http://arxiv.org/abs/2305.01681
Recent observations with the James Webb Space Telescope (JWST) are yielding tantalizing hints of an early population of massive, bright galaxies at $z > 10$, with Atacama Large Millimeter Array (ALMA) observations indicating significant dust masses in place as early as $z\sim 7$. To understand the implications of these observations, we use the DELPHI semi-analytic model that jointly tracks the assembly of dark matter halos and their constituent baryons, including the key processes of dust enrichment. Our model employs only two redshift- and mass-independent free parameters that are tuned against all available galaxy data at $z \sim 5-9$ before it is used to make predictions up to $z \sim 20$. Our key results are: (1) the model progressively under-predicts the observed ultraviolet luminosity function (UV LF) at $z > 12$; observations at $z>16$ lie close to, or even above, a “maximal” model where all available gas is turned into stars; (2) UV selection would miss 34% of the star formation rate density at $z \sim 5$, decreasing to 17% by $z \sim 10$ for bright galaxies with $\rm{M_{UV}} < -19$; (3) the dust mass ($M_d$) evolves with the stellar mass ($M_$) and redshift as $\log(M_d) = 1.194\log(M_) + 0.0975z – 5.433$; (4) the escape fraction of UV photons ($f_{\rm esc}^{\rm UV}$) decreases with increasing mass and star formation rate. At $z \sim 7$, $f_{\rm esc}^{\rm UV} \sim 0.8~(0.1)$ for $M_* \sim 10^9~ (10^{11}) \, M_\odot$ galaxies; (5) the dust temperature increases with stellar mass, ranging between $30-33$ K for $M_* \sim 10^{9-11}M_\odot$ galaxies at $z \sim 7$. Finally, we predict the far infrared (FIR) LF at $z \sim 5-20$, testable with ALMA observations, and caution that spectroscopic redshifts and dust masses must be pinned down before invoking unphysical extrema in galaxy formation models.
V. Mauerhofer and P. Dayal
Thu, 4 May 23
36/60
Comments: N/A