Unresolved and diffuse components of X-ray emission and X/K luminosity ratios in nearby early-type and late-type galaxies

Understand

We explore the nature of unresolved X-ray emission in a broad sample of galaxies of all morphological types based on archival Chandra data.

• After removing bright compact sources, we study L_X/L_K luminosity ratios of unresolved emission, and compare them with the Solar neighborhood values.
• We conclude that unresolved emission is determined by four main components, three of which were known before: (i) The population of faint unresolved sources associated with old stellar population.
• In early-type galaxies, their 2-10 keV band luminosity scales with the stellar mass with L_X/L_K = (3.1\pm 0.9) x 10^27 erg/s/L_K,sun; (ii) The ISM with kT ~ 0.2-0.8 keV present in galaxies of all types.