SFHs of GOODS z=0-3.5 gal. with X-ray em.

Scaling relations of normal-galaxy X-ray luminosity (L_X_) with star formation rate (SFR) and stellar mass (M_*_) have been used to show that the formation rates of low-mass and high-mass X-ray binaries (LMXBs and HMXBs, respectively) evolve with redshift across z~0-2 following L_HMXB_/SFR{propto}(1+z) and L_LMXB_/M*{propto}(1+z)^2-3^.

However, these measurements alone do not directly reveal the physical mechanisms behind the redshift evolution of X-ray binaries (XRBs). We derive star formation histories for a sample of 344 normal galaxies in the CDFs, using spectral energy distribution (SED) fitting of FUV-to-FIR photometric data, and construct a self-consistent, age-dependent model of the X-ray emission from the galaxies. Our model quantifies how X-ray emission from hot gas and XRB populations vary as functions of host stellar-population age.