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Published December 2021 | Accepted Version + Published
Journal Article Open

Revealing the formation histories of the first stars with the cosmic near-infrared background

Abstract

The cosmic near-infrared background (NIRB) offers a powerful integral probe of radiative processes at different cosmic epochs, including the pre-reionization era when metal-free, Population III (Pop III) stars first formed. While the radiation from metal-enriched, Population II (Pop II) stars likely dominates the contribution to the observed NIRB from the reionization era, Pop III stars – if formed efficiently – might leave characteristic imprints on the NIRB, thanks to their strong Lyα emission. Using a physically motivated model of first star formation, we provide an analysis of the NIRB mean spectrum and anisotropy contributed by stellar populations at z > 5. We find that in circumstances where massive Pop III stars persistently form in molecular cooling haloes at a rate of a few times 10⁻³ M_⊙ yr⁻¹, before being suppressed towards the epoch of reionization (EoR) by the accumulated Lyman–Werner background, a unique spectral signature shows up redward of 1 µm in the observed NIRB spectrum sourced by galaxies at z > 5. While the detailed shape and amplitude of the spectral signature depend on various factors including the star formation histories, initial mass function, LyC escape fraction and so forth, the most interesting scenarios with efficient Pop III star formation are within the reach of forthcoming facilities, such as the Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer. As a result, new constraints on the abundance and formation history of Pop III stars at high redshifts will be available through precise measurements of the NIRB in the next few years.

Additional Information

© 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model) Accepted 2021 September 15. Received 2021 September 5; in original form 2021 July 19. The authors would like to thank Lluis Mas-Ribas for providing updated models of extended Lyα emission and comments on the early draft, as well as Jamie Bock, Tzu-Ching Chang, Asantha Cooray, Olivier Doré, Chang Feng, Caroline Heneka, and Adam Lidz for helpful discussion about SPHEREx and CDIM instruments and scientific implications. GS is indebted to David and Barbara Groce for the provision of travel funds. JM acknowledges support from a CITA National fellowship. SRF was supported by the National Science Foundation through award AST-1812458. In addition, SRF was directly supported by the NASA Solar System Exploration Research Virtual Institute cooperative agreement number 80ARC017M0006. SRF also acknowledges a NASA contract supporting the 'WFIRST Extragalactic Potential Observations (EXPO) Science Investigation Team' (15-WFIRST15-0004), administered by GSFC. DATA AVAILABILITY. No new data were generated or analysed in support of this research.

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Accepted Version - 2107.09324.pdf

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Additional details

Created:
August 22, 2023
Modified:
October 23, 2023