Cool X-ray emitting gas in the core of the Centaurus cluster of galaxies

TL;DR

This study uses deep X-ray spectroscopy to detect and analyze cool X-ray emitting gas in the core of the Centaurus galaxy cluster, revealing detailed temperature, metallicity, and mass deposition characteristics.

Contribution

First detection of Fe-XVII emission at multiple wavelengths in the cluster core, providing new insights into the temperature and metallicity distribution of the X-ray emitting gas.

Findings

Presence of cool gas at 0.3-0.45 keV in the core

Supersolar nitrogen abundance in the central regions

Mass deposition rates of 1.6-3 solar masses per year

Abstract

We use a deep XMM-Newton Reflection Grating Spectrometer observation to examine the X-ray emission from the core of the Centaurus cluster of galaxies. We clearly detect Fe-XVII emission at four separate wavelengths, indicating the presence of cool X-ray emitting gas in the core of the cluster. Fe ions from Fe-XVII to XXIV are observed. The ratio of the Fe-XVII 17.1A lines to 15.0A line and limits on O-VII emission indicate a lowest detected temperature in the emitting region of 0.3 to 0.45 keV (3.5 to 5.2x10^6 K). The cluster also exhibits strong N-VII emission, making it apparent that the N abundance is supersolar in its very central regions. Comparison of the strength of the Fe-XVII lines with a Solar metallicity cooling flow model in the inner 17 kpc radius gives mass deposition rates in the absence of heating of 1.6-3 Msun/yr. Spectral fitting implies an upper limit of 0.8 Msun/yr below 0.4 keV, 4 Msun/yr below 0.8 keV and 8 Msun/yr below 1.6 keV. The cluster contains X-ray emitting gas over at least the range of 0.35 to 3.7 keV, a factor of more than 10 in temperature. We find that the best fitting metallicity of the cooler components is smaller than the hotter ones, confirming that the apparent metallicity does decline within the inner 1 arcmin radius.