TY - JOUR
T1 - A Lower Bound of Star Formation Activity in Ultra-high-redshift Galaxies Detected with JWST
T2 - Implications for Stellar Populations and Radiation Sources
AU - Inayoshi, Kohei
AU - Harikane, Yuichi
AU - Inoue, Akio K.
AU - Li, Wenxiu
AU - Ho, Luis C.
N1 - Funding Information:
We greatly thank Hajime Fukushima, Jia Liu, Kazuyuki Omukai, Masafusa Onoue, Masami Ouchi, Shun Saito, and Kazuyuki Sugimura for constructive discussions. We acknowledge support from the National Natural Science Foundation of China (12073003, 12003003, 11721303, 11991052, and 11950410493), and the China Manned Space Project (CMS-CSST-2021-A04 and CMS-CSST-2021-A06). A.K.I. acknowledges support from NAOJ ALMA Scientific Research grant code 2020-16B. Y.H. is supported by the joint research program of the Institute for Cosmic Ray Research (ICRR), University of Tokyo, and JSPS KAKENHI grant No. 21K13953.
Publisher Copyright:
© 2022. The Author(s). Published by the American Astronomical Society.
PY - 2022/10/1
Y1 - 2022/10/1
N2 - Early results of James Webb Space Telescope observations have delivered bright z ≳ 10 galaxy candidates in greater numbers than expected, enabling construction of rest-frame UV luminosity functions (LFs). The LFs contain key information on the galaxy assembly history, star formation activity, and stellar population of the distant universe. Given an upper bound of the total baryonic mass inflow rate to galaxies from their parent halos estimated from abundance matching, we derive a lower bound on the product of the star formation and UV photon production efficiency in galaxies at each redshift. This stringent constraint requires a high efficiency (≳10%-30%) converting gas into stars, assuming a normal stellar population with a Salpeter-like mass distribution. The efficiency is substantially higher than those of typical nearby galaxies, but is consistent with those seen in starburst galaxies and super-star clusters observed in the nearby universe. Alternatively, the star formation efficiency may be as low as a few percent, which is the average value for the entire galaxy population at z ≃ 6, if the stellar population is metal-free and drawn from a top-heavy mass distribution that produces more intense UV radiation. We discuss several other possible scenarios to achieve the constraint, for instance, energetic radiation produced from compact stellar remnants and quasars, and propose ways to distinguish the scenarios by forthcoming observations.
AB - Early results of James Webb Space Telescope observations have delivered bright z ≳ 10 galaxy candidates in greater numbers than expected, enabling construction of rest-frame UV luminosity functions (LFs). The LFs contain key information on the galaxy assembly history, star formation activity, and stellar population of the distant universe. Given an upper bound of the total baryonic mass inflow rate to galaxies from their parent halos estimated from abundance matching, we derive a lower bound on the product of the star formation and UV photon production efficiency in galaxies at each redshift. This stringent constraint requires a high efficiency (≳10%-30%) converting gas into stars, assuming a normal stellar population with a Salpeter-like mass distribution. The efficiency is substantially higher than those of typical nearby galaxies, but is consistent with those seen in starburst galaxies and super-star clusters observed in the nearby universe. Alternatively, the star formation efficiency may be as low as a few percent, which is the average value for the entire galaxy population at z ≃ 6, if the stellar population is metal-free and drawn from a top-heavy mass distribution that produces more intense UV radiation. We discuss several other possible scenarios to achieve the constraint, for instance, energetic radiation produced from compact stellar remnants and quasars, and propose ways to distinguish the scenarios by forthcoming observations.
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U2 - 10.3847/2041-8213/ac9310
DO - 10.3847/2041-8213/ac9310
M3 - Article
AN - SCOPUS:85141245472
SN - 2041-8205
VL - 938
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 2
M1 - L10
ER -