IGM damping wing constraints on the tail end of reionization from the enlarged XQR-30 sample

Journal Article · 22 April 2024 · Monthly Notices of the Royal Astronomical Society

DOI: https://doi.org/10.1093/mnras/stae1080 · OSTI ID:2345076

Greig, B. ; Mesinger, A. ; Bañados, E. ; Becker, G. D.; Bosman, S. E. I. ; Chen, H. ; Davies, F. B. ; D’Odorico, V. ; Eilers, A. -C ; Gallerani, S.; Haehnelt, M. G.; Keating, L. ; Lai, S. ; Qin, Y. ; Ryan-Weber, E.; Satyavolu, S.; Wang, F.; Yang, J.; Zhu, Y.

ABSTRACT The attenuation of Lyα photons by neutral hydrogen in the intergalactic medium (IGM) at z ≳ 5 continues to be a powerful probe for studying the epoch of reionization. Given a framework to estimate the intrinsic (true) Lyα emission of high-z sources, one can infer the ionization state of the IGM during reionization. In this work, we use the enlarged XQR-30 sample of 42 high-resolution and high signal-to-noise quasar spectra between $$5.8\lesssim \, z\lesssim \, 6.6$$ obtained with VLT/X-shooter to place constraints on the IGM neutral fraction. This is achieved using our existing Bayesian QSO reconstruction framework which accounts for uncertainties such as the: (i) posterior distribution of predicted intrinsic Lyα emission profiles (obtained via covariance matrix reconstruction of the Lyα and N v emission lines from unattenuated high-ionization emission line profiles; C iv, Si iv  + O iv], and C iii]) and (ii) distribution of ionized regions within the IGM using synthetic damping wing profiles drawn from a 1.63 Gpc3 reionization simulation. Following careful quality control, we used 23 of the 42 available QSOs to obtain constraints/limits on the IGM neutral fraction during the tail-end of reionization. Our median and 68th percentile constraints on the IGM neutral fraction are: $$0.20\substack{+0.14 -0.12}$$ and $$0.29\substack{+0.14 -0.13}$$ at z = 6.15 and 6.35. Further, we also report 68th percentile upper limits of $$\bar{x}_{\mathrm{H\, {\small I}}{}} \lt 0.21$$, 0.20, 0.21, and 0.18 at z = 5.8, 5.95, 6.05, and 6.55. These results imply reionization is still ongoing at $$5.8\lesssim \, z\lesssim \, 6.55$$, consistent with previous results from XQR-30 (dark fraction and Lyα forest) along with other observational probes considered in the literature.

• Sponsoring Organization: USDOE
• OSTI ID: 2345076
• Journal Information: Monthly Notices of the Royal Astronomical Society, Journal Name: Monthly Notices of the Royal Astronomical Society Journal Issue: 3 Vol. 530; ISSN 0035-8711
• Publisher: Oxford University PressCopyright Statement
• Country of Publication: United Kingdom
• Language: English