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arXiv · 2304.14080

X-ray Binaries in External Galaxies

Marat Gilfanov·Giuseppina Fabbiano·Bret Lehmer·Andreas Zezas
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Abstract

X-ray appearance of normal galaxies is mainly determined by X-ray binaries powered by accretion onto a neutron star or a stellar mass black hole. Their populations scale with the star-formation rate and stellar mass of the host galaxy and their X-ray luminosity distributions show a significant split between star-forming and passive galaxies, both facts being consequences of the dichotomy between high- and low-mass X-ray binaries. Metallicity, IMF and stellar age dependencies, and dynamical formation channels add complexity to this picture. The numbers of high-mass X-ray binaries observed in star-forming galaxies indicate quite high probability for a massive star to become an accretion powered X-ray source once upon its lifetime. This explains the unexpectedly high contribution of X-ray binaries to the Cosmic X-ray Background, of the order of $\sim 10\%$, mostly via X-ray emission of faint star-forming galaxies located at moderate redshifts which may account for the unresolved part of the CXB. Cosmological evolution of the $L_X-{\rm SFR}$ relation can make high-mass X-ray binaries a potentially significant factor in (pre)heating of intergalactic medium in the early Universe.

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Marat Gilfanov, Giuseppina Fabbiano, Bret Lehmer, Andreas Zezas. 2023-04-27. X-ray Binaries in External Galaxies. https://doi.org/10.1007/978-981-16-4544-0_108-1

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