Luminosity function and collective spectrum of bright high-mass X-ray binaries, implications for cosmic X-ray preheating
Abstract
Based on a sample of 200 Chandra sources in 27 nearby galaxies and star formation rate and ISM maps for these galaxies, we have constructed the intrinsic, SFR-normalized X-ray luminosity function and collective X-ray spectrum of luminous HMXBs in the local Universe. The integrated HMXB emission is dominated by ultraluminous X-ray sources, with hard ones (those with the 0.25-2/0.25-8 keV flux ratio <0.6) dominating above 2 keV and soft and supersoft ones (with hardness ratios 0.6-0.95 and >0.95, respectively) at lower energies. The derived collective spectrum probably represents the angle-averaged X-ray emission of near- and super-critically accreting stellar mass black holes and neutron stars in the local Universe and provides an important constraint on supercritical accretion models. This local statistics suggest that ULXs and supersoft ULXs could significantly heat the Universe by z∼ 10 if the specific X-ray emissivity of the young stellar population at that epoch was an order of magnitude higher than at the present epoch.
- Publication:
-
The X-ray Universe 2017
- Pub Date:
- October 2017
- Bibcode:
- 2017xru..conf..204S