Physical properties of galaxies and the UV Luminosity Function from $z\sim 6$ to $z\sim 14$ in COSMOS-Web

Abstract

We present measurements of the rest-frame ultraviolet luminosity function (UVLF) in three redshift bins over $z\sim 5.5$-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 ($M_{\mathrm{UV}}\sim -19$ mag) to bright ($M_{\mathrm{UV}}\sim -22.5$ 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 ($M_{\mathrm{UV}}<-21$ mag) compared to pre-JWST empirical results and theoretical predictions of an evolving Schechter function, with the excess beginning at $z\sim 9$ and becoming increasingly prominent toward $z\sim 12$. 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.

35 pages, 17 figures, submitted to ApJ

Cited by in corpus (1)

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