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Title: Molecular hydrogen regulated star formation in cosmological smoothed particle hydrodynamics simulations

Some observations have shown that star formation (SF) correlates tightly with the presence of molecular hydrogen (H{sub 2}); therefore, it is important to investigate its implication on galaxy formation in a cosmological context. In the present work, we implement a sub-grid model (hereafter H{sub 2}-SF model) that tracks the H{sub 2} mass fraction within our cosmological smoothed particle hydrodynamics code GADGET-3 by using an equilibrium analytic model of Krumholz et al. This model allows us to regulate the SF in our simulation by the local abundance of H{sub 2} rather than the total cold gas density, which naturally introduces the dependence of SF on metallicity. We investigate the implications of the H{sub 2}-SF model on galaxy population properties, such as the stellar-to-halo mass ratio (SHMR), baryon fraction, cosmic star formation rate density (SFRD), galaxy specific SFR, galaxy stellar mass functions (GSMF), and Kennicutt-Schmidt (KS) relationship. The advantage of our work over the previous ones is having a large sample of simulated galaxies in a cosmological volume from high redshift to z = 0. We find that low-mass halos with M {sub DM} < 10{sup 10.5} M {sub ☉} are less efficient in producing stars in the H{sub 2}-SF model atmore » z ≥ 6, which brings the simulations into better agreement with the observational estimates of the SHMR and GSMF at the low-mass end. This is particularly evident by a reduction in the number of low-mass galaxies at M {sub *} ≤ 10{sup 8} M {sub ☉} in the GSMF. The overall SFRD is also reduced at high z in the H{sub 2} run, which results in slightly higher SFRD at low redshift due to more abundant gas available for SF at later times. This new H{sub 2} model is able to reproduce the empirical KS relationship at z = 0 naturally, without the need for setting its normalization by hand, and overall it seems to have more advantages than the previous pressure-based SF model.« less
Authors:
; ;  [1] ;  [2]
  1. Department of Physics and Astronomy, University of Nevada Las Vegas, 4505 S. Maryland Pkwy, Box 454002, Las Vegas, NV 89154-4002 (United States)
  2. Department of Physics and Astronomy, University of Kentucky, Lexington, KY (United States)
Publication Date:
OSTI Identifier:
22348242
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 780; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BARYONS; DENSITY; EQUILIBRIUM; GALAXIES; HYDRODYNAMICS; HYDROGEN; LUMINOSITY; MASS; METALLICITY; RED SHIFT; REDUCTION; SIMULATION; STARS