Confronting predictions of the galaxy stellar mass function with observations at high-redshift

Abstract

We investigate the evolution of the galaxy stellar mass function at high-redshift ($z\ge 5$) using a pair of large cosmological hydrodynamical simulations: {\em MassiveBlack} and {\em MassiveBlack-II}. By combining these simulations we can study the properties of galaxies with stellar masses greater than $10^8{\mathrm{M}}_{\odot }{h}^{-1}$ and (co-moving) number densities of ${\log }_{10}(\varphi [\mathrm{Mp}{\mathrm{c}}^{-3}\mathrm{de}{\mathrm{x}}^{-1}{h}^3])>-8$. Observational determinations of the galaxy stellar mass function at very-high redshift typically assume a relation between the observed UV luminosity and stellar mass-to-light ratio which is applied to high-redshift samples in order to estimate stellar masses. This relation can also be measured from the simulations. We do this, finding two significant differences with the usual observational assumption: it evolves strongly with redshift and has a different shape. Using this relation to make a consistent comparison between galaxy stellar mass functions we find that at $z=6$ and above the simulation predictions are in good agreement with observed data over the whole mass range. Without using the correct UV luminosity and stellar mass-to-light ratio, the discrepancy would be up to two orders of magnitude for large galaxies $>10^{10}{\mathrm{M}}_{\odot }{h}^{-1}$. At $z=5$, however the stellar mass function for low mass $<10^9{\mathrm{M}}_{\odot }{h}^{-1}$ galaxies is overpredicted by factors of a few, consistent with the behaviour of the UV luminosity function, and perhaps a sign that feedback in the simulation is not efficient enough for these galaxies.

7 pages, 4 figures, accepted in MNRAS

References in corpus (6)

• The Hubble Ultra Deep Field
• UV Luminosity Functions at z~4, 5, and 6 from the HUDF and other Deep HST ACS Fields: Evolution and Star Formation History
• Direct cosmological simulations of the growth of black holes and galaxies
• z~7-10 Galaxies in the HUDF and GOODS fields, and their UV Luminosity Functions
• The Stellar Mass Density at z~6 from Spitzer Imaging of i-drop Galaxies
• Predictions for the intrinsic UV continuum properties of star forming galaxies and the implications for inferring dust extinction

Cited by in corpus (7)

• The MassiveBlack-II Simulation: The Evolution of Halos and Galaxies to z~0
• The galaxy stellar mass function at 3.5<z<7.5 in the CANDELS/UDS, GOODS-South, and HUDF fields
• The mass evolution of the first galaxies: stellar mass functions and star formation rates at $4<z<7$ in the CANDELS GOODS-South field
• The properties of the first galaxies in the BLUETIDES simulation
• Simulated star formation rate functions at z~4-7, and the role of feedback in high-z galaxies
• The stellar mass function and star formation rate-stellar mass relation of galaxies at z ~ 4 - 7
• What Do Radio Emission Constraints Tell Us About Little Red Dots as Tidal Disruption Events?