2017/12/31 by S. Sazonov, Sergey Sazonov, Ildar Khabibullin
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Dwarf galaxy #Galaxies: Formation, Evolution, Phenomena #Galaxy #Luminosity #Physics #Population #Star formation #Universe #astro-ph.GA #astro-ph.HE
paper · pdf · doi:10.1093/mnras/sty442
13 pages, 11 figures, accepted for publication in MNRAS
arxiv created 2018/02/02 · openalex publication_date 2018/02/19 · arxiv updated 2018/03/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
In the local Universe, integrated X-ray emission from high-mass X-ray binaries (HMXBs) is dominated by the brightest ultraluminous X-ray sources (ULXs) with luminosity ≳1040 erg s−1. Such rare objects probably also dominated the production of X-rays in the early Universe. We demonstrate that a ULX with LX ∼ 1040–1041 erg s−1 (isotropic-equivalent luminosity in the 0.1–10 keV energy band) shining for ∼105 yr (the expected duration of a supercritically accreting phase in HMXBs) can significantly ionize the ISM in its host dwarf galaxy of total mass M ∼ 107–108 M⊙ and thereby reduce its opacity to soft X-rays. As a result, the fraction of the soft X-ray (below 1 keV) radiation from the ULX escaping into the intergalactic medium (IGM) can increase from ∼20–50 per cent to ∼30–80 per cent over its lifetime. This implies that HMXBs can induce a stronger heating of the IGM at z ≳ 10 compared to estimates neglecting the ULX feedback on the ISM. However, larger galaxies with M ≳ 3 × 108 M⊙ could not be significantly ionized even by the brightest ULXs in the early Universe. Since such galaxies probably started to dominate the global star formation rate at z ≲ 10, the overall escape fraction of soft X-rays from the HMXB population probably remained low, ≲30 per cent, at these epochs.