Emission line models for the lowest mass core-collapse supernovae - I. Case study of a 9 M$__s13sun_s19$ one-dimensional neutrino-driven explosion

Jerkstrand, A. and Ertl, T. and Janka, H.-T. and M�ller, E. and Sukhbold, T. and Woosley, S.~E.

Keywords

hydrodynamics, line: formation, radiative transfer, stars: evolution, supernovae: general, supernovae: individual: SN 1997D, SN 2005cs, SN 2008bk

Abstract

A large fraction of core-collapse supernovae (CCSNe), 30-50 per cent, are expected to originate from the low-mass end of progenitors with MZAMS = 8-12 M⊙. However, degeneracy effects make stellar evolution modelling of such stars challenging, and few predictions for their supernova light curves and spectra have been presented. Here, we calculate synthetic nebular spectra of a 9 M⊙ Fe CCSN model exploded with the neutrino mechanism. The model predicts emission lines with FWHM ˜ 1000 km s-1, including signatures from each deep layer in the metal core. We compare this model to the observations of the three subluminous IIP SNe with published nebular spectra_s19 SN 1997D, SN 2005cs and SN 2008bk. The predictions of both line profiles and luminosities are in good agreement with SN 1997D and SN 2008bk. The close fit of a model with no tuning parameters provides strong evidence for an association of these objects with low-mass Fe CCSNe. For SN 2005cs, the interpretation is less clear, as the observational coverage ended before key diagnostic lines from the core had emerged. We perform a parametrized study of the amount of explosively made stable nickel, and find that none of these three SNe show the high 58Ni/56Ni ratio predicted by current models of electron capture SNe (ECSNe) and ECSN-like explosions. Combined with clear detection of lines from O and He shell material, these SNe rather originate from Fe core progenitors. We argue that the outcome of self-consistent explosion simulations of low-mass stars, which gives fits to many key observables, strongly suggests that the class of subluminous Type IIP SNe is the observational counterpart of the lowest mass CCSNe.

Information

Published
2018 as article
mnras, 475 - page(s): 277-305
Contact
PD Dr. Hans-Thomas Janka
Type
theoretical work
Links
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1710.04508

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