On the influence of shock-cloud interactions on the nonthermal X-ray emission from the supernova remnant RCW 86

TL;DR

This study investigates how shock-cloud interactions in supernova remnant RCW 86 influence nonthermal X-ray emissions, revealing that cloud interactions decelerate shocks and alter thermal and synchrotron X-ray properties, with implications for cosmic-ray acceleration.

Contribution

It provides spatially resolved X-ray spectroscopy evidence showing the impact of shock-cloud interactions on X-ray emission and shock dynamics in RCW 86, highlighting differences from other remnants.

Findings

Shock deceleration due to cloud interaction enhances thermal X-ray emission.

Synchrotron X-ray emission is softer and fainter near dense clouds.

Differences in X-ray properties among remnants may be due to cloud clumpiness.

Abstract

It is an open issue how the surrounding environment of supernova remnant shocks affect nonthermal X-rays from accelerated electrons, with or without interacting dense material. We have conducted spatially resolved X-ray spectroscopy of the shock-cloud interacting region of RCW 86 with XMM-Newton. It is found that bright soft X-ray filaments surround the dense cloud observed with 12CO and HI emission lines. These filaments are brighter in thermal X-ray emission, and fainter and possibly softer in synchrotron X-rays, compared to those without interaction. Our results show that the shock decelerates due to the interaction with clouds, which results in an enhancements of thermal X-ray emission. This could possibly also explain the softer X-ray synchrotron component, because it implies that those shocks that move through a low density environment, and therefore decelerate much less, can be more efficient accelerators. This is similar to SN 1006 and Tycho, and is in contrast to RX J1713.7-3946. This difference among remnants may be due to the clumpiness of dense material interacting with the shock, which should be examined with future observations.