English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Massive stars at redshifts z > 6 are predicted to have played a pivotal rolein cosmological reionization as luminous sources of ultra-violet (UV) photons.However, the remnants of these massive stars could be equally important asX-ray luminous (L_X 1e38 erg/s) high-mass X-ray binaries (HMXBs). Because theabsorption cross section of neutral hydrogen decreases sharply with photonenergy (proportional to the inverse cube), X-rays can escape more freely thanUV photons from the star-forming regions in which they are produced, allowingHMXBs to make a potentially significant contribution to the ionizing X-raybackground during reionization. In this paper, we explore the ionizing power ofHMXBs at redshifts z > 6 using a Monte Carlo model for a coeval stellarpopulation of main sequence stars and HMXBs. Using the archetypal Galactic HMXBCygnus X-1 as our template, we propose a composite HMXB spectral energydistribution consisting of black-body and power-law components, whosecontributions depend on the accretion state of the system. We determine thetime-dependent ionizing power of a combined population of UV-luminous stars andX-ray luminous HMXBs, and deduce fitting formulae for the boost in thepopulation's ionizing power arising from HMXBs; these fits allow for simpleimplementation of HMXB feedback in numerical simulations. Based on thisanalysis, we estimate the contribution of high redshift HMXBs to thepresent-day soft X-ray background, and we show that it is a factor of ~100-1000smaller than the observed limit. Finally, we discuss the implications of ourresults for the role of HMXBs in reionization and in high redshift galaxyformation.

Feedback from High-Mass X-Ray Binaries on the High Redshift Intergalactic Medium : Model Spectra