Decomposition of galactic X-ray emission with P

Context. X-ray observations of galaxies with high spatial resolution instruments such as Chandra have revealed that major contributions to their diffuse emission originate from X-ray-bright point sources in the galactic stellar field. It has been established that these point sources, called X-ray binaries, are accreting compact objects with stellar donors in a binary configuration. They are classified according to the predominant accretion process: wind-fed in the case of high-mass donors and Roche-lobe mass transfer in the case of low-mass donors. Observationally, it is challenging to reliably disentangle these two populations from each other because of their similar spectra. Aims. We provide a numerical framework with which spatially and spectrally accurate representations of X-ray binary populations can be studied from hydrodynamical cosmological simulations. We construct average spectra, accounting for a hot gas component, and verify the emergence of observed scaling relations between galaxy-wide X-ray luminosity (LX) and stellar mass (M*) and between LX and the star-formation rate (SFR). Methods. Using simulated galaxy halos extracted from the (48 h−1 cMpc)3 volume of the Magneticum Pathfinder cosmological simulations at z = 0.07, we generate mock spectra with the X-ray photon-simulator PHO