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LONG-DURATION SUPERLUMINOUS SUPERNOVAE AT LATE TIMES

Anders JerkstrandMax-Planck Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching, GermanyStephen SmarttAstrophysics Research Centre, School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN, UKC. InserraAstrophysics Research Centre, School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN, UKM. NichollHarvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USAT. W. ChenMax-Planck-Institut für Extraterrestrische Physik, Giessenbachstrasse 1, D-85748, Garching, GermanyT. KrühlerMax-Planck-Institut für Extraterrestrische Physik, Giessenbachstrasse 1, D-85748, Garching, GermanyJ. SollermanThe Oskar Klein Centre, Department of Astronomy, Stockholm University, AlbaNova, SE-10691 Stockholm, SwedenS. TaubenbergerMax-Planck Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching, GermanyA. Gal‐YamBenoziyo Center for Astrophysics, Weizmann Institute of Science, 76100 Rehovot, IsraelE. KankareAstrophysics Research Centre, School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN, UKK. MaguireAstrophysics Research Centre, School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN, UKMorgan FraserInstitute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UKStefano ValentiDepartment of Physics, University of California, Davis, CA 95616, USAM. SullivanDepartment of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, UKR. CartierDepartment of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, UKD. R. YoungAstrophysics Research Centre, School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN, UK

2017en

ABI

Annotatsiya

ABSTRACT Nebular-phase observations and spectral models of Type Ic superluminous supernovae (SLSNe) are presented. LSQ14an and SN 2015bn both display late-time spectra similar to galaxy-subtracted spectra of SN 2007bi, and the class shows strong similarity with broad-lined SNe Ic such as SN 1998bw. Near-infrared observations of SN 2015bn show a strong Ca ii triplet, O i 9263, O i 1.13 μ m, and Mg i 1.50 μ m, but no distinct He, Si, or S emission. The high Ca ii NIR/[Ca ii ] 7291, 7323 ratio of ∼2 indicates a high electron density of cm −3 . Spectral models of oxygen-zone emission are investigated to put constraints on the emitting region. Models require M ⊙ to produce enough [O i ] 6300, 6364 luminosity, irrespective of the powering situation and the density. The high oxygen-zone mass, supported by high estimated magnesium masses, points to explosions of massive CO cores, requiring . Collisions of pair-instability pulsations do not provide enough mass to account for the emission. [O ii ] and [O iii ] lines emerge naturally in many models, which strengthens the identification of broad [O ii ] 7320, 7330, [O iii ] 4363, and [O iii ] 4959, 5007 in some spectra. A small filling factor for the O/Mg zone is needed to produce enough luminosity in Mg i ] 4571, Mg i 1.504 μ m, and O i recombination lines, which shows that the ejecta is clumped. We review the constraints from the nebular spectral modeling in the context of the various scenarios proposed for SLSNe.

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DOI: 10.3847/1538-4357/835/1/13

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