Neutral fraction of hydrogen in the intergalactic medium surrounding high-redshift gamma-ray burst 210905A

ABSTRACT The Epoch of Reionization (EoR) is a key period of cosmological history in which the intergalactic medium (IGM) underwent a major phase change from being neutral to almost completely ionized. Gamma-ray bursts (GRBs) are luminous and unique probes of their environments that can be used to study the timeline for the progression of the EoR. Here, we present a detailed analysis of the European Southern Observatory Very Large Telescope X-shooter spectrum of GRB 210905A, which resides at a redshift of $z\sim 6.3$. We focus on estimating the fraction of neutral hydrogen, $x_{\rm H \, {\small I}}$, on the line of sight to the host galaxy of GRB 210905A by fitting the shape of the Lyman-$\alpha$ damping wing of the afterglow spectrum. The X-shooter spectrum has a high signal-to-noise ratio, but the complex velocity structure of the host galaxy limits the precision of our conclusions. The statistically preferred model suggests a low neutral fraction with a 3$\sigma$ upper limit of $x_{\rm H \, {\small I}} \lesssim 0.15$ or $x_{\rm H \, {\small I}} \lesssim 0.23$, depending on the absence or presence of an ionized bubble around the GRB host galaxy, indicating that the IGM around the GRB host galaxy is mostly ionized. We discuss complications in current analyses and potential avenues for future studies of the progression of the EoR and its evolution with redshift.

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Publication Details

Journal
Monthly Notices of the Royal Astronomical Society
Published
2024-12-16
DOI
https://doi.org/10.1093/mnras/stae2757
Citations
4
Primary Topic
Gamma-ray bursts and supernovae
Type
article
Field-Weighted Citation Impact
1.33

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article

Neutral fraction of hydrogen in the intergalactic medium surrounding high-redshift gamma-ray burst 210905A

K. Wiersema, A. Melandri, P. Jakobsson, J. T. Palmerio et al.
4 citations
Monthly Notices of the Royal Astronomical Society
Gamma-ray bursts and supernovae
1.33
article

Neutral fraction of hydrogen in the intergalactic medium surrounding high-redshift gamma-ray burst 210905A

K. Wiersema, A. Melandri, P. Jakobsson, J. T. Palmerio, C. Kouveliotou, H. Fausey, G. Pugliese, A. J. Levan, A. Martín-Carrillo, J. P. U. Fynbo, S. Vejlgaard, M. de Pasquale, D. Malesani, V. D’Elia, N. R. Tanvir, A. J. van der Horst, A. Rossi, D. H. Hartmann, S. Covino, Luca Izzo, R. Salvaterra, A. Saccardi, S. Campana, K. E. Heintz, S. D. Vergani
article en
4 citations

Abstract

ABSTRACT The Epoch of Reionization (EoR) is a key period of cosmological history in which the intergalactic medium (IGM) underwent a major phase change from being neutral to almost completely ionized. Gamma-ray bursts (GRBs) are luminous and unique probes of their environments that can be used to study the timeline for the progression of the EoR. Here, we present a detailed analysis of the European Southern Observatory Very Large Telescope X-shooter spectrum of GRB 210905A, which resides at a redshift of $z\sim 6.3$. We focus on estimating the fraction of neutral hydrogen, $x_{\rm H \, {\small I}}$, on the line of sight to the host galaxy of GRB 210905A by fitting the shape of the Lyman-$\alpha$ damping wing of the afterglow spectrum. The X-shooter spectrum has a high signal-to-noise ratio, but the complex velocity structure of the host galaxy limits the precision of our conclusions. The statistically preferred model suggests a low neutral fraction with a 3$\sigma$ upper limit of $x_{\rm H \, {\small I}} \lesssim 0.15$ or $x_{\rm H \, {\small I}} \lesssim 0.23$, depending on the absence or presence of an ionized bubble around the GRB host galaxy, indicating that the IGM around the GRB host galaxy is mostly ionized. We discuss complications in current analyses and potential avenues for future studies of the progression of the EoR and its evolution with redshift.

Monthly Notices of the Royal Astronomical SocietyVol. 536(3)
University College Dublin (IE), University of Messina (IT), University of Copenhagen (DK), Centre National de la Recherche Scientifique (FR), University of Hertfordshire (GB), Radboud University Nijmegen (NL), University of Leicester (GB), University of Iceland (IS), George Washington University (US), Université Paris Sciences et Lettres (FR), Astronomical Observatory of Rome (IT), Agenzia Spaziale Italiana (IT), Institut d'Astrophysique de Paris (FR), Brera Astronomical Observatory (IT), University of Warwick (GB), Galaxies, Etoiles, Physique et Instrumentation (FR), Istituto di Astrofisica Spaziale e Fisica Cosmica di Milano (IT), DAWN Center for Independent Living (US), Janssen (Switzerland) (CH), Astronomical Institute of the Slovak Academy of Sciences (SK), Azienda Ospedaliera Ospedali Riuniti Papardo Piemonte (IT), Lancaster University (GB), Clemson University (US), National Institute for Astrophysics (IT), University of Amsterdam (NL)
University of Leicester, Ministero dell’Istruzione, dell’Università e della Ricerca, European Southern Observatory
Openalex Percentile: Top 21%
Gamma-ray bursts and supernovae
1.33
DOIOpen Access PDFOpenAlex
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