What's important at z>5? X-ray Emission from Starbursts!
Abstract
There has recently been quite a bit of excitement on the role of X-ray emission from galaxies in reionization. It turns out that the X-ray output from X-ray binaries and hot gas are both likely important and may rival the ionizing output of AGN at z>5, particularly for Hydrogen reionization. Here we present our research on constraining the X-ray SED of high-redshift galaxies using an important local universe analog population, the Lyman Break Galaxy Analogs. We have established a relationship between the 2-10 keV X-ray luminosity, assumed to originate from X-ray binaries (XRBs), and star formation rate (SFR) in rest-frame UV-selected galaxies across cosmic time -- ranging from Lyman break galaxies (LBGs) in the early Universe (z=1.5-4) to Lyman break analogs (LBAs) in the present-day Universe ( 0.1). We present results from the 4Ms Chandra Deep Field South (CDF-S) observations of ~4000 z=1.5-4 LBGs as well as in-depth studies of a sample of six nearby GALEX-selected 0.1 LBAs, which are individually X-ray detected. Both populations may yield a larger output in collective HMXB luminosity per unit SFR than that observed in local (z=0) star-forming galaxies. We also discuss the properties of the hot gas in these galaxies, particularly what we hope to learn with next generation facilities such as the Athena calorimeter.
- Publication:
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AAS/High Energy Astrophysics Division #14
- Pub Date:
- August 2014
- Bibcode:
- 2014HEAD...1411012H