Deciphering Lyman-α emission deep into the epoch of reionization
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jats:titleAbstract</jats:title>jats:pDuring the epoch of reionization, the first galaxies were enshrouded in pristine neutral gas, with one of the brightest emission lines in star-forming galaxies, Lyman α (Lyα), expected to remain undetected until the Universe became ionized. Providing an explanation for the surprising detection of Lyα in these early galaxies is a major challenge for extragalactic studies. Recent James Webb Space Telescope observations have reignited the debate about whether residence in an overdensity of galaxies is a sufficient and necessary condition for Lyα to escape. Here, we take unique advantage of both high-resolution and high-sensitivity images from the James Webb Space Telescope Near Infrared Camera to show that all galaxies in a sample of Lyα emitters with redshift >7 have close companions. We exploit on-the-fly radiative-transfer magnetohydrodynamical simulations with cosmic ray feedback to show that galaxies with frequent mergers have very bursty star formation histories that drives episodes of high intrinsic Lyα emission and facilitates the escape of Lyα photons along channels cleared of neutral gas. We conclude that the rapid buildup of stellar mass through mergers presents a compelling solution to the long-standing puzzle of the detection of Lyα emission deep in the epoch of reionization.</jats:p>
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Acknowledgements: We acknowledge the work of the PRIMER core team in obtaining and reducing the NIRCam data for the COSMOS field used in this work (PI Dunlop, ID 1837). We also acknowledge the work of the CEERS team in obtaining and reducing the NIRCam data of the EGS field used in this work (PI Finkelstein, ID 1345). We acknowledge the FRESCO team’s work in obtaining observations of the GOODS-S and GOODS-N fields (PI Oesch, ID 1895). We also thank J. Rosdahl for support with the generation of radiative transfer RAMSES simulations and T. Garel for support with the use of RASCAS. We thank M. Tang, D. Stark and H. Übler for providing further information on the properties of some of our samples. Support for this work was provided by NASA through grant no. JWST-GO-01837 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. This research has used the Keck Observatory Archive, which is operated by the W. M. Keck Observatory and the NASA Exoplanet Science Institute under contract with the National Aeronautics and Space Administration and observations collected at the European Southern Observatory. This work used the DiRAC@Durham facility managed by the Institute for Computational Cosmology on behalf of the Science and Technology Facilities Council (STFC) DiRAC HPC Facility (www.dirac.ac.uk). The equipment was funded by BEIS capital funding by means of STFC capital grant nos. ST/P002293/1, ST/R002371/1 and ST/S002502/1, Durham University, and STFC operations grant no. ST/R000832/1. DiRAC is part of the National e-Infrastructure. C.W. thanks the Science and Technology Facilities Council for a PhD studentship funded by UKRI grant no. 2602262. N.L. acknowledges support from the Kavli foundation. D.S., M.G.H and J.S.D. acknowledge STFC support. P.S. acknowledges INAF mini grant no. 2022, ‘The evolution of passive galaxies through cosmic time’. R.S.E. acknowledges financial support from European Research Council advanced grant no. FP7/669253. P.G.P.-G. acknowledges support from Spanish Ministerio de Ciencia e Innovación MCIN/AEI/10.13039/501100011033 through grant no. PGC2018-093499-B-I00. D.P. acknowledges support by the Huo Family Foundation through a P.C. Ho PhD studentship. R.M., W.B. and W.M. acknowledge support by the STFC and European Research Council advanced grant no. 695671, ‘QUENCH’. R.M. also acknowledges funding from a research professorship from the Royal Society. This research was supported in part by the National Science Foundation under grant no. NSF PHY-1748958.
Funder: Kavli Foundation; doi: https://doi.org/100001201
Funder: ERC Advanced Grant 695671
Funder: ERC Advanced Grant
Funder: NASA grant JWST-GO-01837
Funder: ERC Advanced Grant 695671 Royal Society
Funder: Spanish Ministerio de Ciencia e Innovación
Funder: Huo Family Foundation
Funder: INAF - Osservatorio Astrofisico di Catania (INAF - Catania Astrophysical Observatory); doi: https://doi.org/501100006486
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2397-3366
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STFC (ST/V000918/1)
European Research Council (695671)
STFC (ST/W000997/1)