Non-thermal emission from supernova shock breakout and the origin of the X-ray transient associated with SN2008D

TL;DR

This paper proposes that non-thermal X-ray emission in supernova shock breakout can result from multiple photon scatterings, explaining the X-ray transient associated with SN2008D as shock breakout emission.

Contribution

It introduces a bulk-Comptonization mechanism for non-thermal emission in supernova shock breakout, providing a new explanation for observed X-ray transients.

Findings

Non-thermal spectra can form via multiple scatterings in shock breakout.

SN2008D's X-ray transient is consistent with shock breakout emission.

Bulk-Comptonization significantly alters thermal photon spectra.

Abstract

We suggest that non-thermal emission can be produced by multiple scatterings of the photons between the supernova ejecta and pre-shock material in supernova shock breakout. Such bulk-Comptonization process may significantly change the original thermal photon spectrum, forming a power-law non-thermal component at higher energies. We then show that the luminous X-ray outburst XRO081009 associated with SN2008D is likely to be such shock breakout emission from an ordinary type Ib/c supernova.