Probing the star-forming environment of GRB across cosmic ages with high-resolution X-ray spectroscopy: From \textit{XMM-Newton}/RGS and \textit{XRISM}/Resolve to \textit{NewAthena}/X-IFU
Abstract
Optical and infrared GRB absorption spectroscopy provides valuable insight into host-galaxy properties across cosmic time. However, the star-forming region embedding the progenitor, on scales ≲ 100 pc is heavily ionized by the GRB emission, making X-ray spectroscopy the sole probe of its physical and chemical conditions. We characterize the GRB-embedding medium as a function of progenitor type and cosmic epoch via high-resolution X-ray spectroscopy. We extend our study to high-redshift GRBs to evaluate how effectively X-ray absorption signatures can distinguish between pristine, Pop~III-, and Pop~II-enriched environments. Using the time-dependent photoionization code \texttt{TEPID}, we self-consistently calculate the ionization structure of the absorber, the energies and the strengths of the resulting absorption lines. We analyze a flux-selected sample of GRBs showing strong evidence for time-dependent photoionization, and search for predicted narrow features in the RGS spectra. We also assess the performance of \textit{XRISM}/Resolve and \textit{NewAthena}/X-IFU in detecting these features. In the single archival case with sufficient RGS signal-to-noise ratio (GRB~090618 at z=0.54), we find ≈ 3σ combined evidence for narrow, highly ionized Fe~L absorption lines. For bright nearby GRBs, \textit{XRISM}/Resolve can detect Fe~K absorption lines even in its current gate-valve-closed configuration (∼ 3 expected events/yr). \textit{NewAthena}/X-IFU will enable systematic population studies of GRB environments, delivering redshifts with precision comparable to optical/IR spectroscopy, unaffected by dust obscuration and Ly-α forest absorption. Crucially, it will precisely diagnose the density, size, metallicity, and abundance patterns, ultimately revealing whether high-z GRBs originate in pristine, Pop~III-, or Pop~II-enriched media.
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BibTeX
@misc{piro2026probing,
title = {{Probing the star-forming environment of GRB across cosmic ages with high-resolution X-ray spectroscopy: From \textitXMM-Newton/RGS and \textitXRISM/Resolve to \textitNewAthena/X-IFU}},
author = {Luigi Piro and Aishwarya Linesh Thakur and Alfredo Luminari and Fabrizio Nicastro and Yair Krongold},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.32786},
eprint = {2610.32786},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.32786},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Probing the star-forming environment of GRB across cosmic ages with high-resolution X-ray spectroscopy: From \textit{XMM-Newton}/RGS and \textit{XRISM}/Resolve to \textit{NewAthena}/X-IFU
AU - Luigi Piro
AU - Aishwarya Linesh Thakur
AU - Alfredo Luminari
AU - Fabrizio Nicastro
AU - Yair Krongold
PY - 2026
DA - 2026/10/23
PB - arXiv
DO - 10.48550/arxiv.2610.32786
UR - https://arxiv.org/abs/2610.32786
AB - Optical and infrared GRB absorption spectroscopy provides valuable insight into host-galaxy properties across cosmic time. However, the star-forming region embedding the progenitor, on scales ≲ 100 pc is heavily ionized by the GRB emission, making X-ray spectroscopy the sole probe of its physical and chemical conditions. We characterize the GRB-embedding medium as a function of progenitor type and cosmic epoch via high-resolution X-ray spectroscopy. We extend our study to high-redshift GRBs to evaluate how effectively X-ray absorption signatures can distinguish between pristine, Pop~III-, and Pop~II-enriched environments. Using the time-dependent photoionization code \texttt{TEPID}, we self-consistently calculate the ionization structure of the absorber, the energies and the strengths of the resulting absorption lines. We analyze a flux-selected sample of GRBs showing strong evidence for time-dependent photoionization, and search for predicted narrow features in the RGS spectra. We also assess the performance of \textit{XRISM}/Resolve and \textit{NewAthena}/X-IFU in detecting these features. In the single archival case with sufficient RGS signal-to-noise ratio (GRB~090618 at z=0.54), we find ≈ 3σ combined evidence for narrow, highly ionized Fe~L absorption lines. For bright nearby GRBs, \textit{XRISM}/Resolve can detect Fe~K absorption lines even in its current gate-valve-closed configuration (∼ 3 expected events/yr). \textit{NewAthena}/X-IFU will enable systematic population studies of GRB environments, delivering redshifts with precision comparable to optical/IR spectroscopy, unaffected by dust obscuration and Ly-α forest absorption. Crucially, it will precisely diagnose the density, size, metallicity, and abundance patterns, ultimately revealing whether high-z GRBs originate in pristine, Pop~III-, or Pop~II-enriched media.
ER -