Simulated void galaxies in the standard cold dark matter model

TL;DR

This study uses high-resolution hydrodynamic simulations to analyze galaxy populations in cosmic voids, revealing a significant number of low-luminosity, star-forming dwarf galaxies in underdense regions that align with some observational data.

Contribution

It provides detailed predictions of galaxy properties in voids using advanced simulations, highlighting the prevalence of faint, star-forming dwarf galaxies in these regions.

Findings

Nearly 1300 galaxies identified in the void with ~1 kpc resolution.

Void dwarf galaxies are typically bluer and have higher star formation rates.

A significant population of low-luminosity dwarf galaxies is located in void centers.

Abstract

We analyze a (120 h^{-1} Mpc)^3 adaptive mesh refinement hydrodynamic simulation that contains a higher-resolution 31 x 31 x 35 h^{-3} Mpc subvolume centered on a ~30 Mpc diameter void. Our detailed ~1 kpc resolution allows us to identify 1300 galaxies within this void to a limiting halo mass of ~10^{10} M_sun. Nearly 1000 galaxies are found to be in underdense regions, with 300 galaxies residing in regions less than half the mean density of the simulation volume. We construct mock observations of the stellar and gas properties of these systems, and reproduce the range of colors and luminosities observed in the SDSS for nearby (z < 0.03) galaxies. We find no trends with density for the most luminous (M_r < -18) galaxies, however our dwarf void galaxies (M_r > -16), though they are less reliably resolved, typically appear bluer, with higher rates of star formation and specific star formation and lower mean stellar ages than galaxies in average density environments. We find a significant population of low luminosity (M_r ~ -14) dwarf galaxies that is preferentially located in low density regions and specifically in the void center. This population may help to reduce, but not remove, the discrepancy between the predicted and observed number of void galaxies.