Physics of star formation history and the luminosity function of galaxies therefrom

TL;DR

This paper presents a gravitational collapse model within the b4CDM framework that accurately reproduces the star formation history, reionization, and galaxy luminosity function, highlighting the importance of physical conditions and halo mass dependence.

Contribution

It introduces a simple yet effective gravitational collapse model that matches key cosmic observations, emphasizing the role of physical conditions and halo mass in star formation efficiency.

Findings

Reproduces star formation and reionization histories with high accuracy.

Predicts the luminosity function cutoff at ^{10.7}L_\u209c, consistent with observations.

Shows star formation efficiency peaks at ^{12}M_\u209c halo mass.

Abstract

We show that the star formation history, the reionization history and the present luminosity function of galaxies are reproduced in a simple gravitational collapse model within the $\Lambda$CDM regime to almost a quantitative accuracy, when the physical conditions, the Jeans criterion and the cooling process, are taken into account. Taking a reasonable set of the model parameters, the reionisation takes place sharply at around redshift $1+z\simeq 7.5$, and the resulting luminosity function turns off at $L\simeq 10^{10.7}L_\odot$, showing the consistency between the star formation history and the reionisation of the Universe. The model gives the total amount of stars $\Omega_\mathrm{star}=0.004$ in units of the critical density compared to the observation $0.0044$ with the recycling factor $1.6$ included. In order to account for the observed star formation rate and the present luminosity function, the star formation efficiency is not halo mass independent but becomes maximum at the halo mass $\simeq 10^{12}M_\odot$ and is suppressed for both smaller and larger mass haloes.