TY - JOUR
T1 - A Comprehensive Study of Galaxies at z ∼ 9-16 Found in the Early JWST Data
T2 - Ultraviolet Luminosity Functions and Cosmic Star Formation History at the Pre-reionization Epoch
AU - Harikane, Yuichi
AU - Ouchi, Masami
AU - Oguri, Masamune
AU - Ono, Yoshiaki
AU - Nakajima, Kimihiko
AU - Isobe, Yuki
AU - Umeda, Hiroya
AU - Mawatari, Ken
AU - Zhang, Yechi
N1 - Publisher Copyright:
© 2023. The Author(s). Published by the American Astronomical Society.
PY - 2023/3/1
Y1 - 2023/3/1
N2 - We conduct a comprehensive study on dropout galaxy candidates at z ∼ 9-16 using the first 90 arcmin2 James Webb Space Telescope (JWST) Near Infrared Camera images taken by the early release observations (ERO) and early release science programs. With the JWST simulation images, we find that a number of foreground interlopers are selected with a weak photo-z determination (Δχ 2 > 4). We thus carefully apply a secure photo-z selection criterion (Δχ 2 > 9) and conventional color criteria with confirmations of the ERO Near Infrared Spectrograph spectroscopic redshifts, and obtain a total of 23 dropout galaxies at z ∼ 9-16, including two candidates at z phot = 16.25 − 0.46 + 0.24 and 16.41 − 0.55 + 0.66 . We perform thorough comparisons of dropout galaxies found in our work with recent JWST studies, and conclude that our galaxy sample is reliable enough for statistical analyses. We derive the UV luminosity functions at z ∼ 9-16, and confirm that our UV luminosity functions at z ∼ 9 and 12 agree with those determined by other Hubble Space Telescope and JWST studies. The cosmic star formation rate (SFR) density decreases from z ∼ 9 to 12, and perhaps to 16, but the densities at z ∼ 12-16 are higher than the constant star formation efficiency model. Interestingly, there are six bright galaxy candidates at z ∼ 10-16 with M UV < −19.5 mag and M * ∼ 108−9 M ⊙. Because a majority (∼80%) of these galaxies show no signatures of active galactic nuclei in their morphologies, the high cosmic SFR densities and the existence of these UV-luminous galaxies are explained by the lack of suppression of star formation by the UV background radiation at the pre-reionization epoch and/or an efficient UV radiation production by a top-heavy initial mass function with Population III-like star formation.
AB - We conduct a comprehensive study on dropout galaxy candidates at z ∼ 9-16 using the first 90 arcmin2 James Webb Space Telescope (JWST) Near Infrared Camera images taken by the early release observations (ERO) and early release science programs. With the JWST simulation images, we find that a number of foreground interlopers are selected with a weak photo-z determination (Δχ 2 > 4). We thus carefully apply a secure photo-z selection criterion (Δχ 2 > 9) and conventional color criteria with confirmations of the ERO Near Infrared Spectrograph spectroscopic redshifts, and obtain a total of 23 dropout galaxies at z ∼ 9-16, including two candidates at z phot = 16.25 − 0.46 + 0.24 and 16.41 − 0.55 + 0.66 . We perform thorough comparisons of dropout galaxies found in our work with recent JWST studies, and conclude that our galaxy sample is reliable enough for statistical analyses. We derive the UV luminosity functions at z ∼ 9-16, and confirm that our UV luminosity functions at z ∼ 9 and 12 agree with those determined by other Hubble Space Telescope and JWST studies. The cosmic star formation rate (SFR) density decreases from z ∼ 9 to 12, and perhaps to 16, but the densities at z ∼ 12-16 are higher than the constant star formation efficiency model. Interestingly, there are six bright galaxy candidates at z ∼ 10-16 with M UV < −19.5 mag and M * ∼ 108−9 M ⊙. Because a majority (∼80%) of these galaxies show no signatures of active galactic nuclei in their morphologies, the high cosmic SFR densities and the existence of these UV-luminous galaxies are explained by the lack of suppression of star formation by the UV background radiation at the pre-reionization epoch and/or an efficient UV radiation production by a top-heavy initial mass function with Population III-like star formation.
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U2 - 10.3847/1538-4365/acaaa9
DO - 10.3847/1538-4365/acaaa9
M3 - Article
AN - SCOPUS:85148445011
SN - 0067-0049
VL - 265
JO - Astrophysical Journal, Supplement Series
JF - Astrophysical Journal, Supplement Series
IS - 1
M1 - 5
ER -