Ly α properties of simulated galaxies in overdense regions: Effects of galactic winds at z gtrsim 6

Abstract

We perform Monte Carlo radiative transfer calculations to model the Ly α properties of galaxies in high-resolution, zoom-in cosmological simulations at z 1/4 6.6. The simulations include both constrained and unconstrained runs, representing, respectively, a highly overdense region and an average field. Different galactic wind models are used in the simulations in order to investigate the effects of these winds on the apparent Ly α properties of galaxies. We find that, for models including galactic winds, the Ly α properties of massive galaxies residing in the overdense region match well recent observations of luminous Ly α emitters (LAEs) at z 1/4 6'7, in terms of apparent Ly α luminosity, Ly α line width, and Ly α equivalent width distributions. Without winds, the same galaxies appear less Ly α bright as a result of both differences in the line profile emerging from galaxies themselves, and, in the distributions of neutral gas in the circumgalactic (CGM) and intergalactic medium (IGM). We also study the relations between apparent Ly α luminosity and various galaxy properties: stellar mass, star formation rate (SFR), and host haloe mass. At fixed haloe mass, the apparent Ly α luminosity of galaxies appears to depend on the large-scale environment while this is no longer true for galaxies at a given stellar mass or SFR. We provide simple linear fits to these relations that can be used for quickly constructing mock LAE samples from N-body simulations. Our results suggest that the observed luminous LAEs at z 1/4 6.6 are hosted by sim 10 12, h -1, mathrmM-odot, dark matter haloes, residing in large, overdense ionized regions.