Central Concentration and Escape of Ionizing Photons in Galaxies at the Epoch of Reionization

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Main Authors: Lyu, Cheqiu, Wang, Enci, Wang, Junxian, Jia, Cheng, Song, Jie, Chen, Yangyao, Chen, Zeyu, Yu, Haoran, Ma, Chengyu, Wang, Jinyang, Wang, Yifan, Kong, Xu
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Published: 2025
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author Lyu, Cheqiu
Wang, Enci
Wang, Junxian
Jia, Cheng
Song, Jie
Chen, Yangyao
Chen, Zeyu
Yu, Haoran
Ma, Chengyu
Wang, Jinyang
Wang, Yifan
Kong, Xu
author_facet Lyu, Cheqiu
Wang, Enci
Wang, Junxian
Jia, Cheng
Song, Jie
Chen, Yangyao
Chen, Zeyu
Yu, Haoran
Ma, Chengyu
Wang, Jinyang
Wang, Yifan
Kong, Xu
contents Compact, low-mass galaxies with strong nebular emission are considered promising candidates for efficient ionizing photon production and escape. We present a spatially resolved analysis of 189 galaxies at redshifts $z \sim 6.7-7.6$ in JADES GOODS-N and GOODS-S fields and selected via JWST/NIRCam F410M filter. By employing annular photometry and spectral energy distribution fitting across rest-frame UV to optical wavelengths, we investigate the internal structure of star formation, ionizing photon production and escape, as well as the resolved star formation histories within these galaxies. We find that these galaxies exhibit compact, centrally concentrated, and bursty star formation, especially in lower-mass systems ($\log(M_*/{\rm M_{\odot}}) <9.0$). The central regions of them display extreme [OIII]+H$β$ equivalent widths ($>$1000 Å), high ionizing photon production efficiencies ($ξ_{\text{ion}} \sim 10^{25.6}$ Hz erg$^{-1}$), steep UV slopes ($\sim -2.3$), and elevated escape fractions ($f_{\text{esc}} > 0.08$), with all these properties peaking in the inner regions. These findings reveal outside-in growth and rising star formation histories at $z\sim 7$, with the central regions of them playing a pivotal role in driving cosmic reionization.
format Preprint
id arxiv_https___arxiv_org_abs_2507_16131
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Central Concentration and Escape of Ionizing Photons in Galaxies at the Epoch of Reionization
Lyu, Cheqiu
Wang, Enci
Wang, Junxian
Jia, Cheng
Song, Jie
Chen, Yangyao
Chen, Zeyu
Yu, Haoran
Ma, Chengyu
Wang, Jinyang
Wang, Yifan
Kong, Xu
Astrophysics of Galaxies
Compact, low-mass galaxies with strong nebular emission are considered promising candidates for efficient ionizing photon production and escape. We present a spatially resolved analysis of 189 galaxies at redshifts $z \sim 6.7-7.6$ in JADES GOODS-N and GOODS-S fields and selected via JWST/NIRCam F410M filter. By employing annular photometry and spectral energy distribution fitting across rest-frame UV to optical wavelengths, we investigate the internal structure of star formation, ionizing photon production and escape, as well as the resolved star formation histories within these galaxies. We find that these galaxies exhibit compact, centrally concentrated, and bursty star formation, especially in lower-mass systems ($\log(M_*/{\rm M_{\odot}}) <9.0$). The central regions of them display extreme [OIII]+H$β$ equivalent widths ($>$1000 Å), high ionizing photon production efficiencies ($ξ_{\text{ion}} \sim 10^{25.6}$ Hz erg$^{-1}$), steep UV slopes ($\sim -2.3$), and elevated escape fractions ($f_{\text{esc}} > 0.08$), with all these properties peaking in the inner regions. These findings reveal outside-in growth and rising star formation histories at $z\sim 7$, with the central regions of them playing a pivotal role in driving cosmic reionization.
title Central Concentration and Escape of Ionizing Photons in Galaxies at the Epoch of Reionization
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2507.16131