On the stunning abundance of super-early, luminous galaxies revealed by JWST

The earliest JWST observations have revealed an unexpected abundance of super-early (z > 10), massive (M-* approximate to 10(9) M-circle dot) galaxies at the bright-end (M-UV approximate to -21) of the ultraviolet luminosity function (UV LF). We present a minimal physical model that explains the observed galaxy abundance at z = 10-14. The model primarily combines (i) the halo mass function, with (ii) an obscured star formation fraction prescription that is consistent with findings of the ALMA REBELS dusty galaxy survey. It has been successfully tested on well-known UV LFs up to z = 7. We argue that the weak evolution from z = 7 to z approximate to 14 of the LF bright-end can arise from a conspiracy between a decreasing dust attenuation, making galaxies brighter, that almost exactly compensates for the increasing shortage of their host halos. Our minimal model naturally reproduces the z = 10-14 LF if galaxies at z greater than or similar to 11 contain a negligible amounts of dust. We speculate that dust could have been efficiently ejected during the very first phases of galaxy build-up.

Automated summary

The earliest observations from JWST have discovered an unexpected abundance of super-early, massive galaxies at high redshifts. A minimal physical model combining the halo mass function and an obscured star formation fraction prescription can explain this abundance. The model has been tested on UV luminosity functions and suggests that dust attenuation and host halo shortage may be responsible for the faint evolution of the bright-end of the luminosity function.