Observational Clues to the Progenitors of Type Ia Supernovae

Abstract

Type-Ia supernovae (SNe Ia) are important distance indicators, element factories, cosmic-ray accelerators, kinetic-energy sources in galaxy evolution, and endpoints of stellar binary evolution. It has long been clear that a SN Ia must be the runaway thermonuclear explosion of a degenerate carbon-oxygen stellar core, most likely a white dwarf (WD). However, the specific progenitor systems of SNe Ia, and the processes that lead to their ignition, have not been identified. Two broad classes of progenitor binary systems have long been considered: single-degenerate (SD), in which a WD gains mass from a non-degenerate star; and doubledegenerate (DD), involving the merger of two WDs. New theoretical work has enriched these possibilities with some interesting updates and variants. We review the significant recent observational progress in addressing the progenitor problem. We consider clues that have emerged from the observed properties of the various proposed progenitor populations, from studies of their sites -pre-and post-explosion, from analysis of the explosions themselves, and from the measurement of event rates. The recent nearby and well-studied event, SN 2011fe, has been particularly revealing. The observational results are not yet conclusive, and sometimes prone to competing theoretical interpretations. Nevertheless, it appears that DD progenitors, long considered the underdog option, could be behind some, if not all, SNe Ia. We point to some directions that may lead to future progress.

Constraining the progenitor of the Type Ia Supernova SN 2012cg

“…However, no (or a very weak) interaction signature from the SN-companion (because of a small companion) or SN-CSM (due to the low density CSM) interaction is predicted in this scenario, making it extremely difficult to explain the early excess UV luminosity seen in SN 2012cg. Also, the exact spin-down timescale of the WD in this model is quite unknown (Maoz, Mannucci & Nelemans 2014).…”

A simple and general method for solving detailed chemical evolution with delayed production of iron and other chemical elements

“…The function DTDIa(τ ) physically represents the (unnormalized) number of Type Ia SNe, which are expected to explode at the time t = τ from a burst of star formation at t = 0, per unit mass of the simple stellar population (SSP) and per unit time of duration of the burst. Observational evidence suggests an integrated number of Type Ia SNe, which is ∼ 1 SN per M = 10 3 M of stellar mass formed, with a scatter of about 2-10 around this value (Bell et al 2003;Maoz et al 2014). In this work, the normalization constants of the examined DTDs are chosen so as to fulfill this criterion; in particular, the constant CIa is computed by requiring the following constraint:…”

LATE-TIME PHOTOMETRY OF TYPE IA SUPERNOVA SN 2012cg REVEALS THE RADIOACTIVE DECAY OF 57Co

“…While there is a wide consensus that SNe Ia are the result of a thermonuclear explosion of a carbon-oxygen white dwarf, it is still unclear how the white dwarf is detonated and consumed (for a recent review, see Maoz et al 2014). Röpke et al (2012) have used the leptonic energy injection mechanisms due to the decays of 57 Co and 55 Fe described above to provide a testable prediction for two popular SN Ia explosion scenarios: the "delayed-detonation" and "violent merger" models (Khokhlov 1991; Pakmor et al 2011Pakmor et al , 2012.…”