Abstract
Properties of galaxies vary systematically with the mass of their parent dark matter halos. This basic galaxy-halo connection shows a fair amount of scatter whose origin is not fully understood. Here, we study how differences in the halo assembly history affect central galaxies in low-mass (M halo < 10 12 M o ) halos at z = 2-6 with the help of the MassiveFIRE suite of cosmological simulations. In contrast to previous works that tie galaxy properties to halo concentration and halo-formation redshift, we focus on halo growth rate as a measure of assembly history. We find that, at fixed halo mass, faster-growing halos tend to have lower stellar masses and higher star formation rates (SFRs) per unit stellar mass but similar overall SFRs. We provide a simple explanation for these findings with the help of an analytic model that captures approximately the behavior of our hydrodynamical simulations. Specifically, among halos of a given current mass, quickly growing halos have lower stellar masses (and thus higher specific SFRs) because they were less massive and had comparably lower cold-gas masses and SFRs in the past than slowly growing halos. By combining these findings with estimates for the scatter of the halo growth rate, we show that variations in growth rate at fixed halo mass may largely explain the scatter of the stellar mass-halo mass relation. In contrast, halo growth variations likely play only a minor role in the scatter of the star-forming sequence in low-mass galaxies.
| Original language | English (US) |
|---|---|
| Article number | L21 |
| Journal | Astrophysical Journal Letters |
| Volume | 871 |
| Issue number | 2 |
| DOIs | |
| State | Published - Feb 1 2019 |
Funding
R.F. acknowledges financial support from the Swiss National Science Foundation (grant No. 157591). C.A.F.G. was supported by NSF through grants AST-1412836, AST- 1517491, AST-1715216, and CAREER award AST-1652522, by NASA through grant NNX15AB22G, and by a Cottrell Scholar Award from the Research Corporation for Science Advancement. The authors would like to thank the referee for valuable comments that improved the quality of the manuscript. The authors also thank Onur \u00C7atmabacak for providing halo catalogs for two dark-matter-only simulations used in this Letter. R.F. acknowledges financial support from the Swiss National Science Foundation (grant No. 157591). C.A.F.G. was supported by NSF through grants AST-1412836, AST-1517491, AST-1715216, and CAREER award AST-1652522, by NASA through grant NNX15AB22G, and by a Cottrell Scholar Award from the Research Corporation for Science Advancement. D.K. was supported by NSF grant AST-1715101 and the Cottrell Scholar Award from the Research Corporation for Science Advancement. This research was supported in part by the National Science Foundation under grant No. NSF PHY-1748958. Simulations were run with resources provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center, proposal SMD-14-5492. Additional computing support was provided by HEC allocations SMD-14-5189, SMD-15-5950, by NSF XSEDE allocations AST120025, AST150045, by allocations s697, s698 at the Swiss National Supercomputing center, and by S3IT resources at the University of Zurich. This work made extensive use of the NASA Astrophysics Data System and arXiv.org preprint server.
Keywords
- galaxies: dwarf
- galaxies: evolution
- galaxies: halos
- galaxies: star formation
- galaxies: stellar content
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science