The origin of the X-ray emitting plasma in the eastern edge of the Cygnus Loop

TL;DR

This study investigates the origin of bright X-ray emission at the Cygnus Loop's eastern edge, emphasizing the role of thermal conduction in shock-cloud interactions through spectral analysis of XMM-Newton data.

Contribution

It provides new insights into the physical processes, especially thermal conduction, influencing X-ray emission in the complex environment of the Cygnus Loop's eastern edge.

Findings

Inhomogeneous cavity wall contains large and small clumps with different densities.

Thermal conduction plays a significant role in the evolution of X-ray emitting plasma.

ISM abundance around the region is approximately 0.2 times solar.

Abstract

The Cygnus Loop is interacting with a protrusion of the cavity wall in its eastern edge (the XA region), where the X-ray emission is very bright. The complexity of the environment and the non-linear physical processes of the shock-cloud interaction make the origin of the X-ray emission still not well understood. Our purpose is to understand the physical origin of the X-ray emission in the XA region, addressing, in particular, the role of thermal conduction in the interaction process. We analyzed two XMM-Newton data sets, performing image analysis and spatially resolved spectral analysis on a set of homogeneous regions. We applied a recently developed diagnostic tool to compare spectral analysis results with predictions of theoretical models, and to estimate the efficiency of thermal conduction on the X-ray emitting shocked plasma. We found that the inhomogeneous cavity wall contains both large clumps (the protrusion) and small isolated clumps with different densities. A large indentation bent over to the south is detected. The abundance of the surrounding ISM is ~0.2 times solar value. We confirmed the important role of thermal conduction in the evolution of X-ray emitting plasma during shock-cloud interaction.