Constraining the Star Formation Histories in Dark Matter Halos: I. Central Galaxies

TL;DR

This paper models the star formation histories of central galaxies within dark matter halos across cosmic time, revealing how star formation rates depend on halo mass and redshift, and aligning with dark matter accretion rates.

Contribution

It introduces a universal formula for the median star formation history of central galaxies based on halo mass, stellar mass, and redshift, integrating observational constraints and halo assembly histories.

Findings

SSFR increases rapidly with redshift for fixed halo mass

Star formation rate peaks at a constant ratio to stellar mass, independent of halo mass

Majority of stars formed in halos of 10^{11.1} to 10^{12.3} solar masses between redshift 0.4 and 1.9

Abstract

Using the self-consistent modeling of the conditional stellar mass functions across cosmic time by Yang et al. (2012), we make model predictions for the star formation histories (SFHs) of {\it central} galaxies in halos of different masses. The model requires the following two key ingredients: (i) mass assembly histories of central and satellite galaxies, and (ii) local observational constraints of the star formation rates of central galaxies as function of halo mass. We obtain a universal fitting formula that describes the (median) SFH of central galaxies as function of halo mass, galaxy stellar mass and redshift. We use this model to make predictions for various aspects of the star formation rates of central galaxies across cosmic time. Our main findings are the following. (1) The specific star formation rate (SSFR) at high $z$ increases rapidly with increasing redshift [$\propto (1+z)^{2.5}$] for halos of a given mass and only slowly with halo mass ($\propto M_h^{0.12}$) at a given $z$, in almost perfect agreement with the specific mass accretion rate of dark matter halos. (2) The ratio between the star formation rate (SFR) in the main-branch progenitor and the final stellar mass of a galaxy peaks roughly at a constant value, $\sim 10^{-9.3} h^2 {\rm yr}^{-1}$, independent of halo mass or the final stellar mass of the galaxy. However, the redshift at which the SFR peaks increases rapidly with halo mass. (3) More than half of the stars in the present-day Universe were formed in halos with $10^{11.1}\msunh < M_h < 10^{12.3}\msunh$ in the redshift range $0.4 < z < 1.9$. (4) ... [abridged]