X-ray emission from SN 2012ca: A Type Ia-CSM supernova explosion in a dense surrounding medium

Christopher D. Bochenek, Vikram V. Dwarkadas, Jeffrey M. Silverman, Ori D. Fox, Roger A. Chevalier, Nathan Smith, Alexei V. Filippenko

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)336-344
Number of pages9
JournalMonthly Notices of the Royal Astronomical Society
Volume473
Issue number1
DOIs
StatePublished - Jan 1 2018

Keywords

  • Circumstellar matter
  • Shock waves
  • Stars: mass-loss
  • Supernovae: general
  • Supernovae: individual: SN 2012ca
  • X-rays: individual: SN 2012ca

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Bochenek, C. D., Dwarkadas, V. V., Silverman, J. M., Fox, O. D., Chevalier, R. A., Smith, N., & Filippenko, A. V. (2018). X-ray emission from SN 2012ca: A Type Ia-CSM supernova explosion in a dense surrounding medium. Monthly Notices of the Royal Astronomical Society, 473(1), 336-344. https://doi.org/10.1093/MNRAS/STX2029