MIDIS: Strong (Hβ+[O III]) and Hα Emitters at Redshift z ≃ 7-8 Unveiled with JWST NIRCam and MIRI Imaging in the Hubble eXtreme Deep Field
Journal
Date Issued
2023
Author(s)
Rinaldi, P.
•
Caputi, K. I.
•
COSTANTIN, LUCA
•
Gillman, S.
•
Iani, E.
•
Pérez-González, P. G.
•
Östlin, G.
•
Colina, L.
•
Greve, T. R.
•
Noorgard-Nielsen, H. U.
•
Wright, G. S.
•
Alonso-Herrero, A.
•
Álvarez-Márquez, J.
•
Eckart, A.
•
García-Marín, M.
•
Hjorth, J.
•
Ilbert, O.
•
Kendrew, S.
•
Labiano, A.
•
Le Fèvre, O.
•
Pye, J.
•
Tikkanen, T.
•
Walter, F.
•
van der Werf, P.
•
Ward, M.
•
Annunziatella, M.
•
Azzollini, R.
•
Bik, A.
•
Boogaard, L.
•
Bosman, S. E. I.
•
Crespo Gómez, A.
•
Jermann, I.
•
Langeroodi, D.
•
Melinder, J.
•
Meyer, R. A.
•
Moutard, T.
•
Peissker, F.
•
•
van Dishoeck, E.
•
Güdel, M.
•
Henning, Th.
•
Lagage, P. -O.
•
Ray, T.
•
Vandenbussche, B.
•
Waelkens, C.
•
Navarro-Carrera, R.
•
Kokorev, V.
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 ${\mathrm{log}}_{10}({\rho }_{{\mathrm{SFR}}_{{\rm{H}}\alpha }}/({M}_{\odot }\,{\mathrm{yr}}^{-1}\,{\mathrm{Mpc}}^{-3}))\simeq -2.35$ , which is about a quarter of the total value ( ${\mathrm{log}}_{10}({\rho }_{{\mathrm{SFR}}_{\mathrm{tot}}}/({M}_{\odot }\,{\mathrm{yr}}^{-1}\,{\mathrm{Mpc}}^{-3}))\simeq -1.76$ ) at z ≃ 7-8. Therefore, the strong Hα emitters likely had a significant role in reionization.
Volume
952
Issue
2
Start page
143
Issn Identifier
0004-637X
Ads BibCode
2023ApJ...952..143R
Rights
open.access
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