Preheating of the early universe by radiation from high-mass X-ray binaries
Abstract
Using a reliablymeasured intrinsic (i.e., corrected for absorption effects) present-day luminosity function of high-mass X-ray binaries (HMXBs) in the 0.25-2 keV energy band per unit star formation rate, we estimate the preheating of the early Universe by soft X-rays from such systems. We find that X-ray irradiation, mainly executed by ultraluminous and supersoft ultraluminous X-ray sources with luminosity L X > 1039 erg s-1, could significantly heat ( T > T CMB, where T CMB is the temperature of the cosmic microwave background) the intergalactic medium by z 10 if the specific X-ray emissivity of the young stellar population in the early Universe was an order of magnitude higher than at the present epoch (which is possible due to the low metallicity of the first galaxies) and the soft X-ray emission from HMXBs did not suffer strong absorption within their galaxies. This makes it possible to observe the 21 cm line of neutral hydrogen in emission from redshifts z < 10.
- Publication:
-
Astronomy Letters
- Pub Date:
- April 2017
- DOI:
- 10.1134/S1063773717040077
- arXiv:
- arXiv:1612.01262
- Bibcode:
- 2017AstL...43..211S
- Keywords:
-
- early Universe;
- reionization;
- high-mass X-ray binaries;
- ultraluminous X-ray sources;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 9 pages, 4 figures, accepted for publication in Astronomy Letters