Gamma-rays from Type Ia supernova SN2014J

TL;DR

This study analyzes INTEGRAL gamma-ray observations of supernova SN2014J, detecting key radioactive decay lines, comparing results with models, and suggesting symmetric ejecta distribution based on spectral data.

Contribution

First detailed gamma-ray spectral analysis of SN2014J covering 19-162 days, confirming consistency with standard supernova models and providing insights into ejecta symmetry.

Findings

Detection of $^{56}$Co lines at 847 and 1248 keV with >4 sigma significance

Gamma-ray spectra align with delayed detonation or deflagration models

Optical spectra indicate symmetric distribution of radioactive elements

Abstract

The whole set of INTEGRAL observations of type Ia supernova SN2014J, covering the period 19-162 days after the explosion has being analyzed. For spectral fitting the data are split into "early" and "late" periods covering days 19-35 and 50-162, respectively, optimized for $^{56}$Ni and $^{56}$Co lines. As expected for the early period much of the gamma-ray signal is confined to energies below $\sim$200 keV, while for the late period it is most strong above 400 keV. In particular, in the late period $^{56}$Co lines at 847 and 1248 keV are detected at 4.7 and 4.3 $\sigma$ respectively. The lightcurves in several representative energy bands are calculated for the entire period. The resulting spectra and lightcurves are compared with a subset of models. We confirm our previous finding that the gamma-ray data are broadly consistent with the expectations for canonical 1D models, such as delayed detonation or deflagration models for a near-Chandrasekhar mass WD. Late optical spectra (day 136 after the explosion) show rather symmetric Co and Fe lines profiles, suggesting that unless the viewing angle is special, the distribution of radioactive elements is symmetric in the ejecta.