MIDIS

Author(s): P. Rinaldi, K. I. Caputi, L. Costantin, S. Gillman, E. Iani, P. G. Pérez-González, G. Östlin, L. Colina, T. R. Greve, H. U. Noorgard-Nielsen, G. S. Wright, A. Alonso-Herrero, J. Álvarez-Márquez, A. Eckart, M. García-Marín, J. Hjorth, O. Ilbert, S. Kendrew, A. Labiano, O. Le Fèvre, J. Pye, T. Tikkanen, F. Walter, P. van der Werf, M. Ward, M. Annunziatella, R. Azzollini, A. Bik, L. Boogaard, S. E.I. Bosman, A. Crespo Gómez, I. Jermann, D. Langeroodi, J. Melinder, R. A. Meyer, T. Moutard, F. Peissker, M. Topinka, E. van Dishoeck, M. Güdel, Th Henning, P. O. Lagage, T. Ray, B. Vandenbussche, C. Waelkens, R. Navarro-Carrera, V. Kokorev
Abstract: We make use of JWST medium-band and broadband NIRCam imaging, along with ultradeep MIRI 5.6 μm imaging, in the Hubble eXtreme Deep Field to identify prominent line emitters at z ≃ 7-8. Out of a total of 58 galaxies at z ≃ 7-8, we find 18 robust candidates (≃31%) for (Hβ + [O iii]) emitters, based on their enhanced fluxes in the F430M and F444W filters, with EW₀(Hβ +[O iii]) ≃87-2100 Å. Among these emitters, 16 lie in the MIRI coverage area and 12 exhibit a clear flux excess at 5.6 μm, indicating the simultaneous presence of a prominent Hα emission line with EW₀(Hα) ≃200-3000 Å. This is the first time that Hα emission can be detected in individual galaxies at z > 7. The Hα line, when present, allows us to separate the contributions of Hβ and [O iii] to the (Hβ +[O iii]) complex and derive Hα-based star formation rates (SFRs). We find that in most cases [O iii]/Hβ > 1. Instead, two galaxies have [O iii]/Hβ < 1, indicating that the NIRCam flux excess is mainly driven by Hβ. Most prominent line emitters are very young starbursts or galaxies on their way to/from the starburst cloud. They make for a cosmic SFR density log 10 ( ρ SFR H α / ( M ⊙ yr − 1 Mpc − 3 ) ) ≃ − 2.35 , which is about a quarter of the total value ( log 10 ( ρ SFR tot / ( M ⊙ yr − 1 Mpc − 3 ) ) ≃ − 1.76 ) at z ≃ 7-8. Therefore, the strong Hα emitters likely had a significant role in reionization.
Organisation(s): Department of Astrophysics
External organisation(s): University of Groningen, University of Copenhagen, Centro de Astrobiología (CSIC-INTA), Technical University of Denmark (DTU), Stockholm University, The Royal Observatory, Edinburgh, Universität zu Köln, European Space Agency (ESA), Baltimore, Aix-Marseille Université, European Space Astronomy Centre (ESA), University of Leicester, Max-Planck-Institut für Astronomie, Leiden University, Durham University, INAF Astronomical Observatory of Capodimonte , Dublin Institute for Advanced Studies, Eidgenössische Technische Hochschule Zürich, Université Paris Saclay, Katholieke Universiteit Leuven
Journal: Astrophysical Journal
Volume: 952
No. of pages: 14
ISSN: 0004-637X
DOI: https://doi.org/10.3847/1538-4357/acdc27
Publication date: 08-2023
Peer reviewed: Yes
Austrian Fields of Science 2012: 103003 Astronomy, 103004 Astrophysics
ASJC Scopus subject areas: Astronomy and Astrophysics, Space and Planetary Science
Portal url: https://ucrisportal.univie.ac.at/en/publications/65562148-1e06-428c-b6cb-f97ef6e6b86c

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