Using Ly$α$ Transmitted Spectrum to Probe IGM Transmission and Identify Ionized Structures in Cosmic Reionization

Fuente: arXiv
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Auteurs principaux: Hu, Weida, Papovich, Casey, Shen, Lu, Haro, Pablo Arrabal, Backhaus, Bren E., Cleri, Nikko J., Dickinson, Mark, Dunlop, James S., Finkelstein, Steven L., Giavalisco, Mauro, Koekemoer, Anton M., Kokorev, Vasily, Mascia, Sara, Napolitano, Lorenzo, Pentericci, Laura, Smith, Aaron, Taylor, Anthony J., Wang, Xin, Yung, L. Y. Aaron
Format: Preprint
Publié: 2026
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author Hu, Weida
Papovich, Casey
Shen, Lu
Haro, Pablo Arrabal
Backhaus, Bren E.
Cleri, Nikko J.
Dickinson, Mark
Dunlop, James S.
Finkelstein, Steven L.
Giavalisco, Mauro
Koekemoer, Anton M.
Kokorev, Vasily
Mascia, Sara
Napolitano, Lorenzo
Pentericci, Laura
Smith, Aaron
Taylor, Anthony J.
Wang, Xin
Yung, L. Y. Aaron
author_facet Hu, Weida
Papovich, Casey
Shen, Lu
Haro, Pablo Arrabal
Backhaus, Bren E.
Cleri, Nikko J.
Dickinson, Mark
Dunlop, James S.
Finkelstein, Steven L.
Giavalisco, Mauro
Koekemoer, Anton M.
Kokorev, Vasily
Mascia, Sara
Napolitano, Lorenzo
Pentericci, Laura
Smith, Aaron
Taylor, Anthony J.
Wang, Xin
Yung, L. Y. Aaron
contents We present a study of intergalactic medium (IGM) transmission at $4.5 < z < 6.5$ using high-signal-to-noise JWST/NIRSpec prism spectroscopy of 143 galaxies at $5<z<7$ from the CAPERS and JADES surveys. By comparing the observed flux blueward of Ly$α$ emission line to the prediction of spectral energy distribution modeling, we directly measure the IGM transmission along the individual galaxy sightlines. The average transmission measured from these galaxy sightlines is consistent with previous measurements based on luminous quasars. Current NIRSpec spectroscopy is sufficiently deep to probe IGM transmission on single sightlines. We find evidence for a highly ionized structure, \bubble, at $z\sim 5.75-6$ in the GOODS-S field based on the analysis of a high-S/N spectrum of one galaxy, GS-18846, at $z=6.335$. The IGM transmission of GS-z6IS is $0.17\pm0.02$, an order of magnitude higher than the average of previous measurements at this redshift. This structure has a line-of-sight scale of $\sim110$ cMpc and spatially extends over at least $21\times17$ cMpc$^2$. GS-z6IS is associated with a known large-scale galaxy overdensity at the same redshift, whose member galaxies show enhanced Ly$α$ visibility and a broader Ly$α$ equivalent width distribution compared to field galaxies at similar redshift. This result supports the interpretation that Ly$α$ overdensity can trace bubbles of increased IGM transmission, although environmental effects on galaxy properties may also contribute. Our study demonstrates that high-S/N galaxy spectra offer a powerful new approach to tracing ionized structures during the epoch of reionization.
format Preprint
id arxiv_https___arxiv_org_abs_2605_02539
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Using Ly$α$ Transmitted Spectrum to Probe IGM Transmission and Identify Ionized Structures in Cosmic Reionization
Hu, Weida
Papovich, Casey
Shen, Lu
Haro, Pablo Arrabal
Backhaus, Bren E.
Cleri, Nikko J.
Dickinson, Mark
Dunlop, James S.
Finkelstein, Steven L.
Giavalisco, Mauro
Koekemoer, Anton M.
Kokorev, Vasily
Mascia, Sara
Napolitano, Lorenzo
Pentericci, Laura
Smith, Aaron
Taylor, Anthony J.
Wang, Xin
Yung, L. Y. Aaron
Astrophysics of Galaxies
We present a study of intergalactic medium (IGM) transmission at $4.5 < z < 6.5$ using high-signal-to-noise JWST/NIRSpec prism spectroscopy of 143 galaxies at $5<z<7$ from the CAPERS and JADES surveys. By comparing the observed flux blueward of Ly$α$ emission line to the prediction of spectral energy distribution modeling, we directly measure the IGM transmission along the individual galaxy sightlines. The average transmission measured from these galaxy sightlines is consistent with previous measurements based on luminous quasars. Current NIRSpec spectroscopy is sufficiently deep to probe IGM transmission on single sightlines. We find evidence for a highly ionized structure, \bubble, at $z\sim 5.75-6$ in the GOODS-S field based on the analysis of a high-S/N spectrum of one galaxy, GS-18846, at $z=6.335$. The IGM transmission of GS-z6IS is $0.17\pm0.02$, an order of magnitude higher than the average of previous measurements at this redshift. This structure has a line-of-sight scale of $\sim110$ cMpc and spatially extends over at least $21\times17$ cMpc$^2$. GS-z6IS is associated with a known large-scale galaxy overdensity at the same redshift, whose member galaxies show enhanced Ly$α$ visibility and a broader Ly$α$ equivalent width distribution compared to field galaxies at similar redshift. This result supports the interpretation that Ly$α$ overdensity can trace bubbles of increased IGM transmission, although environmental effects on galaxy properties may also contribute. Our study demonstrates that high-S/N galaxy spectra offer a powerful new approach to tracing ionized structures during the epoch of reionization.
title Using Ly$α$ Transmitted Spectrum to Probe IGM Transmission and Identify Ionized Structures in Cosmic Reionization
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2605.02539