Closing in on the sources of cosmic reionization: First results from the GLASS-JWST program
- Creators
- Mascia, S.
- Pentericci, L.
- Calabrò, A.
- Treu, T.
- Santini, P.
- Yang, L.
- Napolitano, L.
- Roberts-Borsani, G.
- Bergamini, P.
- Grillo, C.
- Rosati, P.
- Vulcani, B.
- Castellano, M.
- Boyett, K.
- Fontana, A.
- Glazebrook, K.
- Henry, A.
- Mason, C.
- Merlin, E.
- Morishita, T.
- Nanayakkara, T.
- Paris, D.
- Roy, N.
- Williams, H.
- Wang, X.
- Brammer, G.
- Bradač, M.
- Chen, W.
- Kelly, P. L.
- Koekemoer, A. M.
- Trenti, M.
- Windhorst, R. A.
Abstract
The escape fraction of Lyman-continuum (LyC) photons (f_(esc)) is a key parameter for determining the sources of cosmic reionization at z ≥ 6. At these redshifts, owing to the opacity of the intergalactic medium, the LyC emission cannot be measured directly. However, LyC leakers during the epoch of reionization could be identified using indirect indicators that have been extensively tested at low and intermediate redshifts. These include a high [O III]/[O II] flux ratio, high star-formation surface density, and compact sizes. In this work, we present observations of 29 4.5 ≤ z ≤ 8 gravitationally lensed galaxies in the Abell 2744 cluster field. From a combined analysis of JWST-NIRSpec and NIRCam data, we accurately derived their physical and spectroscopic properties: our galaxies have low masses (log(M⋆)∼8.5), blue UV spectral slopes (β ∼ −2.1), compact sizes (r_e ∼ 0.3 − 0.5 kpc), and high [O III]/[O II] flux ratios. We confirm that these properties are similar to those characterizing low-redshift LyC leakers. Indirectly inferring the fraction of escaping ionizing photons, we find that more than 80% of our galaxies have predicted f_(esc) values larger than 0.05, indicating that they would be considered leakers. The average predicted f_(esc) value of our sample is 0.12, suggesting that similar galaxies at z ≥ 6 have provided a substantial contribution to cosmic reionization.
Additional Information
© The Authors 2023. Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. This article is published in open access under the Subscribe to Open model. Subscribe to A&A to support open access publication. Support for program JWST-ERS-1324 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127. 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 NAS 5-03127 for JWST. These observations are associated with programs GLASS-JWST #1324, JWST DDT #2756 and GO UNCOVER #2561. S.M. thanks the Department of Physics and Astronomy at the University of California, Los Angeles, for a productive and satisfying visit in which the majority of the work presented in this paper was done. We acknowledge support from the INAF Large Grant 2022 "Extragalactic Surveys with JWST" (PI: Pentericci). This research is supported in part by the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project number CE170100013. L.Y. acknowledges support by JSPS KAKENHI Grant Number JP 21F21325. R.A.W. acknowledges support from NASA JWST Interdisciplinary Scientist grants NAG5-12460, NNX14AN10G and 80NSSC18K0200 from GSFC. M.B. acknowledges support from the Slovenian national research agency ARRS through grant N1-0238. C.M. acknowledges support by the VILLUM FONDEN under grant 37459. The Cosmic Dawn Center (DAWN) is funded by the Danish National Research Foundation under grant DNRF140. K.G. and T.N. acknowledge support from Australian Research Council Laureate Fellowship FL180100060.Attached Files
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Additional details
- Eprint ID
- 121625
- Resolver ID
- CaltechAUTHORS:20230530-441768000.59
- NAS 5-03127
- NASA
- Istituto Nazionale di Astrofisica (INAF)
- CE170100013
- Australian Research Council
- JP 21F21325
- Japan Society for the Promotion of Science (JSPS)
- NAG5-12460
- NASA
- NNX14AN10G
- NASA
- 80NSSC18K0200
- NASA
- N1-0238
- Slovenian Research Agency
- 37459
- Villum Foundation
- DNRF140
- Danish National Research Foundation
- FL180100060
- Australian Research Council
- Created
-
2023-07-06Created from EPrint's datestamp field
- Updated
-
2023-07-06Created from EPrint's last_modified field
- Caltech groups
- Infrared Processing and Analysis Center (IPAC)