An Empirical Model for the Star Formation History in Dark Matter Halos

TL;DR

This paper presents an empirical model linking star formation rates in dark matter halos to galaxy observations across redshifts, revealing a need for star formation enhancement in low-mass halos at high redshift, which challenges standard feedback models.

Contribution

It introduces an empirical approach to infer star formation histories in halos, highlighting a redshift-dependent enhancement in low-mass halos not predicted by existing models.

Findings

Star formation in high-mass halos is boosted at high redshift.

Low-mass halos ($<10^{11}M_{ m sun}$) have enhanced star formation rates above redshift 2.

Predictions include old stellar populations in dwarf galaxies and steep high-redshift stellar mass functions.

Abstract

We develop an empirical approach to infer the star formation rate in dark matter halos from the galaxy stellar mass function (SMF) at different redshifts and the local cluster galaxy luminosity function (CGLF), which has a steeper faint end relative to the SMF of local galaxies. As satellites are typically old galaxies which have been accreted earlier, this feature can cast important constraint on the formation of low-mass galaxies at high-redshift. The evolution of the SMFs suggests the star formation in high mass halos ($>10^{12}M_{\odot}h^{-1}$) has to be boosted at high redshift beyond what is expected from a simple scaling of the dynamical time. The faint end of the CGLF implies a characteristic redshift $z_c\approx2$ above which the star formation rate in low mass halos with masses $< 10^{11}M_{\odot}h^{-1}$ must be enhanced relative to that at lower z. This is not directly expected from the standard stellar feedback models. Also, this enhancement leads to some interesting predictions, for instance, a significant old stellar population in present-day dwarf galaxies with $M_* < 10^8 M_{\odot}h^{-2}$ and steep slopes of high redshift stellar mass and star formation rate functions.