Studying the Supernova Remnant G31.9+0.0 in Gamma and X-Rays

TL;DR

This study analyzes gamma-ray and X-ray data of supernova remnant G31.9+0.0 (3C 391), revealing plasma properties and confirming gamma-ray detection with detailed spectral analysis, contributing to understanding its emission mechanisms.

Contribution

First combined X-ray and gamma-ray analysis of G31.9+0.0, providing detailed plasma parameters and gamma-ray spectral characterization, advancing knowledge of supernova remnant emission.

Findings

X-ray plasma in ionization equilibrium with kTe ~ 0.57 keV

Gamma-ray detection at ~13 sigma significance

Gamma-ray spectrum fitted with a log-parabola with specific parameters

Abstract

G31.9+0.0 (3C 391) is a Galactic mixed-morphology supernova remnant observed in GeV gamma rays by Fermi Gamma Ray Space Telescope's LAT (Fermi-LAT), as well as in the 0.3-10 keV X-ray band by Suzaku. In this paper, we will present the analysis results of X- and gamma-ray data of 3C 391 taken with Suzaku and Fermi-LAT. The X-ray spectrum of 3C 391 was fitted to a single-temperature variable abundance non-equilibrium ionization model with an electron temperature of kTe ~ 0.57 keV, an absorbing column density of NH ~ 3.1 x 10^{22} cm^{-2} and a very high ionization age (\tau > 10^{12} cm^{-3} s), which suggest that the plasma has reached ionization equilibrium. The spectrum shows clearly detected emission lines of Mg, Si, and S. 3C 391 was detected in GeV gamma rays with a significance of ~ 13 sigma. The spectrum was fitted with a log-parabola function, where the spectral index and beta parameters were found to be \alpha = 2.35 +- 0.07 and \beta = 0.366 +- 0.339. The integrated flux above 200 MeV was found as F = (2.34 +- 0.37) x 10^{-8} ph cm^{-2} s^{-1}. These results are in agreement with the Fermi-LAT results given in the 2nd Fermi-LAT catalog.