CfA OIR Division Lunch Talks
Wednesday, April 23, 2014, 11:00 am, Pratt Conference Room

The X-ray Emission From Young Supernovae as a Probe of their Progenitors

Vikram Dwarkadas (University of Chicago)

Even after several decades of study, the progenitor stars of supernovae (SNe) have proven difficult to identify. The identification of progenitors has generally been the purview of optical astronomy, aided in part by stellar evolution models. But observations at other wavelengths can also provide several hints about the progenitors. We have aggregated together data available in the literature, or analysed by us, to compute the X-ray lightcurves of almost all young SNe. We use these, coupled with analytical and numerical simulations, to investigate the SN expansion, the characteristics of the medium into which they are expanding, and the implications for their progenitors. We explore all SN types, with emphasis on Type IIP and Type IIn SNe. IIPs have the lowest X-ray luminosities, which is surprising given the high mass-loss rate, and low velocity, winds expected from their red supergiant (RSG) progenitors, and therefore the high density medium into which IIP SNe are expected to expand into. We show that the low X-ray luminosity sets a limit on the mass-loss rate, and thereby initial mass of a RSG star which can become a Type IIP progenitor. This initial mass limit, of about 19 solar masses, is consistent with that obtained via direct optical progenitor identification. IIns are observed to have high X-ray luminosities in general, but their light curves are very diverse, with some of them tending to fall off very steeply. We explore the implications of this behaviour.