First Sample of Hα+[O iii]λ5007 Line Emitters at z > 6 Through JWST/NIRCam Slitless Spectroscopy: Physical Properties and Line-luminosity Functions

Sun, F ORCID: 0000-0002-4622-6617, Egami, E ORCID: 0000-0003-1344-9475, Pirzkal, N ORCID: 0000-0003-3382-5941, Rieke, M ORCID: 0000-0002-7893-6170, Baum, S ORCID: 0000-0002-4735-8224, Boyer, M ORCID: 0000-0003-4850-9589, Boyett, K ORCID: 0000-0003-4109-304X, Bunker, AJ ORCID: 0000-0002-8651-9879, Cameron, AJ ORCID: 0000-0002-0450-7306, Curti, M ORCID: 0000-0002-2678-2560, Eisenstein, DJ ORCID: 0000-0002-2929-3121, Gennaro, M ORCID: 0000-0002-5581-2896, Greene, TP ORCID: 0000-0002-8963-8056, Jaffe, D ORCID: 0000-0003-3577-3540, Kelly, D, Koekemoer, AM ORCID: 0000-0002-6610-2048, Kumari, N ORCID: 0000-0002-5320-2568, Maiolino, R ORCID: 0000-0002-4985-3819, Maseda, M ORCID: 0000-0003-0695-4414, Perna, M ORCID: 0000-0002-0362-5941 et al (2023) First Sample of Hα+[O iii]λ5007 Line Emitters at z > 6 Through JWST/NIRCam Slitless Spectroscopy: Physical Properties and Line-luminosity Functions. Astrophysical Journal, 953 (1). ISSN 0004-637X

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Abstract

We present a sample of four emission-line galaxies at z = 6.11–6.35 that were serendipitously discovered using the commissioning data for the James Webb Space Telescope (JWST)/NIRCam wide-field slitless spectroscopy mode. One of them (at z = 6.11) has been reported previously, while the others are new discoveries. These sources are selected by the secure detections of both [O iii] λ5007 and Hα lines with other fainter lines, which were tentatively detected in some cases (e.g., [O ii] λ3727, [O iii] λ4959). In the [O iii]/Hβ–[N ii]/Hα Baldwin–Phillips–Terlevich diagram, these galaxies occupy the same parameter space as that of z ∼ 2 star-forming galaxies, indicating that they have been enriched rapidly to subsolar metallicities (∼0.4 Z⊙), similar to galaxies with comparable stellar masses at much lower redshifts. The detection of strong Hα lines suggests a higher ionizing photon production efficiency within galaxies in the early universe. We find brightening of the [O iii] λ5007 line-luminosity function (LF) from z = 3 to 6, and weak or no redshift evolution of the Hα line LF from z = 2 to 6. Both LFs are underpredicted at z ∼ 6 by a factor of ∼10 in certain cosmological simulations. This further indicates a global Lyα photon escape fraction of 7%–10% at z ∼ 6, which is slightly lower than previous estimates through the comparison of the UV-derived star formation rate density and Lyα luminosity density. Our sample recovers
66 +28 -44 % of z = 6.0–6.6 galaxies in the survey volume with stellar masses greater than 5 × 108M⊙, suggesting the ubiquity of strong Hα and [O iii] line emitters in the Epoch of Reionization, which will be further uncovered in the era of JWST.

Item Type:	Article
Uncontrolled Keywords:	0201 Astronomical and Space Sciences; 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics; 0306 Physical Chemistry (incl. Structural); Astronomy & Astrophysics
Subjects:	Q Science > QB Astronomy
Divisions:	Astrophysics Research Institute
Publisher:	American Astronomical Society
Date of acceptance:	11 May 2023
Date of first compliant Open Access:	12 December 2023
Date Deposited:	12 Dec 2023 15:13
Last Modified:	03 Jul 2025 12:36
DOI or ID number:	10.3847/1538-4357/acd53c
URI:	https://researchonline.ljmu.ac.uk/id/eprint/22086

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