SMILES: Potentially Higher Ionizing Photon Production Efficiency in Overdense Regions

The topology of reionization and the environments where galaxies efficiently produce ionizing photons are key open questions. For the first time, we investigate the trend between ionizing photon production efficiency, ξ _ion , and galaxy overdensity, $\mathrm{log}(1+\delta )$ . We analyze the ionizi...

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Main Authors: Yongda Zhu, Stacey Alberts, Jianwei Lyu, Jane Morrison, George H. Rieke, Yang Sun, Jakob M. Helton, Zhiyuan Ji, Rachana Bhatawdekar, Nina Bonaventura, Andrew J. Bunker, Xiaojing Lin, Marcia J. Rieke, Pierluigi Rinaldi, Irene Shivaei, Christopher N. A. Willmer, Junyu Zhang
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
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Online Access:https://doi.org/10.3847/1538-4357/add263
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author Yongda Zhu
Stacey Alberts
Jianwei Lyu
Jane Morrison
George H. Rieke
Yang Sun
Jakob M. Helton
Zhiyuan Ji
Rachana Bhatawdekar
Nina Bonaventura
Andrew J. Bunker
Xiaojing Lin
Marcia J. Rieke
Pierluigi Rinaldi
Irene Shivaei
Christopher N. A. Willmer
Junyu Zhang
author_facet Yongda Zhu
Stacey Alberts
Jianwei Lyu
Jane Morrison
George H. Rieke
Yang Sun
Jakob M. Helton
Zhiyuan Ji
Rachana Bhatawdekar
Nina Bonaventura
Andrew J. Bunker
Xiaojing Lin
Marcia J. Rieke
Pierluigi Rinaldi
Irene Shivaei
Christopher N. A. Willmer
Junyu Zhang
author_sort Yongda Zhu
collection DOAJ
description The topology of reionization and the environments where galaxies efficiently produce ionizing photons are key open questions. For the first time, we investigate the trend between ionizing photon production efficiency, ξ _ion , and galaxy overdensity, $\mathrm{log}(1+\delta )$ . We analyze the ionizing properties of 79 galaxies between 1.0 <  z  < 5.2 using JWST NIRSpec medium-resolution spectra from the Systematic Mid-infrared Instrument Legacy Extragalactic Survey (SMILES) program. Among these, 67 galaxies have H α coverage, spanning 1.0 <  z  < 3.1. The galaxy overdensity, $\mathrm{log}(1+\delta )$ , is measured using the JADES photometric catalog, which covers the SMILES footprint. For the subset with H α coverage, we find that $\mathrm{log}{\xi }_{{\rm{ion}}}$ is positively correlated with $\mathrm{log}(1+\delta )$ , with a slope of $0.9{4}_{-0.46}^{+0.46}$ . Additionally, the mean ξ _ion for galaxies in overdense regions ( $\mathrm{log}(1+\delta )\gt 0.1$ ) is 2.43 times that of galaxies in lower density regions ( $\mathrm{log}(1+\delta )\lt 0.1$ ). This strong trend is found to be independent of redshift evolution. Furthermore, our results confirm the robust correlations between ξ _ion and the rest-frame equivalent widths of the [O iii ] or H α emission lines. Our results suggest that galaxies in high-density regions are efficient producers of ionizing photons.
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spelling doaj-art-af3571e433f34376977e802f672696e82025-08-20T03:07:28ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0198611810.3847/1538-4357/add263SMILES: Potentially Higher Ionizing Photon Production Efficiency in Overdense RegionsYongda Zhu0https://orcid.org/0000-0003-3307-7525Stacey Alberts1https://orcid.org/0000-0002-8909-8782Jianwei Lyu2https://orcid.org/0000-0002-6221-1829Jane Morrison3https://orcid.org/0000-0002-9288-9235George H. Rieke4https://orcid.org/0000-0003-2303-6519Yang Sun5https://orcid.org/0000-0001-6561-9443Jakob M. Helton6https://orcid.org/0000-0003-4337-6211Zhiyuan Ji7https://orcid.org/0000-0001-7673-2257Rachana Bhatawdekar8https://orcid.org/0000-0003-0883-2226Nina Bonaventura9https://orcid.org/0000-0001-8470-7094Andrew J. Bunker10https://orcid.org/0000-0002-8651-9879Xiaojing Lin11https://orcid.org/0000-0001-6052-4234Marcia J. Rieke12https://orcid.org/0000-0002-7893-6170Pierluigi Rinaldi13https://orcid.org/0000-0002-5104-8245Irene Shivaei14https://orcid.org/0000-0003-4702-7561Christopher N. A. Willmer15https://orcid.org/0000-0001-9262-9997Junyu Zhang16https://orcid.org/0000-0002-1574-2045Steward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ 85721, USA ; yongdaz@arizona.eduSteward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ 85721, USA ; yongdaz@arizona.eduSteward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ 85721, USA ; yongdaz@arizona.eduSteward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ 85721, USA ; yongdaz@arizona.eduSteward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ 85721, USA ; yongdaz@arizona.eduSteward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ 85721, USA ; yongdaz@arizona.eduSteward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ 85721, USA ; yongdaz@arizona.eduSteward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ 85721, USA ; yongdaz@arizona.eduEuropean Space Agency (ESA) , European Space Astronomy Centre (ESAC), Camino Bajo del Castillo s/n, 28692 Villanueva de la Cañada, Madrid, SpainSteward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ 85721, USA ; yongdaz@arizona.eduDepartment of Physics, University of Oxford , Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UKSteward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ 85721, USA ; yongdaz@arizona.edu; Department of Astronomy, Tsinghua University , Beijing 100084, People’s Republic of ChinaSteward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ 85721, USA ; yongdaz@arizona.eduSteward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ 85721, USA ; yongdaz@arizona.eduCentro de Astrobiología (CAB) , CSIC-INTA, Ctra. de Ajalvir km 4, Torrejón de Ardoz, E-28850, Madrid, SpainSteward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ 85721, USA ; yongdaz@arizona.eduSteward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ 85721, USA ; yongdaz@arizona.eduThe topology of reionization and the environments where galaxies efficiently produce ionizing photons are key open questions. For the first time, we investigate the trend between ionizing photon production efficiency, ξ _ion , and galaxy overdensity, $\mathrm{log}(1+\delta )$ . We analyze the ionizing properties of 79 galaxies between 1.0 <  z  < 5.2 using JWST NIRSpec medium-resolution spectra from the Systematic Mid-infrared Instrument Legacy Extragalactic Survey (SMILES) program. Among these, 67 galaxies have H α coverage, spanning 1.0 <  z  < 3.1. The galaxy overdensity, $\mathrm{log}(1+\delta )$ , is measured using the JADES photometric catalog, which covers the SMILES footprint. For the subset with H α coverage, we find that $\mathrm{log}{\xi }_{{\rm{ion}}}$ is positively correlated with $\mathrm{log}(1+\delta )$ , with a slope of $0.9{4}_{-0.46}^{+0.46}$ . Additionally, the mean ξ _ion for galaxies in overdense regions ( $\mathrm{log}(1+\delta )\gt 0.1$ ) is 2.43 times that of galaxies in lower density regions ( $\mathrm{log}(1+\delta )\lt 0.1$ ). This strong trend is found to be independent of redshift evolution. Furthermore, our results confirm the robust correlations between ξ _ion and the rest-frame equivalent widths of the [O iii ] or H α emission lines. Our results suggest that galaxies in high-density regions are efficient producers of ionizing photons.https://doi.org/10.3847/1538-4357/add263High-redshift galaxiesReionization
spellingShingle Yongda Zhu
Stacey Alberts
Jianwei Lyu
Jane Morrison
George H. Rieke
Yang Sun
Jakob M. Helton
Zhiyuan Ji
Rachana Bhatawdekar
Nina Bonaventura
Andrew J. Bunker
Xiaojing Lin
Marcia J. Rieke
Pierluigi Rinaldi
Irene Shivaei
Christopher N. A. Willmer
Junyu Zhang
SMILES: Potentially Higher Ionizing Photon Production Efficiency in Overdense Regions
The Astrophysical Journal
High-redshift galaxies
Reionization
title SMILES: Potentially Higher Ionizing Photon Production Efficiency in Overdense Regions
title_full SMILES: Potentially Higher Ionizing Photon Production Efficiency in Overdense Regions
title_fullStr SMILES: Potentially Higher Ionizing Photon Production Efficiency in Overdense Regions
title_full_unstemmed SMILES: Potentially Higher Ionizing Photon Production Efficiency in Overdense Regions
title_short SMILES: Potentially Higher Ionizing Photon Production Efficiency in Overdense Regions
title_sort smiles potentially higher ionizing photon production efficiency in overdense regions
topic High-redshift galaxies
Reionization
url https://doi.org/10.3847/1538-4357/add263
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