Kavli Affiliate: Kohei Inayoshi
| First 5 Authors: Maximilien Franco, Maximilien Franco, , ,
| Summary:
We present measurements of the rest-frame ultraviolet luminosity function
(UVLF) in three redshift bins over $zsim5.5$-14 from the JWST COSMOS-Web
survey. Our samples, selected using the dropout technique in the HST/ACS F814W,
JWST/NIRCam F115W, and F150W filters, contain a total of 3099 galaxies spanning
a wide luminosity range from faint ($M_rm UVsim-19$ mag) to bright ($M_rm
UVsim-22.5$ mag). The galaxies are undergoing rapid star formation, with blue
stellar populations. Surprisingly, their median UV spectral slope $beta$ does
not evolve at $z>8$, suggesting minimal dust, or physical separation of dust
and star formation at early epochs. The measured UVLF exhibits an excess at the
bright-end ($M_rm UV<-21$ mag) compared to pre-JWST empirical results and
theoretical predictions of an evolving Schechter function, with the excess
beginning at $zsim9$ and becoming increasingly prominent toward $zsim12$. Our
analysis suggests that reproducing the observed abundance of UV-bright galaxies
at high redshift requires a combination of physical processes, including
elevated star formation efficiencies, moderate levels of stochasticity in
galaxy luminosities, and minimal dust attenuation.
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