The Evolution of Star Formation Rate Density of Galaxies

J Wirsich

doi:10.11648/j.ajmp.20211001.11

Abstract

We present a semi-analytical calculation of the global star formation density (SFD) by using the well constrained cold dark matter (CDM) halo mass function. Both, halo masses MH(z) and stellar masses M*(z) are taken from observations of Lyα emitter (LAEs) and/or Lyman break galaxies (LBGs). Most of them, spectroscopically selected, are characterized by high star formation rates. The view of galaxy formation is mainly based on the hierarchical (“botton-up”) cold dark matter model for structure formation. We have used the connection between the halo mass and the star formation rate in galaxies of the halo mass MH at redshift z. Our model has the advantage that we are able to calculate the global star formation rate ρ*(z) (in Mʘy-1Mpc-3) by a closed equation. All parameters (MH; M* and n) have a well-defined physical meaning. From the CDM spectrum, the power law index of the halo mass function is well constrained. Our results are compiled in Table 1 and Figure 1. Here our results are compared with observations and hydrodynamical simulations. The physical meaning of the evolution of comoving cosmic star density as a function of redshift with three epochs is discussed. We find a good agreement between the SFD inferred from observations and our model in the range of redshifts z = 0 - 7.

Highlights

Galaxies formed at high redshifts play an important role in understanding about first stars and galaxies lighting up in an expanding Universe
The solid line is from Pillepich et al [20]. of 0.5M y−1, we find a stellar mass of 2 × 108M at z = 0 Open circles are from this work
By using the angular correlation technique for virial dark matter halos, they found that the agreement is best if galaxies in the BM, BX and Lyman break galaxies (LBGs) samples are associated with halos of mass MH ∼ 1012.1, 1012.0 and 1011.5M, respectively [37]

Summary

Introduction

Galaxies formed at high redshifts play an important role in understanding about first stars and galaxies lighting up in an expanding Universe. E.g. observations at redshift z ∼ 6 corresponds to 90 % of the age of the Universe. The redshifts of galaxies are inferred either through a search for Lyman-emission lines (Lymanα emitter) (LAEs) or through a search for a spectral break associated with the absorption of intervening hydrogen (Lyman break galaxies) (LBGs) [1, 2]. The LAEs at high redshift are viewed as being main progenitors of our Galaxy. Large Lyα blobs with filamentary structure have halos with a mass of MH ≈ 1012M at redshift z ∼ 2 - 3 [3]. The LBGs are not the first generation objects, the LBGs having experienced metal enrichment from previous stellar generation [4]

Results

Discussion

Conclusion