The Chandra Carina Complex Project: Deciphering the Enigma of Carina's Diffuse X-ray Emission

TL;DR

This study uses Chandra X-ray data to analyze the diffuse X-ray emission in the Carina Nebula, revealing that most of it is truly diffuse and likely generated by charge exchange at plasma interfaces.

Contribution

It provides a detailed spectral analysis of Carina's diffuse X-ray emission, demonstrating that unresolved emission is predominantly truly diffuse and identifying charge exchange as a key emission mechanism.

Findings

Most unresolved X-ray emission is truly diffuse.

Charge exchange contributes significantly to the X-ray emission.

Spectral residuals indicate plasma interactions at cold-hot interfaces.

Abstract

We present a 1.42 square degree mosaic of diffuse X-ray emission in the Great Nebula in Carina from the Chandra X-ray Observatory Advanced CCD Imaging Spectrometer camera. After removing >14,000 X-ray point sources from the field, we smooth the remaining unresolved emission, tessellate it into segments of similar apparent surface brightness, and perform X-ray spectral fitting on those tessellates to infer the intrinsic properties of the X-ray-emitting plasma. By modeling faint resolved point sources, we estimate the contribution to the extended X-ray emission from unresolved point sources and show that the vast majority of Carina's unresolved X-ray emission is truly diffuse. Line-like correlated residuals in the X-ray spectral fits suggest that substantial X-ray emission is generated by charge exchange at the interfaces between Carina's hot, rarefied plasma and its many cold neutral pillars, ridges, and clumps.