Speaker
Description
Surveys of the extragalactic Universe, from ultraviolet to infrared
wavelengths, have been extremely effective at piecing together a basic picture
of how stars in galaxies evolved throughout cosmic history. At X-ray
wavelengths, normal-galaxy emission (i.e., not due to AGN) is dominated by hot
gas and populations of X-ray binaries (XRBs). eROSITA is expected to detect
~10,000 normal galaxies in X-rays, much larger than the populations of 100s of
normal galaxies that are currently studied in X-ray surveys. In this talk, I
will review recent efforts to establish an empirical framework that
characterizes how the X-ray emission from normal-galaxy populations varies with
galaxy properties like star-formation history and metallicity. I will present
estimates of how the X-ray emission from galaxies likely evolved over cosmic
time in response to changes in galaxy star-formation activity and metallicity.
I will show that X-ray emissivity of the Universe at z > 4-6 is expected to be
dominated by normal-galaxy populations and could provide significant heating of
the early intergalactic medium (IGM) before the epoch of reionization in the
Universe. Finally, I will discuss how eROSITA will help to fill important
knowledge gaps in our empirical framework, and provide broader new insight into
galaxy evolution and the X-ray radiation field of the early IGM.
