Population III X-ray binaries and their impact on the early universe. Issue 3 (10th March 2023)

• Record Type: Journal Article
• Authors: Sartorio, Nina S; Fialkov, A; Hartwig, T; Mirouh, G M; Izzard, R G; Magg, M; Klessen, R S; Glover, S C O; Chen, L; Tarumi, Y; Hendriks, D D
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 521:Issue 3(2023)
• Page Start: 4039
• Page End: 4055
• Publication Date: 2023-03-10
• Subjects: stars: Population III -- (cosmology:) diffuse radiation -- X-rays: binaries -- (cosmology:) early Universe; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stad697
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: The first population of X-ray binaries (XRBs) is expected to affect the thermal and ionization states of the gas in the early Universe. Although these X-ray sources are predicted to have important implications for high-redshift observable signals, such as the hydrogen 21-cm signal from cosmic dawn and the cosmic X-ray background, their properties are poorly explored, leaving theoretical models largely uninformed. In this paper we model a population of X-ray binaries arising from zero metallicity stars. We explore how their properties depend on the adopted initial mass function (IMF) of primordial stars, finding a strong effect on their number and X-ray production efficiency. We also present scaling relations between XRBs and their X-ray emission with the local star formation rate, which can be used in sub-grid models in numerical simulations to improve the X-ray feedback prescriptions. Specifically, we find that the uniformity and strength of the X-ray feedback in the intergalactic medium is strongly dependant on the IMF. Bottom-heavy IMFs result in a smoother distribution of XRBs, but have a luminosity orders of magnitude lower than more top-heavy IMFs. Top-heavy IMFs lead to more spatially uneven, albeit strong, X-ray emission. An intermediate IMF has a strong X-ray feedback while sustaining an even emission across the intergalactic medium. These differences in X-ray feedback could be probed in the future with measurements of the cosmic dawn 21-cm line of neutral hydrogen, which offers us a new way of constraining population III IMF.