A Spectroscopic Analysis of the Ionizing Photon Production Efficiency in JADES and CEERS: Implications for the Ionizing Photon Budget

Anthony Pahl; Michael W. Topping; Alice Shapley; Ryan Sanders; Naveen A. Reddy; Leonardo Clarke; Emily Kehoe; Trinity Bento; Gabe Brammer

doi:10.3847/1538-4357/adb1ab

A Spectroscopic Analysis of the Ionizing Photon Production Efficiency in JADES and CEERS: Implications for the Ionizing Photon Budget

Anthony Pahl
, Michael W. Topping
, Alice Shapley
, Ryan Sanders
, Naveen A. Reddy
, Leonardo Clarke
, Emily Kehoe
, Trinity Bento
, Gabe Brammer

Physics And Astronomy

Research output: Contribution to journal › Article › peer-review

31 Scopus citations

Abstract

We have used a combined sample of JADES and CEERS objects in order to constrain ionizing photon production efficiency (ξ_ion) from JWST/NIRSpec and JWST/NIRCam data. We examine 163 objects at 1.06 < z < 6.71 with significant (3σ) spectroscopic detections of Hα and Hβ in order to constrain intrinsic Hα luminosities corrected from nebular dust attenuation via Balmer decrements. We constrain dust-corrected UV luminosities from best-fit spectral energy distribution modeling. We find a sample median log 10 ( ξ ion,0 / erg Hz − 1 ) = 25.2 9 − 0.37 + 0.29 , assuming f_esc= 0 for the escape fraction of Lyman continuum (LyC) emission. We find significant (Spearman r_s = 0.19, p = 0.01) correlation between ξ_ion,0 and z, with objects at z > 4.64 having median log 10 ( ξ ion,0 / erg Hz − 1 ) = 25.3 8 − 0.38 + 0.38 , with those below having log 10 ( ξ ion,0 / erg Hz − 1 ) = 25.2 4 − 0.33 + 0.30 . We also find significant, positive correlations between ξ_ion,0 and L_UV; W_λ([O iii]); [O iii]λ5007/[O ii]λλ3726, 3729; and inverse correlations with metallicity. In contrast with some previous results, we find no trends between ξ_ion,0 and stellar mass, stellar dust attenuation, or UV slope. Applying a multivariate fit to ξ_ion,0, z, and M_UV to an empirically motivated model of reionization, and folding in f_esc estimates from direct observations of the LyC at z ∼ 3 from the Keck Lyman Continuum Spectroscopic Survey, we find that the number of ionizing photons entering the IGM causes reionization to end at z ∼ 5-7.

Original language	English
Article number	134
Journal	Astrophysical Journal
Volume	981
Issue number	2
DOIs	https://doi.org/10.3847/1538-4357/adb1ab
State	Published - Mar 10 2025

Bibliographical note

Publisher Copyright:
© 2025. The Author(s). Published by the American Astronomical Society.

Funding

We acknowledge the CEERS and JADES teams for their effort to design, execute, and make public their observational surveys. A.J.P. would like to give thanks for the discussions with Gwen Rudie and Julian Muñoz on science and reionization models, respectively. A.J.P. was generously supported by a Carnegie Fellowship through the Carnegie Observatories while conducting this work. This work is based on observations made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-03127 for JWST. Data were also obtained from the DAWN JWST Archive maintained by the Cosmic Dawn Center. The JWST data used in this paper can be found in MAST: doi:10.17909/z7p0-8481, doi:10.17909/8tdj-8n28.

Funders	Funder number
National Aeronautics and Space Administration
Epsilon Sigma Alpha
Colorado State Archives	NAS5-03127
Colorado State Archives

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.3847/1538-4357/adb1ab

Cite this

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title = "A Spectroscopic Analysis of the Ionizing Photon Production Efficiency in JADES and CEERS: Implications for the Ionizing Photon Budget",

abstract = "We have used a combined sample of JADES and CEERS objects in order to constrain ionizing photon production efficiency (ξion) from JWST/NIRSpec and JWST/NIRCam data. We examine 163 objects at 1.06 < z < 6.71 with significant (3σ) spectroscopic detections of Hα and Hβ in order to constrain intrinsic Hα luminosities corrected from nebular dust attenuation via Balmer decrements. We constrain dust-corrected UV luminosities from best-fit spectral energy distribution modeling. We find a sample median log 10 ( ξ ion,0 / erg Hz − 1 ) = 25.2 9 − 0.37 + 0.29 , assuming fesc = 0 for the escape fraction of Lyman continuum (LyC) emission. We find significant (Spearman rs = 0.19, p = 0.01) correlation between ξion,0 and z, with objects at z > 4.64 having median log 10 ( ξ ion,0 / erg Hz − 1 ) = 25.3 8 − 0.38 + 0.38 , with those below having log 10 ( ξ ion,0 / erg Hz − 1 ) = 25.2 4 − 0.33 + 0.30 . We also find significant, positive correlations between ξion,0 and LUV; Wλ([O iii]); [O iii]λ5007/[O ii]λλ3726, 3729; and inverse correlations with metallicity. In contrast with some previous results, we find no trends between ξion,0 and stellar mass, stellar dust attenuation, or UV slope. Applying a multivariate fit to ξion,0, z, and MUV to an empirically motivated model of reionization, and folding in fesc estimates from direct observations of the LyC at z ∼ 3 from the Keck Lyman Continuum Spectroscopic Survey, we find that the number of ionizing photons entering the IGM causes reionization to end at z ∼ 5-7.",

author = "Anthony Pahl and Topping, \{Michael W.\} and Alice Shapley and Ryan Sanders and Reddy, \{Naveen A.\} and Leonardo Clarke and Emily Kehoe and Trinity Bento and Gabe Brammer",

note = "Publisher Copyright: {\textcopyright} 2025. The Author(s). Published by the American Astronomical Society.",

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month = mar,

day = "10",

doi = "10.3847/1538-4357/adb1ab",

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T1 - A Spectroscopic Analysis of the Ionizing Photon Production Efficiency in JADES and CEERS

T2 - Implications for the Ionizing Photon Budget

AU - Pahl, Anthony

AU - Topping, Michael W.

AU - Shapley, Alice

AU - Sanders, Ryan

AU - Reddy, Naveen A.

AU - Clarke, Leonardo

AU - Kehoe, Emily

AU - Bento, Trinity

AU - Brammer, Gabe

PY - 2025/3/10

Y1 - 2025/3/10

N2 - We have used a combined sample of JADES and CEERS objects in order to constrain ionizing photon production efficiency (ξion) from JWST/NIRSpec and JWST/NIRCam data. We examine 163 objects at 1.06 < z < 6.71 with significant (3σ) spectroscopic detections of Hα and Hβ in order to constrain intrinsic Hα luminosities corrected from nebular dust attenuation via Balmer decrements. We constrain dust-corrected UV luminosities from best-fit spectral energy distribution modeling. We find a sample median log 10 ( ξ ion,0 / erg Hz − 1 ) = 25.2 9 − 0.37 + 0.29 , assuming fesc = 0 for the escape fraction of Lyman continuum (LyC) emission. We find significant (Spearman rs = 0.19, p = 0.01) correlation between ξion,0 and z, with objects at z > 4.64 having median log 10 ( ξ ion,0 / erg Hz − 1 ) = 25.3 8 − 0.38 + 0.38 , with those below having log 10 ( ξ ion,0 / erg Hz − 1 ) = 25.2 4 − 0.33 + 0.30 . We also find significant, positive correlations between ξion,0 and LUV; Wλ([O iii]); [O iii]λ5007/[O ii]λλ3726, 3729; and inverse correlations with metallicity. In contrast with some previous results, we find no trends between ξion,0 and stellar mass, stellar dust attenuation, or UV slope. Applying a multivariate fit to ξion,0, z, and MUV to an empirically motivated model of reionization, and folding in fesc estimates from direct observations of the LyC at z ∼ 3 from the Keck Lyman Continuum Spectroscopic Survey, we find that the number of ionizing photons entering the IGM causes reionization to end at z ∼ 5-7.

AB - We have used a combined sample of JADES and CEERS objects in order to constrain ionizing photon production efficiency (ξion) from JWST/NIRSpec and JWST/NIRCam data. We examine 163 objects at 1.06 < z < 6.71 with significant (3σ) spectroscopic detections of Hα and Hβ in order to constrain intrinsic Hα luminosities corrected from nebular dust attenuation via Balmer decrements. We constrain dust-corrected UV luminosities from best-fit spectral energy distribution modeling. We find a sample median log 10 ( ξ ion,0 / erg Hz − 1 ) = 25.2 9 − 0.37 + 0.29 , assuming fesc = 0 for the escape fraction of Lyman continuum (LyC) emission. We find significant (Spearman rs = 0.19, p = 0.01) correlation between ξion,0 and z, with objects at z > 4.64 having median log 10 ( ξ ion,0 / erg Hz − 1 ) = 25.3 8 − 0.38 + 0.38 , with those below having log 10 ( ξ ion,0 / erg Hz − 1 ) = 25.2 4 − 0.33 + 0.30 . We also find significant, positive correlations between ξion,0 and LUV; Wλ([O iii]); [O iii]λ5007/[O ii]λλ3726, 3729; and inverse correlations with metallicity. In contrast with some previous results, we find no trends between ξion,0 and stellar mass, stellar dust attenuation, or UV slope. Applying a multivariate fit to ξion,0, z, and MUV to an empirically motivated model of reionization, and folding in fesc estimates from direct observations of the LyC at z ∼ 3 from the Keck Lyman Continuum Spectroscopic Survey, we find that the number of ionizing photons entering the IGM causes reionization to end at z ∼ 5-7.

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UR - https://www.scopus.com/pages/publications/86000320139#tab=citedBy

U2 - 10.3847/1538-4357/adb1ab

DO - 10.3847/1538-4357/adb1ab

M3 - Article

AN - SCOPUS:86000320139

SN - 0004-637X

VL - 981

JO - Astrophysical Journal

JF - Astrophysical Journal

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M1 - 134

ER -

A Spectroscopic Analysis of the Ionizing Photon Production Efficiency in JADES and CEERS: Implications for the Ionizing Photon Budget

Abstract

Bibliographical note

Funding

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