The Metallicity Dependence of the High-Mass X-ray Binary Luminosity Function

Understand

We present detailed constraints on the metallicity dependence of the high mass X-ray binary (HMXB) X-ray luminosity function (XLF).

• We analyze ~5 Ms of Chandra data for 55 actively star-forming galaxies at D < 30 Mpc with gas-phase metallicities spanning 12 + log(O/H) = 7-9.2.
• Within the galactic footprints, our sample contains a total of 1311 X-ray point sources, of which ~49% are expected to be HMXBs, with the remaining sources likely to be low-mass X-ray binaries (LMXBs; ~22%) and unrelated background sources (~29%).
• We construct a model that successfully characterizes the average HMXB XLF over the full metallicity range.