Signatures of an eruptive phase before the explosion of the peculiar core-collapse SN 2013gc
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Fecha
2019-01
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en
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Monthly Notices of the Royal Astronomical Society
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Attribution 4.0 International (CC BY 4.0)
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https://creativecommons.org/licenses/by/4.0/
Resumen
We present photometric and spectroscopic analysis of the peculiar core-collapse supernova (SN) 2013gc, spanning 7 yr of observations. The light curve shows an early maximum followed by a fast decline and a phase of almost constant luminosity. At +200 d from maximum, a brightening of 1 mag is observed in all bands, followed by a steep linear luminosity decline after +300 d. In archival images taken between 1.5 and 2.5 yr before the explosion, a weak source is visible at the supernova location, with mag ≈20. The early supernova spectra show Balmer lines, with a narrow (∼560 km s-1) P-Cygni absorption superimposed on a broad (∼3400 km s-1) component, typical of Type IIn events. Through a comparison of colour curves, absolute light curves, and spectra of SN 2013gc with a sample of supernovae IIn, we conclude that SN 2013gc is a member of the so-called Type IId subgroup. The complex profile of the Hα line suggests a composite circumstellar medium geometry, with a combination of lower velocity, spherically symmetric gas, and a more rapidly expanding bilobed feature. This circumstellar medium distribution has been likely formed through major mass-loss events that we directly observed from 3 yr before the explosion. The modest luminosity (MI ∼-16.5 near maximum) of SN 2013gc at all phases, the very small amount of ejected 56Ni (of the order of 10-3 M⊙), the major pre-supernova stellar activity, and the lack of prominent [O I] lines in the late-time spectra support a fall-back core-collapse scenario for the massive progenitor of SN 2013gc.
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Indexación Scopus
Palabras clave
Supernovae: general, Supernovae: individual: SN2013gc, SN1994aj, SN1996al, SN1996L, SN2000P
Citación
Monthly Notices of the Royal Astronomical Society Volume 482, Issue 2, Pages 2750 - 2769 January 2019
DOI
10.1093/mnras/sty2870