Discovery of a Pair of Galaxies with Both Hosting X-Ray Binary Candidates at z = 2.544
Year: 2025
Type: article
Abstract: Among high-redshift galaxies, aside from active galactic nuclei (AGNs), X-ray binaries (XRBs) can be significant sources of X-ray emission. XRBs play a crucial role in galaxy evolution, reflecting the stellar populations of galaxies and regulating star formation through feedback, thereby shaping galaxy structure. In this study, we report a spectroscopically confirmed X-ray emitting galaxy pair (UDF3 and UDF3-2) at z = 2.544. By combining multiwavelength observations from JWST/NIRSpec Micro-Shutter Assembly spectra, JWST/NIRCam and MIRI imaging, Chandra, Hubble Space Telescope, Very Large Telescope, Atacama Large Millimeter/submillimeter Array, and Very Large Array, we analyze the ionized emission lines, which are primarily driven by H II region–like processes. Additionally, we find that the mid-infrared radiation can be fully attributed to dust emission from the galaxies themselves. Our results indicate that the X-ray emission from these two galaxies is dominated by high-mass XRBs, with luminosities of L X = (1.43 ± 0.40) × 10 42 erg s −1 for UDF3 and (0.40 ± 0.12) × 10 42 erg s −1 for UDF3-2. Furthermore, we measure the star formation rate (SFR) of 52 9 − 88 + 64 M ⊙ yr −1 for UDF3, placing it ≈0.5 dex below the L X /SFR– z relation. This offset reflects the redshift-dependent enhancement of L X /SFR– z relation, which is influenced by metallicity and serves as a key observable for XRB evolution. In contrast, UDF3-2, with an SFR of 3 4 − 6 + 6 M ⊙ yr −1 , aligns well with the L X /SFR– z relation. This galaxy pair represents the highest redshift non-AGN-dominated galaxies with individual X-ray detections reported to date. This finding suggests that the contribution of XRBs to galaxy X-ray emission at high redshift may be underestimated.
Authors: Sijia Cai, Zheng Cai, Jianwei Lyu, Yunjing Wu, Xiaojing Lin, Mingyu Li, Junjie Mao, Jiayi Chen, Pengjun Lu
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,400
OpenAlex ID: W6947629508
FWCI:
Cites:
Cited by:
Related to: