The radial distribution of supernovae compared to star formation tracers

Abstract

ABSTRACT Given the limited availability of direct evidence (pre-explosion observations) for supernova (SN) progenitors, the location of supernovae (SNe) within their host galaxies can be used to set limits on one of their most fundamental characteristics, their initial progenitor mass. We present our constraints on SN progenitors derived by comparing the radial distributions of 80 SNe in the Survey for Ionised Neutral Gas Galaxies (SINGG) and Survey of Ultraviolet emission in Neutral Gas Galaxies (SUNGG) to the R-band, H α, and UV light distributions of the 55 host galaxies. The strong correlation of Type Ia SNe with R-band light is consistent with models containing only low-mass progenitors, reflecting earlier findings. When we limit the analysis of Type II SNe to apertures containing 90 per cent of the total flux, the radial distribution of these SNe best traces far-ultraviolet emission, consistent with recent direct detections indicating Type II SNe have moderately massive red supergiant progenitors. Stripped-envelope (SE) SNe have the strongest correlation with H α fluxes, indicative of very massive progenitors (M* ≳ 20 M⊙). This result contradicts a small, but growing, number of direct detections of SE SN progenitors, indicating they are moderately massive binary systems. Our result is consistent, however, with a recent population analysis, suggesting binary SE SN progenitor masses are regularly underestimated. SE SNe are centralized with respect to Type II SNe and there are no SE SNe recorded beyond half the maximum disc radius in the optical and one third the disc radius in the ultraviolet. The absence of SE SNe beyond these distances is consistent with reduced massive star formation efficiencies in the outskirts of the host galaxies.