Thermal and Non-thermal X-Rays from the Galactic Supernova Remnant G348.5+0.1

TL;DR

This study analyzes Suzaku X-ray observations of the supernova remnant G348.5+0.1, revealing a recombining plasma in the thermal region and non-thermal emission likely from a pulsar wind nebula, indicating complex plasma evolution.

Contribution

First identification of a recombining plasma in G348.5+0.1, providing insights into plasma cooling processes in supernova remnants.

Findings

Recombination-dominant plasma fits the thermal X-ray spectrum.

Non-thermal X-rays are consistent with a pulsar wind nebula.

Both thermal and non-thermal emissions are associated with the same SNR.

Abstract

We report on Suzaku results of the two distinct regions in the Galactic supernova remnant G348.5+0.1: extended thermal X-rays ("soft diffuse") at the northeast region and non-thermal X-rays (CXOU J171419.8-383023) at the northwest region. The X-ray spectrum of the soft diffuse is fitted with neither an ionization equilibrium nor a non-equilibrium (ionizing) plasma model, leaving saw-teeth residuals in the 1.5-3 keV energy band. The residual structures can be produced when free electrons are recombined to the K-shells of highly ionized Mg and Si ions. In fact, the X-ray spectrum is nicely fitted with a recombination-dominant plasma model. We propose a scenario that the plasma in nearly full ionized state at high temperature quickly changed to a recombining phase due to selective cooling of electrons to a lower temperature of ~0.5 keV. The spectrum of CXOU J171419.8-383023 is well explained by a simple power-law model with a photon index of 1.9, nearly equal to the typical value of pulsar wind nebulae. Since the distance is estimated to be the same as that of the soft diffuse, we infer that both the soft diffuse and CXOU J171419.8-383023 are associated with the same object, SNR G348.5+0.1.