Emission line models for the lowest mass core-collapse supernovae – I. Case study of a 9 M⊙ one-dimensional neutrino-driven explosion. Issue 1 (13th November 2017)

• Record Type: Journal Article
• Authors: Jerkstrand, A; Ertl, T; Janka, H-T; Müller, E; Sukhbold, T; Woosley, S E
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 475:Issue 1(2018)
• Page Start: 277
• Page End: 305
• Publication Date: 2017-11-13
• Subjects: hydrodynamics -- line: formation -- radiative transfer -- stars: evolution -- supernovae: general -- supernovae: individual: SN 1997D, SN 2005cs, SN 2008bk; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stx2877
• Languages: English
• ISSNs: 0035-8711

Abstract

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 M ZAMS = 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; 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 58 Ni/ 56 Ni 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.