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

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 oth...

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Bibliographic Details
Published in:The Astrophysical journal 2023-08, Vol.953 (1), p.53
Main Authors: Sun, Fengwu, Egami, Eiichi, Pirzkal, Nor, Rieke, Marcia, Baum, Stefi, Boyer, Martha, Boyett, Kristan, Bunker, Andrew J., Cameron, Alex J., Curti, Mirko, Eisenstein, Daniel J., Gennaro, Mario, Greene, Thomas P., Jaffe, Daniel, Kelly, Doug, Koekemoer, Anton M., Kumari, Nimisha, Maiolino, Roberto, Maseda, Michael, Perna, Michele, Rest, Armin, Robertson, Brant E., Schlawin, Everett, Smit, Renske, Stansberry, John, Sunnquist, Ben, Tacchella, Sandro, Williams, Christina C., Willmer, Christopher N. A.
Format: Article
Language:English
Subjects:
Astrophysics
Brightening
Density
Emission line galaxies
Emitters
Galaxies
Galaxy spectroscopy
H alpha line
High-redshift galaxies
Ionization
James Webb Space Telescope
Luminosity
Photons
Physical properties
Red shift
Space telescopes
Spectroscopy
Spectrum analysis
Star & galaxy formation
Star formation
Star formation rate
Starburst galaxies
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Summary: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 ] λ 5007 and H α lines with other fainter lines, which were tentatively detected in some cases (e.g., [O ii ] λ 3727, [O iii ] λ 4959). In the [O iii ]/H β –[N ii ]/H α 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 H α lines suggests a higher ionizing photon production efficiency within galaxies in the early universe. We find brightening of the [O iii ] λ 5007 line-luminosity function (LF) from z = 3 to 6, and weak or no redshift evolution of the H α 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 Ly α 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 Ly α luminosity density. Our sample recovers 66 − 44 + 128 % of z = 6.0–6.6 galaxies in the survey volume with stellar masses greater than 5 × 10 8 M ⊙ , suggesting the ubiquity of strong H α and [O iii ] line emitters in the Epoch of Reionization, which will be further uncovered in the era of JWST.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/acd53c