill, Lindsay
    Magnier, Eugene
    Kotak, Rubina
    Price, Paul A.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Tomasella, Lina
    Turatto, Massimo
    Wright, Darryl E.
    A SPECTROSCOPICALLY NORMAL TYPE Ic SUPERNOVA FROM A VERY MASSIVE PROGENITOR2012Inngår i: The Astrophysical Journal Letters, ISSN 2041-8205, Vol. 749, nr 2, s. L28-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present observations of the Type Ic supernova (SN Ic) 2011bm spanning a period of about one year. The data establish that SN 2011bm is a spectroscopically normal SN Ic with moderately low ejecta velocities and with a very slow spectroscopic and photometric evolution (more than twice as slow as SN 1998bw). The Pan-STARRS1 retrospective detection shows that the rise time from explosion to peak was similar to 40 days in the R band. Through an analysis of the light curve and the spectral sequence, we estimate a kinetic energy of similar to 7-17 foe and a total ejected mass of similar to 7-17 M-circle dot, 5-10 M-circle dot of which is oxygen and 0.6-0.7 M-circle dot is Ni-56. The physical parameters obtained for SN 2011bm suggest that its progenitor was a massive star of initial mass 30-50 M-circle dot. The profile of the forbidden oxygen lines in the nebular spectra shows no evidence of a bi-polar geometry in the ejected material.

  • 365. van Velzen, Sjoert
    et al.
    Gezari, Suvi
    Hammerstein, Erica
    Roth, Nathaniel
    Frederick, Sara
    Ward, Charlotte
    Hung, Tiara
    Cenko, S. Bradley
    Stein, Robert
    Perley, Daniel A.
    Taggart, Kirsty
    Foley, Ryan J.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Blagorodnova, Nadejda
    Andreoni, Igor
    Bellm, Eric C.
    Brinnel, Valery
    De, Kishalay
    Dekany, Richard
    Feeney, Michael
    Fremling, Christoffer
    Giomi, Matteo
    Golkhou, V. Zach
    Graham, Matthew J.
    Ho, Anna. Y. Q.
    Kasliwal, Mansi M.
    Kilpatrick, Charles D.
    Kulkarni, Shrinivas R.
    Kupfer, Thomas
    Laher, Russ R.
    Mahabal, Ashish
    Masci, Frank J.
    Miller, Adam A.
    Nordin, Jakob
    Riddle, Reed
    Rusholme, Ben
    Santen, Jakob van
    Sharma, Yashvi
    Shupe, David L.
    Soumagnac, Maayane T.
    Seventeen Tidal Disruption Events from the First Half of ZTF Survey Observations: Entering a New Era of Population Studies2021Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 908, nr 1, artikkel-id 4Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    While tidal disruption events (TDEs) have long been heralded as laboratories for the study of quiescent black holes, the small number of known TDEs and uncertainties in their emission mechanism have hindered progress toward this promise. Here we present 17 new TDEs that have been detected recently by the Zwicky Transient Facility along with Swift UV and X-ray follow-up observations. Our homogeneous analysis of the optical/UV light curves, including 22 previously known TDEs from the literature, reveals a clean separation of light-curve properties with spectroscopic class. The TDEs with Bowen fluorescence features in their optical spectra have smaller blackbody radii, lower optical luminosities, and higher disruption rates compared to the rest of the sample. The small subset of TDEs that show only helium emission lines in their spectra have the longest rise times, the highest luminosities, and the lowest rates. A high detection rate of Bowen lines in TDEs with small photometric radii could be explained by the high density that is required for this fluorescence mechanism. The stellar debris can provide a source for this dense material. Diffusion of photons through this debris may explain why the rise and fade timescale of the TDEs in our sample are not correlated. We also report, for the first time, the detection of soft X-ray flares from a TDE on similar to day timescales. Based on the fact that the X-ray flares peak at a luminosity similar to the optical/UV blackbody luminosity, we attribute them to brief glimpses through a reprocessing layer that otherwise obscures the inner accretion flow.

  • 366. van Velzen, Sjoert
    et al.
    Gezaril, Suvi
    Cenko, S. Bradley
    Karal, Erin
    Miller-Jones, James C. A.
    Hung, Tiara
    Bright, Joe
    Roth, Nathaniel
    Blagorodnova, Nadejda
    Huppenkothen, Daniela
    Yan, Lin
    Ofek, Eran
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Frederic, Sara
    Ward, Harlotte
    Grahan, Matthew J.
    Fender, Rob
    Kasliwal, Mansi M.
    Canella, Chris
    Stein, Robert
    Giomi, Matteo
    Brinnel, Valery
    van Santen, Jakob
    Nordin, Jakob
    Bellm, Eric C.
    Dekany, Richard
    Fremling, Christoffer
    Golkhou, V. Zach
    Kupfer, Thomas
    Kulkarni, Shrinivas R.
    Laher, Russ R.
    Mahabal, Ashish
    Masci, Frank J.
    Miller, Adam A.
    Neill, James D.
    Riddle, Reed
    Rigault, Mickael
    Rusholme, Ben
    Soumagnac, Maayane T.
    Tachiba, Yutaro
    The First Tidal Disruption Flare in ZTF: From Photometric Selection to Multi-wavelength Characterization2019Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 872, nr 2, artikkel-id 198Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present Zwicky Transient Facility (ZTF) observations of the tidal disruption flare AT2018zr/PS18kh reported by Holoien et al. and detected during ZTF commissioning. The ZTF light curve of the tidal disruption event (TDE) samples the rise-to-peak exceptionally well, with 50. days of g- and r-band detections before the time of maximum light. We also present our multi-wavelength follow-up observations, including the detection of a thermal (kT approximate to 100 eV) X-ray source that is two orders of magnitude fainter than the contemporaneous optical/UV blackbody luminosity, and a stringent upper limit to the radio emission. We use observations of 128 known active galactic nuclei (AGNs) to assess the quality of the ZTF astrometry, finding a median host-flare distance of 0.'' 2 for genuine nuclear flares. Using ZTF observations of variability from known AGNs and supernovae we show how these sources can be separated from TDEs. A combination of light-curve shape, color, and location in the host galaxy can be used to select a clean TDE sample from multi-band optical surveys such as ZTF or the Large Synoptic Survey Telescope.

  • 367. van Velzen, Sjoert
    et al.
    Stein, Robert
    Gilfanov, Marat
    Kowalski, Marek
    Hayasaki, Kimitake
    Reusch, Simeon
    Yao, Yuhan
    Garrappa, Simone
    Franckowiak, Anna
    Gezari, Suvi
    Nordin, Jakob
    Fremling, Christoffer
    Sharma, Yashvi
    Yan, Lin
    Kool, Erik C.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Stern, Daniel
    Veres, Patrik M.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Medvedev, Pavel
    Sunyaev, Rashid
    Bellm, Eric C.
    Dekany, Richard G.
    Duev, Dimitri A.
    Graham, Matthew J.
    Kasliwal, Mansi M.
    Kulkarni, Shrinivas R.
    Laher, Russ R.
    Riddle, Reed L.
    Rusholme, Ben
    Establishing accretion flares from supermassive black holes as a source of high-energy neutrinos2024Inngår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 529, nr 3, s. 2559-2576Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The origin of cosmic high-energy neutrinos remains largely unexplained. For high-energy neutrino alerts from IceCube, a coincidence with time-variable emission has been seen for three different types of accreting black holes: (1) a gamma-ray flare from a blazar (TXS 0506+056), (2) an optical transient following a stellar tidal disruption event (TDE; AT2019dsg), and (3) an optical outburst from an active galactic nucleus (AGN; AT2019fdr). For the latter two sources, infrared follow-up observations revealed a powerful reverberation signal due to dust heated by the flare. This discovery motivates a systematic study of neutrino emission from all supermassive black hole with similar dust echoes. Because dust reprocessing is agnostic to the origin of the outburst, our work unifies TDEs and high-amplitude flares from AGN into a population that we dub accretion flares. Besides the two known events, we uncover a third flare that is coincident with a PeV-scale neutrino (AT2019aalc). Based solely on the optical and infrared properties, we estimate a significance of 3.6σ for this association of high-energy neutrinos with three accretion flares. Our results imply that at least ∼10 per cent of the IceCube high-energy neutrino alerts could be due to accretion flares. This is surprising because the sum of the fluence of these flares is at least three orders of magnitude lower compared to the total fluence of normal AGN. It thus appears that the efficiency of high-energy neutrino production in accretion flares is increased compared to non-flaring AGN. We speculate that this can be explained by the high Eddington ratio of the flares.

  • 368. Vergani, S. D.
    et al.
    Flores, H.
    Covino, S.
    Fugazza, D.
    Gorosabel, J.
    Levan, A. J.
    Puech, M.
    Salvaterra, R.
    Tello, J. C.
    de Ugarte Postigo, A.
    D'Avanzo, P.
    D'Elia, V.
    Fernández, M.
    Fynbo, J. P. U.
    Ghirlanda, G.
    Jelínek, M.
    Lundgren, A.
    Malesani, D.
    Palazzi, E.
    Piranomonte, S.
    Rodrigues, M.
    Sánchez-Ramírez, R.
    Terrón, V.
    Thöne, C. C.
    Antonelli, L. A.
    Campana, S.
    Castro-Tirado, A. J.
    Goldoni, P.
    Hammer, F.
    Hjorth, J.
    Jakobsson, P.
    Kaper, L.
    Melandri, A.
    Milvang-Jensen, B.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Tagliaferri, G.
    Tanvir, N. R.
    Wiersema, K.
    Wijers, R. A. M. J.
    GRB 091127/SN 2009nz and the VLT/X-shooter spectroscopy of its host galaxy: probing the faint end of the mass-metallicity relation2011Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 535, s. A127-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We perform a detailed study of the gamma-ray burst GRB 091127/SN 2009nz host galaxy at z = 0.490 using the VLT/X-shooter spectrograph in slit and integral-field unit (IFU) mode. From the analysis of the optical and X-ray afterglow data obtained from ground-based telescopes and Swift-XRT, we confirm the presence of a bump associated with SN 2009nz and find evidence of a possible jet break in the afterglow lightcurve. The X-shooter afterglow spectra reveal several emission lines from the underlying host, from which we derive its integrated properties. These properties agree with those of previously studied GRB-SN hosts and, more generally, with those of the long GRB host population. We use the Hubble Space Telescope and ground-based images of the host to determine its stellar mass (M⋆). Our results extend to lower M⋆ values the M-Z plot derived for the sample of long GRB hosts at 0.3 < z < 1.0 adding new information to probe the faint end of the M-Z relation and the shift of the LGRB host M-Z relation from that found from emission-line galaxy surveys. Thanks to the IFU spectroscopy, we can build the two-dimensional (2D) velocity, velocity dispersion, and star formation rate (SFR) maps. They show that the host galaxy has perturbed rotation kinematics with evidence of a SFR enhancement consistent with the afterglow position. Based on observations made with ESO Telescopes at Paranal Observatory under programmes ID 084.A-0260 and 086.A-0874.

  • 369. Villarroel, Beatriz
    et al.
    Nyholm, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Karlsson, Torgny
    Comerón, Sébastien
    Korn, Andreas J.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Zackrisson, Erik
    AGN Luminosity and Stellar Age: Two Missing Ingredients for AGN Unification as Seen with iPTF Supernovae2017Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 837, nr 2, artikkel-id 110Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Active galactic nuclei (AGNs) are extremely powerful cosmic objects, driven by accretion of hot gas upon super-massive black holes. The zoo of AGN classes is divided into two major groups, with Type-1 AGNs displaying broad Balmer emission lines and Type-2 narrow ones. For a long time it was believed that a Type-2 AGN is a Type-1 AGN viewed through a dusty kiloparsec-sized torus, but an emerging body of observations suggests more than just the viewing angle matters. Here we report significant differences in supernova (SN) counts and classes in the first study to date of SNe near Type-1 and Type-2 AGN host galaxies, using data from the intermediate Palomar Transient Factory, the Sloan Digital Sky Survey Data Release 7, and Galaxy Zoo. We detect many more SNe in Type-2 AGN hosts (size of effect similar to 5.1 sigma) compared to Type-1 hosts, which shows that the two classes of AGN are located inside host galaxies with different properties. In addition, Type-1 and Type-2 AGNs that are dominated by star formation according to Wide-field Infrared Survey Explorer colors m(W1) - m(W2) < 0.5 and are matched in 22 mu m absolute magnitude differ by a factor of ten in L[O III] lambda 5007 luminosity, suggesting that when residing in similar types of host galaxies Type-1 AGNs are much more luminous. Our results demonstrate two more factors that play an important role in completing the current picture: the age of stellar populations and the AGN luminosity. This has immediate consequences for understanding the many AGN classes and galaxy evolution.

  • 370. Vreeswijk, Paul M.
    et al.
    Leloudas, Giorgos
    Gal-Yam, Avishay
    De Cia, Annalisa
    Perley, Daniel A.
    Quimby, Robert M.
    Waldman, Roni
    Sullivan, Mark
    Yan, Lin
    Ofek, Eran O.
    Fremling, Christoffer
    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).
    Valenti, Stefano
    Arcavi, Iair
    Howell, D. Andrew
    Filippenko, Alexei V.
    Cenko, S. Bradley
    Yaron, Ofer
    Kasliwal, Mansi M.
    Cao, Yi
    Ben-Ami, Sagi
    Horesh, Assaf
    Rubin, Adam
    Lunnan, Ragnhild
    Nugent, Peter E.
    Laher, Russ
    Rebbapragada, Umaa D.
    Wozniak, Przemyslaw
    Kulkarni, Shrinivas R.
    ON THE EARLY-TIME EXCESS EMISSION IN HYDROGEN-POOR SUPERLUMINOUS SUPERNOVAE2017Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 835, nr 1, artikkel-id 58Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present the light curves of the hydrogen-poor superluminous supernovae (SLSNe I) PTF 12dam and iPTF 13dcc, discovered by the (intermediate) Palomar Transient Factory. Both show excess emission at early times and a slowly declining light curve at late times. The early bump in PTF 12dam is very similar in duration (similar to 10 days) and brightness relative to the main peak (2-3 mag fainter) compared to that observed in other SLSNe I. In contrast, the long-duration (>30 days) early excess emission in iPTF 13dcc, whose brightness competes with that of the main peak, appears to be of a different nature. We construct bolometric light curves for both targets, and fit a variety of light-curve models to both the early bump and main peak in an attempt to understand the nature of these explosions. Even though the slope of the late-time decline in the light curves of both SLSNe is suggestively close to that expected from the radioactive decay of Ni-56 and Co-56, the amount of nickel required to power the full light curves is too large considering the estimated ejecta mass. The magnetar model including an increasing escape fraction provides a reasonable description of the PTF 12dam observations. However, neither the basic nor the double-peaked magnetar model is capable of reproducing the light curve of iPTF 13dcc. A model combining a shock breakout in an extended envelope with late-time magnetar energy injection provides a reasonable fit to the iPTF 13dcc observations. Finally, we find that the light curves of both PTF 12dam and iPTF 13dcc can be adequately fit with the model involving interaction with the circumstellar medium.

  • 371. Vreeswijk, Paul M.
    et al.
    Savaglio, Sandra
    Gal-Yam, Avishay
    De Cia, Annalisa
    Quimby, Robert M.
    Sullivan, Mark
    Cenko, S. Bradley
    Perley, Daniel A.
    Filippenko, Alexei V.
    Clubb, Kelsey I.
    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).
    Leloudas, Giorgos
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). University of Copenhagen, Denmark.
    Arcavi, Iair
    Rubin, Adam
    Kasliwal, Mansi M.
    Cao, Yi
    Yaron, Ofer
    Tal, David
    Ofek, Eran O.
    Capone, John
    Kutyrev, Alexander S.
    Toy, Vicki
    Nugent, Peter E.
    Laher, Russ
    Surace, Jason
    Kulkarni, Shrinivas R.
    THE HYDROGEN-POOR SUPERLUMINOUS SUPERNOVA iPTF 13ajg AND ITS HOST GALAXY IN ABSORPTION AND EMISSION2014Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 797, nr 1, s. 24-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present imaging and spectroscopy of a hydrogen-poor superluminous supernova (SLSN) discovered by the intermediate Palomar Transient Factory, iPTF 13ajg. At a redshift of z = 0.7403, derived from narrow absorption lines, iPTF 13ajg peaked at an absolute magnitude of M-u,M-AB = -22.5, one of the most luminous supernovae to date. The observed bolometric peak luminosity of iPTF 13ajg is 3.2 x 10(44) erg s(-1), while the estimated total radiated energy is 1.3 x 10(51) erg. We detect narrow absorption lines of Mg I, Mg II, and Fe II, associated with the cold interstellar medium in the host galaxy, at two different epochs with X-shooter at the Very Large Telescope. From Voigt profile fitting, we derive the column densities log N(Mg I) = 11.94 +/- 0.06, log N(Mg II) = 14.7 +/- 0.3, and log N(Fe II) = 14.25 +/- 0.10. These column densities, as well as the Mg I and Mg II equivalent widths of a sample of hydrogen-poor SLSNe taken from the literature, are at the low end of those derived for gamma-ray bursts (GRBs) whose progenitors are also thought to be massive stars. This suggests that the environments of hydrogen-poor SLSNe and GRBs are different. From the nondetection of Fe II fine-structure absorption lines, we derive a lower limit on the distance between the supernova and the narrow-line absorbing gas of 50 pc. The neutral gas responsible for the absorption in iPTF 13ajg exhibits a single narrow component with a low velocity width, Delta V = 76 km s(-1), indicating a low-mass host galaxy. No host galaxy emission lines are detected, leading to an upper limit on the unobscured star formation rate (SFR) of SFR[O II] < 0.07 M-circle dot yr(-1). Late-time imaging shows the iPTF 13ajg host galaxy to be faint, with g(AB) approximate to 27.0 and R-AB >= 26.0 mag, corresponding to M-B,M-Vega greater than or similar to -17.7 mag.

  • 372. Wang, Xiaofeng
    et al.
    Wang, Lifan
    Filippenko, Alexei V.
    Baron, Eddie
    Kromer, Markus
    Jack, Dennis
    Zhang, Tianmeng
    Aldering, Greg
    Antilogus, Pierre
    Arnett, W. David
    Baade, Dietrich
    Barris, Brian J.
    Benetti, Stefano
    Bouchet, Patrice
    Burrows, Adam S.
    Canal, Ramon
    Cappellaro, Enrico
    Carlberg, Raymond G.
    di Carlo, Elisa
    Challis, Peter J.
    Crotts, Arlin P. S.
    Danziger, John I.
    Della Valle, Massimo
    Fink, Michael
    Foley, Ryan J.
    Fransson, Claes
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Gal-Yam, Avishay
    Garnavich, Peter M.
    Gerardy, Chris L.
    Goldhaber, Gerson
    Hamuy, Mario
    Hillebrandt, Wolfgang
    Hoeflich, Peter
    Holland, Stephen T.
    Holz, Daniel E.
    Hughes, John P.
    Jeffery, David J.
    Jha, Saurabh W.
    Kasen, Dan
    Khokhlov, Alexei M.
    Kirshner, Robert P.
    Knop, Robert A.
    Kozma, Cecilia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Krisciunas, Kevin
    Lee, Brian C.
    Leibundgut, Bruno
    Lentz, Eric J.
    Leonard, Douglas C.
    Lewin, Walter H. G.
    Li, Weidong
    Livio, Mario
    Lundqvist, Peter
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Maoz, Dan
    Matheson, Thomas
    Mazzali, Paolo A.
    Meikle, Peter
    Miknaitis, Gajus
    Milne, Peter A.
    Mochnacki, Stefan W.
    Nomoto, Ken'ichi
    Nugent, Peter E.
    Oran, Elaine S.
    Panagia, Nino
    Perlmutter, Saul
    Phillips, Mark M.
    Pinto, Philip
    Poznanski, Dovi
    Pritchet, Christopher J.
    Reinecke, Martin
    Riess, Adam G.
    Ruiz-Lapuente, Pilar
    Scalzo, Richard A.
    Schlegel, Eric M.
    Schmidt, Brian P.
    Siegrist, James
    Soderberg, Alicia M.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Sonneborn, George
    Spadafora, Anthony
    Spyromilio, Jason
    Sramek, Richard A.
    Starrfield, Sumner G.
    Strolger, Louis G.
    Suntzeff, Nicholas B.
    Thomas, Rollin C.
    Tonry, John L.
    Tornambe, Amedeo
    Truran, James W.
    Turatto, Massimo
    Turner, Michael
    Van Dyk, Schuyler D.
    Weiler, Kurt W.
    Wheeler, J. Craig
    Wood-Vasey, Michael
    Woosley, Stanford E.
    Yamaoka, Hitoshi
    Evidence for type ia supernova diversity from ultraviolet observations with the hubble space telescope2012Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 749, nr 2, s. 126-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present ultraviolet (UV) spectroscopy and photometry of four Type Ia supernovae (SNe 2004dt, 2004ef, 2005M, and 2005cf) obtained with the UV prism of the Advanced Camera for Surveys on the Hubble Space Telescope. This data set provides unique spectral time series down to 2000 angstrom. Significant diversity is seen in the near-maximum-light spectra (similar to 2000-3500 angstrom) for this small sample. The corresponding photometric data, together with archival data from Swift Ultraviolet/Optical Telescope observations, provide further evidence of increased dispersion in the UV emission with respect to the optical. The peak luminositiesmeasured in the uvw1/F250W filter are found to correlate with the B-band light-curve shape parameter Delta m(15)(B), but with much larger scatter relative to the correlation in the broadband B band (e.g., similar to 0.4 mag versus similar to 0.2 mag for those with 0.8 mag < Delta m(15)(B) < 1.7 mag). SN 2004dt is found as an outlier of this correlation (at > 3 sigma), being brighter than normal SNe Ia such as SN 2005cf by similar to 0.9 mag and similar to 2.0 mag in the uvw1/F250W and uvm2/F220W filters, respectively. We show that different progenitor metallicity or line-expansion velocities alone cannot explain such a large discrepancy. Viewing-angle effects, such as due to an asymmetric explosion, may have a significant influence on the flux emitted in the UV region. Detailed modeling is needed to disentangle and quantify the above effects.

  • 373.
    West, Stuart L.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Lunnan, Ragnhild
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Omand, Conor M. B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kangas, T.
    Schulze, Steve
    Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Strotjohann, N. L.
    Yang, Sheng
    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).
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Perley, D.
    Yan, L.
    Chen, Ting-Wan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Chen, Z. H.
    Taggart, K.
    Fremling, C.
    Bloom, J. S.
    Drake, A.
    Graham, M. J.
    Kasliwal, M. M.
    Laher, R.
    Medford, M. S.
    Neill, J. D.
    Riddle, R.
    Shupe, D.
    SN 2020qlb: A hydrogen-poor superluminous supernova with well-characterized light curve undulations2023Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 670, artikkel-id A7Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Context. SN 2020qlb (ZTF20abobpcb) is a hydrogen-poor superluminous supernova (SLSN-I) that is among the most luminous (maximum Mg = −22.25 mag) and that has one of the longest rise times (77 days from explosion to maximum). We estimate the total radiated energy to be > 2.1 × 1051 erg. SN 2020qlb has a well-sampled light curve that exhibits clear near and post peak undulations, a phenomenon seen in other SLSNe, whose physical origin is still unknown.

    Aims. We discuss the potential power source of this immense explosion as well as the mechanisms behind its observed light curve undulations.

    Methods. We analyze photospheric spectra and compare them to other SLSNe-I. We constructed the bolometric light curve using photometry from a large data set of observations from the Zwicky Transient Facility (ZTF), Liverpool Telescope (LT), and Neil Gehrels Swift Observatory and compare it with radioactive, circumstellar interaction and magnetar models. Model residuals and light curve polynomial fit residuals are analyzed to estimate the undulation timescale and amplitude. We also determine host galaxy properties based on imaging and spectroscopy data, including a detection of the [O III]λ4363, auroral line, allowing for a direct metallicity measurement.

    Results. We rule out the Arnett 56Ni decay model for SN 2020qlb’s light curve due to unphysical parameter results. Our most favored power source is the magnetic dipole spin-down energy deposition of a magnetar. Two to three near peak oscillations, intriguingly similar to those of SN 2015bn, were found in the magnetar model residuals with a timescale of 32 ± 6 days and an amplitude of 6% of peak luminosity. We rule out centrally located undulation sources due to timescale considerations; and we favor the result of ejecta interactions with circumstellar material (CSM) density fluctuations as the source of the undulations.

  • 374. Whitesides, L.
    et al.
    Lunnan, Ragnhild
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). California Institute of Technology, USA.
    Kasliwal, M. M.
    Perley, D. A.
    Corsi, A.
    Cenko, S. B.
    Blagorodnova, N.
    Cao, Y.
    Cook, D. O.
    Doran, G. B.
    Frederiks, D. D.
    Fremling, Christoffer
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hurley, K.
    Karamehmetoglu, Emir
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kulkarni, S. R.
    Leloudas, G.
    Masci, F.
    Nugent, P. E.
    Ritter, A.
    Rubin, A.
    Savchenko, V.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Svinkin, D. S.
    Taddia, Francesco
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Vreeswijk, P.
    Wozniak, P.
    iPTF 16asu: A Luminous, Rapidly Evolving, and High-velocity Supernova2017Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 851, nr 2, artikkel-id 107Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Wide-field surveys are discovering a growing number of rare transients whose physical origin is not yet well understood. Here we present optical and UV data and analysis of intermediate Palomar Transient Factory (iPTF) 16asu, a luminous, rapidly evolving, high-velocity, stripped-envelope supernova ( SN). With a rest-frame rise time of just four. days and a peak absolute magnitude of M-g = -20.4 mag, the light curve of iPTF 16asu is faster and more luminous than that of previous rapid transients. The spectra of iPTF 16asu show a featureless blue continuum near peak that develops into an SN Ic-BL spectrum on the decline. We show that while the late-time light curve could plausibly be powered by Ni-56 decay, the early emission requires a different energy source. Nondetections in the X-ray and radio strongly constrain the energy coupled to relativistic ejecta to be at most comparable to the class of low-luminosity gamma-ray bursts (GRBs). We suggest that the early emission may have been powered by either a rapidly spinning-down magnetar or by shock breakout in an extended envelope of a very energetic explosion. In either scenario a central engine is required, making iPTF 16asu an intriguing transition object between superluminous SNe, SNe Ic-BL, and low-luminosity GRBs.

  • 375. Wollaeger, Ryan T.
    et al.
    Korobkin, Oleg
    Fontes, Christopher J.
    Rosswog, Stephan K.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Even, Wesley P.
    Fryer, Christopher L.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hungerford, Aimee L.
    Van Rossum, Daniel R.
    Wollaber, Allan B.
    Impact of ejecta morphology and composition on the electromagnetic signatures of neutron star mergers2018Inngår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 478, nr 3, s. 3298-3334Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The electromagnetic transients accompanying compact binary mergers (gamma-ray bursts, after-glows and 'macronovae') are crucial to pinpoint the sky location of gravitational wave sources. Macronovae are caused by the radioactivity from freshly synthesized heavy elements, e.g. from dynamic ejecta and various types of winds. We study macronova signatures by using multidimensional radiative transfer calculations. We employ the radiative transfer code SUPERNU and state-of-the-art LTE opacities for a few representative elements from the wind and dynamical ejecta (Cr, Pd, Se, Te, Br, Zr, Sm, Ce, Nd, U) to calculate synthetic light curves and spectra for a range of ejecta morphologies. The radioactive power of the resulting macronova is calculated with the detailed input of decay products. We assess the detection prospects for our most complex models, based on the portion of viewing angles that are sufficiently bright, at different cosmological redshifts (z). The brighter emission from the wind is unobscured by the lanthanides (or actinides) in some of the models, permitting non-zero detection probabilities for redshifts up to z = 0.07. We also find that the nuclear mass model and the resulting radioactive heating rate are crucial for the detectability. While for the most pessimistic heating rate (from the finite range droplet model) no reasonable increase in the ejecta mass or velocity, or wind mass or velocity, can possibly make the light curves agree with the observed near-infrared excess after GRB130603B, a more optimistic heating rate (from the Duflo-Zuker model) leads to good agreement. We conclude that future reliable macronova observations would constrain nuclear heating rates, and consequently help constrain nuclear mass models.

  • 376. Wood-Vasey, W. M.
    et al.
    Miknaitis, G.
    Stubbs, C. W.
    Jha, S.
    Riess, A. G.
    Garnavich, P. M.
    Kirshner, R. P.
    Aguilera, C.
    Becker, A. C.
    Blackman, J. W.
    Blondin, S.
    Challis, P.
    Clocchiatti, A.
    Conley, A.
    Covarrubias, R.
    Davis, T. M.
    Filippenko, A. V.
    Foley, R. J.
    Garg, A.
    Hicken, M.
    Krisciunas, K.
    Leibundgut, B.
    Li, W.
    Matheson, T.
    Miceli, A.
    Narayan, G.
    Pignata, G.
    Prieto, J. L.
    Rest, A.
    Salvo, M. E.
    Schmidt, B. P.
    Smith, R. C.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Spyromilio, J.
    Tonry, J. L.
    Suntzeff, N. B.
    Zenteno, A.
    Observational constraints on the nature of dark energy: First cosmological results from the ESSENCE supernova survey2007Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 666, nr 2, s. 694-715Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    We present constraints on the dark energy equation-of-state parameter, w = P/(rho c(2)), using 60 SNe Ia fromthe ESSENCE supernova survey. We derive a set of constraints on the nature of the dark energy assuming a flat universe. By including constraints on (Omega(M), w) from baryon acoustic oscillations, we obtain a value for a static equation-of-state parameter w = -1:05(-0.12)(+0: 13) (stat 1 sigma) +/- 0: 13 (sys) and Omega(M) = 0:274(-0.020)(+0:033) (stat 1 sigma) with a bestfit chi(2)/dof of 0.96. These results are consistent with those reported by the Supernova Legacy Survey from the first year of a similar program measuring supernova distances and redshifts. We evaluate sources of systematic error that afflict supernova observations and present Monte Carlo simulations that explore these effects. Currently, the largest systematic with the potential to affect our measurements is the treatment of extinction due to dust in the supernova host galaxies. Combining our set of ESSENCE SNe Ia with the first-results Supernova Legacy Survey SNe Ia, we obtain a joint constraint of w = -1:07(-0: 09)(+0:09) (stat 1 sigma) +/- 0: 13 ( sys), Omega(M) 0:267(-0:028)(+0:028) (stat 1 sigma) with a best-fit chi(2)/dof of 0.91. The current global SN Ia data alone rule out empty (Omega(M) = 0), matter-only Omega(M) = 0: 3, and Omega(M) = 1 universes at > 4.5 sigma. The current SN Ia data are fully consistent with a cosmological constant.

  • 377. Xu, D.
    et al.
    de Ugarte Postigo, A.
    Leloudas, Georgios
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kruehler, T.
    Cano, Z.
    Hjorth, J.
    Malesani, D.
    Fynbo, J. P. U.
    Thoene, C. C.
    Sanchez-Ramirez, R.
    Schulze, S.
    Jakobsson, P.
    Kaper, L.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Watson, D. J.
    Cabrera-Lavers, A.
    Cao, C.
    Covino, S.
    Flores, H.
    Geier, S.
    Gorosabel, J.
    Hu, S. M.
    Milvang-Jensen, B.
    Sparre, M.
    Xin, L. P.
    Zhang, T. M.
    Zheng, W. K.
    Zou, Y. C.
    DISCOVERY OF THE BROAD-LINED TYPE Ic SN 2013cq ASSOCIATED WITH THE VERY ENERGETIC GRB 130427A2013Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 776, nr 2, s. 98-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Long-duration gamma-ray bursts (GRBs) at z < 1 are found in most cases to be accompanied by bright, broadlined Type Ic supernovae (SNe Ic-BL). The highest-energy GRBs are mostly located at higher redshifts, where the associated SNe are hard to detect observationally. Here, we present early and late observations of the optical counterpart of the very energetic GRB 130427A. Despite its moderate redshift, z = 0.3399+/-0.0002, GRB 130427A is at the high end of the GRB energy distribution, with an isotropic-equivalent energy release of E-iso similar to 9.6 x 10(53) erg, more than an order of magnitude more energetic than other GRBs with spectroscopically confirmed SNe. In our dense photometric monitoring, we detect excess flux in the host-subtracted r-band light curve, consistent with that expected from an emerging SN, similar to 0.2 mag fainter than the prototypical SN 1998bw. A spectrum obtained around the time of the SN peak (16.7 days after the GRB) reveals broad undulations typical of SNe Ic-BL, confirming the presence of an SN, designated SN 2013cq. The spectral shape and early peak time are similar to those of the high expansion velocity SN 2010bh associated with GRB 100316D. Our findings demonstrate that high-energy, long-duration GRBs, commonly detected at high redshift, can also be associated with SNe Ic-BL, pointing to a common progenitor mechanism.

  • 378. Xu, D.
    et al.
    Starling, R. L. C.
    Fynbo, J. P. U.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Yost, S.
    Watson, D.
    Foley, S.
    O'Brien, P. T.
    Hjorth, J.
    In Search of Progenitors for Supernovaless Gamma-Ray Bursts 060505 and 060614: Re-examination of Their Afterglows2009Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 696, nr 1, s. 971-979Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    GRB 060505 and GRB 060614 are nearby long-duration gamma-ray bursts (LGRBs) without accompanying supernovae (SNe) down to very strict limits. They thereby challenge the conventional LGRB-SN connection and naturally give rise to the question: are there other peculiar features in their afterglows which would help shed light on their progenitors? To answer this question, we combine new observational data with published data and investigate the multiband temporal and spectral properties of the two afterglows. We find that both afterglows can be well interpreted within the framework of the jetted standard external shock wave model, and that the afterglow parameters for both bursts fall well within the range observed for other LGRBs. Hence, from the properties of the afterglows there is nothing to suggest that these bursts should have another progenitor than other LGRBs. Recently, Swift-discovered GRB 080503 also has the spike + tail structure during its prompt γ-ray emission seemingly similar to GRB 060614. We analyze the prompt emission of this burst and find that this GRB is actually a hard-spike + hard-tail burst with a spectral lag of 0.8 ± 0.4 s during its tail emission. Thus, the properties of the prompt emission of GRB 060614 and GRB 080503 are clearly different, motivating further thinking of GRB classification (and even identification of faint core-collapse SNe). Finally, we note that, whereas the progenitor of the two SN-less bursts remains uncertain, the core-collapse origin for the SN-less bursts would be quite certain if a windlike environment can be observationally established, e.g., from an optical decay faster than the X-ray decay in the afterglow's slow cooling phase. Based on observations collected at the European Organization for Astronomical Research in the Southern Hemisphere, Chile, under programs 077.D-0661 and 177.A-0591.

  • 379. Yan, Lin
    et al.
    Lunnan, R.
    Perley, D. A.
    Gal-Yam, A.
    Yaron, O.
    Roy, Rupak
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Quimby, R.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Fremling, Christoffer
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Leloudas, G.
    Cenko, S. B.
    Vreeswijk, P.
    Graham, M. L.
    Howell, D. A.
    De Cia, A.
    Ofek, E. O.
    Nugent, P.
    Kulkarni, S. R.
    Hosseinzadeh, G.
    Masci, F.
    McCully, C.
    Rebbapragada, U. D.
    Wozniak, P.
    Hydrogen-poor Superluminous Supernovae with Late-time H alpha Emission: Three Events From the Intermediate Palomar Transient Factory2017Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 848, nr 1, artikkel-id 6Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present observations of two new hydrogen-poor superluminous supernovae (SLSN-I), iPTF15esb and iPTF16bad, showing late-time H alpha emission with line luminosities of (1-3) x 10(41) erg s(-1) and velocity widths of (4000-6000) km s(-1). Including the previously published iPTF13ehe, this makes up a total of three such events to date. iPTF13ehe is one of the most luminous and the slowest evolving SLSNe-I, whereas the other two are less luminous and fast decliners. We interpret this as a result of the ejecta running into a neutral H-shell located at a radius of similar to 10(16) cm. This implies that violent mass loss must have occurred several decades before the supernova explosion. Such a short time interval suggests that eruptive mass loss could be common shortly before core collapse, and more importantly helium is unlikely to be completely stripped off the progenitor and could be present in the ejecta. It is a mystery why helium features are not detected, even though nonthermal energy sources, capable of ionizing He, may exist as suggested by the O II absorption series in the early-time spectra. Our late-time spectra (+240 days) appear to have intrinsically lower [O I] 6300 angstrom luminosities than that of SN2015bn and SN2007bi, which is possibly an indication of less oxygen (<10 M-circle dot). The blueshifted H alpha emission relative to the hosts for all three events may be in tension with the binary model proposed for iPTF13ehe. Finally, iPTF15esb has a peculiar light curve (LC) with three peaks separated from one another by similar to 22 days. The LC undulation is stronger in bluer bands. One possible explanation is ejecta-circumstellar medium interaction.

  • 380. Yan, Lin
    et al.
    Perley, D. A.
    Schulze, S.
    Lunnan, Ragnhild
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    De, K.
    Chen, Z. H.
    Fremling, C.
    Gal-Yam, A.
    Taggart, K.
    Chen, Ting-Wan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Andreoni, I.
    Bellm, E. C.
    Cunningham, V.
    Dekany, R.
    Duev, D. A.
    Fransson, Claes
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Laher, R. R.
    Hankins, M.
    Ho, A. Y. Q.
    Jencson, J. E.
    Kaye, S.
    Kulkarni, S. R.
    Kasliwal, M. M.
    Golkhou, V. Z.
    Graham, M.
    Masci, F. J.
    Miller, A. A.
    Neill, J. D.
    Ofek, E.
    Porter, M.
    Mroz, P.
    Reiley, D.
    Riddle, R.
    Rigault, M.
    Rusholme, B.
    Shupe, D. L.
    Soumagnac, M. T.
    Smith, R.
    Tartaglia, Leonardo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Yao, Y.
    Yaron, O.
    Helium-rich Superluminous Supernovae from the Zwicky Transient Facility2020Inngår i: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 902, nr 1, artikkel-id L8Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Helium is expected to be present in the massive ejecta of some hydrogen-poor superluminous supernovae (SLSN-I). However, until now only one event has been identified with He features in its photospheric spectra (PTF10hgi). We present the discovery of a new He-rich SLSN-I, ZTF19aawfbtg (SN2019hge), atz = 0.0866. This event has more than 10 optical spectra at phases from -41 to +103 days relative to the peak, most of which match well with that of PTF10hgi. Confirmation comes from a near-IR spectrum taken at +34 days, revealing Heifeatures with P-Cygni profiles at 1.083 and 2.058 mu m. Using the optical spectra of PTF10hgi and SN2019hge as templates, we examined 70 other SLSNe-I discovered by Zwicky Transient Facility in the first two years of operation and found five additional SLSNe-I with distinct He-features. The excitation of Heiatoms in normal core-collapse supernovae requires nonthermal radiation, as proposed by previous studies. These He-rich events cannot be explained by the traditional(56)Ni mixing model because of their blue spectra, high peak luminosities, and long rise timescales. Magnetar models offer a possible solution since pulsar winds naturally generate high-energy particles, potential sources of nonthermal excitation. An alternative model is the interaction between the ejecta and dense H-poor circumstellar material, which may be supported by observed undulations in the light curves. These six SLSNe-Ib have relatively low-peak luminosities (rest frameM(g) = -20.06 0.16).

  • 381.
    Yang, Sheng
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Henan Academy of Sciences, People's Republic of China.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    HAFFET: Hybrid Analytic Flux FittEr for Transients2023Inngår i: Astrophysical Journal Supplement Series, ISSN 0067-0049, E-ISSN 1538-4365, Vol. 269, nr 2, artikkel-id 40Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The progenitors for many types of supernovae (SNe) are still unknown, and an approach to diagnose their physical origins is to investigate the light-curve brightness and shape of a large set of SNe. However, it is often difficult to compare and contrast the existing sample studies due to differences in their approaches and assumptions, for example, in how to eliminate host galaxy extinction, and this might lead to systematic errors when comparing the results. We therefore introduce the Hybrid Analytic Flux FittEr for Transients (HAFFET), a Python-based software package that can be applied to download photometric and spectroscopic data for transients from open online sources, derive bolometric light curves, and fit them to semianalytical models for estimation of their physical parameters. In a companion study, we have investigated a large collection of SNe Ib and Ic observed with the Zwicky Transient Facility (ZTF) with HAFFET, and here we detail the methodology and the software package to encourage more users. As large-scale surveys such as ZTF and LSST continue to discover increasing numbers of transients, tools such as HAFFET will be critical for enabling rapid comparison of models against data in statistically consistent, comparable, and reproducible ways. Additionally, HAFFET is created with a graphical user interface mode, which we hope will boost the efficiency and make the usage much easier (https://github.com/saberyoung/HAFFET).

  • 382.
    Yang, Sheng
    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).
    Chen, Janet Ting-Wan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kool, Erik C.
    Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Lunnan, Ragnhild
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Schulze, S.
    Strotjohann, N.
    Horesh, A.
    Kasliwal, M.
    Kupfer, T.
    Mahabal, A. A.
    Masci, F. J.
    Nugent, P.
    Perley, D. A.
    Riddle, R.
    Rusholme, B.
    Sharma, Y.
    Is supernova SN 2020faa an iPTF14hls look-alike?2021Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 646, artikkel-id A22Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Context. We present observations of ZTF20aatqesi (SN 2020faa). This Type II supernova (SN) displays a luminous light curve (LC) that started to rebrighten from an initial decline. We investigate this in relation to the famous SN iPTF14hls, which received a great deal of attention and multiple interpretations in the literature, but whose nature and source of energy still remain unknown.

    Aims. We demonstrate the great similarity between SN 2020faa and iPTF14hls during the first 6 months, and use this comparison to forecast the evolution of SN 2020faa and to reflect on the less well observed early evolution of iPTF14hls.

    Methods. We present and analyse our observational data, consisting mainly of optical LCs from the Zwicky Transient Facility in the gri bands and of a sequence of optical spectra. We construct colour curves and a bolometric lc, and we compare ejecta-velocity and black-body radius evolutions for the two supernovae (SNe) and for more typical Type II SNe.

    Results. The LCs show a great similarity with those of iPTF14hls over the first 6 months in luminosity, timescale, and colour. In addition, the spectral evolution of SN 2020faa is that of a Type II SN, although it probes earlier epochs than those available for iPTF14hls.

    Conclusions. The similar LC behaviour is suggestive of SN 2020faa being a new iPTF14hls. We present these observations now to advocate follow-up observations, since most of the more striking evolution of SN iPTF14hls came later, with LC undulations and a spectacular longevity. On the other hand, for SN 2020faa we have better constraints on the explosion epoch than we had for iPTF14hls, and we have been able to spectroscopically monitor it from earlier phases than was done for the more famous sibling.

  • 383.
    Yang, Sheng
    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).
    Strotjohann, N. L.
    Schulze, Steve
    Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Lunnan, Ragnhild
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kool, Erik C.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Fremling, C.
    Perley, D.
    Ofek, E.
    Schweyer, Tassilo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bellm, E. C.
    Kasliwal, M. M.
    Masci, F. J.
    Rigault, M.
    Yang, Y.
    A low-energy explosion yields the underluminous Type IIP SN 2020cxd2021Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 655, artikkel-id A90Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Context. We present our observations and analysis of SN 2020cxd, a low-luminosity (LL), long-lived Type IIP supernova (SN). This object is a clear outlier in the magnitude-limited SN sample recently presented by the Zwicky Transient Facility’s (ZTF) Bright Transient Survey.

    Aims. We demonstrate that SN 2020cxd is an additional member of the group of LL SNe and we discuss the rarity of LL SNe in the context of the ZTF survey. We consider how further studies of these faintest members of the core-collapse (CC) SN family might help improve the general understanding of the underlying initial mass function for stars that explode.

    Methods. We used optical light curves (LCs) from the ZTF in the gri bands and several epochs of ultraviolet data from the Neil Gehrels Swift observatory as well as a sequence of optical spectra. We constructed the colour curves and a bolometric LC. Then we compared the evolution of the ejecta velocity and black-body temperature for LL SNe as well as for typical Type II SNe. Furthermore, we adopted a Monte Carlo code that fits semi-analytic models to the LC of SN 2020cxd, which allows for the estimation of the physical parameters. Using our late-time nebular spectra, we also make a comparison against SN II spectral synthesis models from the literature to constrain the progenitor properties of SN 2020cxd.

    Results. The LCs of SN 2020cxd show a great similarity with those of LL SNe IIP in terms of luminosity, timescale, and colours. Also, the spectral evolution of SN 2020cxd is that of a Type IIP SN. The spectra show prominent and narrow P-Cygni lines, indicating low expansion velocities. This is one of the faintest LL SNe observed, with an absolute plateau magnitude of Mr = −14.5 mag and also one with the longest plateau lengths, with a duration of 118 days. Finally, the velocities measured from the nebular emission lines are among the lowest ever seen in a SN, with an intrinsic full width at half maximum value of 478 km s−1. The underluminous late-time exponential LC tail indicates that the mass of 56Ni ejected during the explosion is much smaller than the average of normal SNe IIP, we estimate M56Ni = 0.003 M. The Monte Carlo fitting of the bolometric LC suggests that the progenitor of SN 2020cxd had a radius of R0 = 1.3 × 1013 cm, kinetic energy of Ekin = 4.3 × 1050 erg, and ejecta mass of Mej = 9.5 M. From the bolometric LC, we estimated the total radiated energy Erad = 1.52 × 1048 erg. Using our late-time nebular spectra, we compared these results against SN II spectral synthesis models to constrain the progenitor zero-age main sequence mass and found that it is likely to be ≲15 M.

    Conclusions. SN 2020cxd is a LL Type IIP SN. The inferred progenitor parameters and the features observed in the nebular spectrum favour a low-energy, Ni-poor, iron CC SN from a low-mass (∼12 M) red supergiant.

  • 384. Yao, Yuhan
    et al.
    De, Kishalay
    Kasliwal, Mansi M.
    Ho, Anna Y. Q.
    Schulze, Steve
    Li, Zhihui
    Kulkarni, S. R.
    Fruchter, Andrew
    Rubin, David
    Perley, Daniel A.
    Fuller, Jim
    Piro, Anthony L.