Inside the bubble: exploring the environments of reionisation-era Lyman-α emitting galaxies with JADES and FRESCO
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Published:2024-01-31
Issue:
Volume:682
Page:A40
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ISSN:0004-6361
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Container-title:Astronomy & Astrophysics
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language:
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Short-container-title:A&A
Author:
Witstok JorisORCID, Smit RenskeORCID, Saxena AayushORCID, Jones Gareth C.ORCID, Helton Jakob M.ORCID, Sun FengwuORCID, Maiolino RobertoORCID, Kumari NimishaORCID, Stark Daniel P.ORCID, Bunker Andrew J.ORCID, Arribas SantiagoORCID, Baker William M.ORCID, Bhatawdekar RachanaORCID, Boyett KristanORCID, Cameron Alex J.ORCID, Carniani StefanoORCID, Charlot StephaneORCID, Chevallard JacopoORCID, Curti MirkoORCID, Curtis-Lake EmmaORCID, Eisenstein Daniel J.ORCID, Endsley RyanORCID, Hainline KevinORCID, Ji ZhiyuanORCID, Johnson Benjamin D.ORCID, Looser Tobias J.ORCID, Nelson EricaORCID, Perna MicheleORCID, Rix Hans-WalterORCID, Robertson Brant E.ORCID, Sandles LesterORCID, Scholtz Jan, Simmonds CharlotteORCID, Tacchella SandroORCID, Übler HannahORCID, Williams Christina C.ORCID, Willmer Christopher N. A.ORCID, Willott ChrisORCID
Abstract
We present a study of the environments of 17 Lyman-α emitting galaxies (LAEs) in the reionisation-era (5.8 < z < 8) identified by JWST/NIRSpec as part of the JWST Advanced Deep Extragalactic Survey (JADES). Unless situated in sufficiently (re)ionised regions, Lyman-α emission from these galaxies would be strongly absorbed by neutral gas in the intergalactic medium (IGM). We conservatively estimate sizes of the ionised regions required to reconcile the relatively low Lyman-α velocity offsets (ΔvLyα < 300 km s−1) with moderately high Lyman-α escape fractions (fesc, Lyα > 5%) observed in our sample of LAEs, suggesting the presence of ionised hydrogen along the line of sight towards at least eight out of 17 LAEs. We find minimum physical ‘bubble’ sizes of the order of Rion ∼ 0.1–1 pMpc are required in a patchy reionisation scenario where ionised bubbles containing the LAEs are embedded in a fully neutral IGM. Around half of the LAEs in our sample are found to coincide with large-scale galaxy overdensities seen in FRESCO at z ∼ 5.8–5.9 and z ∼ 7.3, suggesting Lyman-α transmission is strongly enhanced in such overdense regions, and underlining the importance of LAEs as tracers of the first large-scale ionised bubbles. Considering only spectroscopically confirmed galaxies, we find our sample of UV-faint LAEs (MUV ≳ −20 mag) and their direct neighbours are generally not able to produce the required ionised regions based on the Lyman-α transmission properties, suggesting lower-luminosity sources likely play an important role in carving out these bubbles. These observations demonstrate the combined power of JWST multi-object and slitless spectroscopy in acquiring a unique view of the early Universe during cosmic reionisation via the most distant LAEs.
Funder
Science and Technology Facilities Council European Research Council UK Research and Innovation Fondation Merac Royal Society Ministerio de Ciencia e Innovación ASTRO3D Programa Atracción de Talento de la Comunidad de Madrid Isaac Newton Trust Kavli Foundation NOIRLab
Subject
Space and Planetary Science,Astronomy and Astrophysics
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