Статья

SUPERLUMINOUS SUPERNOVA SN 2015bn IN THE NEBULAR PHASE: EVIDENCE FOR THE ENGINE-POWERED EXPLOSION OF A STRIPPED MASSIVE STAR

M. NichollHarvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA; [email protected]E. BergerHarvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA; [email protected]R. MarguttiCenter for Cosmology and Particle Physics, New York University, 4 Washington Place, New York, NY 10003, USAR. ChornockAstrophysical Institute, Department of Physics and Astronomy, 251B Clippinger Lab, Ohio University, Athens, OH 45701, USAP. K. BlanchardHarvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA; [email protected]Anders JerkstrandAstrophysics Research Centre, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN, UKStephen SmarttAstrophysics Research Centre, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN, UKI. ArcaviLas Cumbres Observatory Global Telescope, 6740 Cortona Drive, Suite 102, Goleta, CA 93111, USAP. ChallisHarvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA; [email protected]K. C. ChambersInstitute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822, USAT. W. ChenMax-Planck-Institut für Extraterrestrische Physik, Giessenbachstraße 1, D-85748, Garching, GermanyP. S. CowperthwaiteHarvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA; [email protected]A. Gal‐YamBenoziyo Center for Astrophysics, Weizmann Institute of Science, Rehovot 76100, IsraelGriffin HosseinzadehLas Cumbres Observatory Global Telescope, 6740 Cortona Drive, Suite 102, Goleta, CA 93111, USAD. A. HowellLas Cumbres Observatory Global Telescope, 6740 Cortona Drive, Suite 102, Goleta, CA 93111, USAC. InserraAstrophysics Research Centre, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN, UKE. KankareAstrophysics Research Centre, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN, UKE. A. MagnierInstitute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822, USAK. MaguireAstrophysics Research Centre, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN, UKP. A. MazzaliAstrophysics Research Institute, Liverpool John Moores University, IC2, Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF, UKCurtis McCullyLas Cumbres Observatory Global Telescope, 6740 Cortona Drive, Suite 102, Goleta, CA 93111, USAD. MilisavljevicHarvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA; [email protected]K. SmithAstrophysics Research Centre, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN, UKS. TaubenbergerEuropean Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching, GermanyStefano ValentiDepartment of Physics, University of California, Davis, CA 95616, USAR. J. WainscoatInstitute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822, USAO. YaronBenoziyo Center for Astrophysics, Weizmann Institute of Science, Rehovot 76100, IsraelD. R. YoungAstrophysics Research Centre, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN, UK

2016en

ABI

Аннотация

ABSTRACT We present nebular-phase imaging and spectroscopy for the hydrogen-poor superluminous supernova (SLSN) SN 2015bn, at redshift z = 0.1136, spanning +250–400 days after maximum light. The light curve exhibits a steepening in the decline rate from 1.4 mag (100 days) −1 to 1.7 mag (100 days) −1 , suggestive of a significant decrease in the opacity. This change is accompanied by a transition from a blue continuum superposed with photospheric absorption lines to a nebular spectrum dominated by emission lines of oxygen, calcium, and magnesium. There are no obvious signatures of circumstellar interaction or large 56 Ni mass. We show that the spectrum at +400 days is virtually identical to a number of energetic SNe Ic such as SN 1997dq, SN 2012au, and SN 1998bw, indicating similar core conditions and strengthening the link between “hypernovae”/long gamma-ray bursts and SLSNe. A single explosion mechanism may unify these events that span absolute magnitudes of −22 < M B < −17. Both the light curve and spectrum of SN 2015bn are consistent with an engine-driven explosion ejecting 7–30 M ⊙ of oxygen-dominated ejecta (for reasonable choices in temperature and opacity). A strong and relatively narrow O i λ 7774 line, seen in a number of these energetic events but not in normal supernovae, may point to an inner shell that is the signature of a central engine.

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Идентификаторы

DOI: 10.3847/2041-8205/828/2/l18

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Цитирований: 3Использованных источников: 0

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