2018MNRAS.473..336B -
Mon. Not. R. Astron. Soc., 473, 336-344 (2018/January-1)
X-ray emission from SN 2012ca: A Type Ia-CSM supernova explosion in a dense surrounding medium.
BOCHENEK C.D., DWARKADAS V.V., SILVERMAN J.M., FOX O.D., CHEVALIER R.A., SMITH N. and FILIPPENKO A.V.
Abstract (from CDS):
X-ray emission is one of the signposts of circumstellar interaction in supernovae (SNe), but until now, it has been observed only in core-collapse SNe. The level of thermal X-ray emission is a direct measure of the density of the circumstellar medium (CSM), and the absence of X-ray emission from Type Ia SNe has been interpreted as a sign of a very low density CSM. In this paper, we report late-time (500-800 d after discovery) X-ray detections of SN 2012ca in Chandra data. The presence of hydrogen in the initial spectrum led to a classification of Type Ia-CSM, ostensibly making it the first SN Ia detected with X-rays. Our analysis of the X-ray data favours an asymmetric medium, with a high-density component which supplies the X-ray emission. The data suggest a number density >108 cm–3 in the higher density medium, which is consistent with the large observed Balmer decrement if it arises from collisional excitation. This is high compared to most core-collapse SNe, but it may be consistent with densities suggested for some Type IIn or superluminous SNe. If SN 2012ca is a thermonuclear SN, the large CSM density could imply clumps in the wind, or a dense torus or disc, consistent with the single-degenerate channel. A remote possibility for a core-degenerate channel involves a white dwarf merging with the degenerate core of an asymptotic giant branch star shortly before the explosion, leading to a common envelope around the SN.
Abstract Copyright:
© 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
Journal keyword(s):
shock waves - circumstellar matter - stars: mass-loss - supernovae: general - supernovae: individual: SN 2012ca - X-rays: individual: SN 2012ca - X-rays: individual: SN 2012ca
Simbad objects:
20
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