The Photometric Properties of Galaxies in the Early Universe

TL;DR

This paper uses the BlueTides simulation to predict the photometric properties of early universe galaxies, examining how modeling assumptions impact observable quantities crucial for understanding galaxy formation during reionisation.

Contribution

It provides detailed predictions of galaxy photometric properties at high redshift and analyzes the effects of different modeling assumptions on these properties.

Findings

Nebular emission can contribute up to 50% of R-band luminosity at z=8.

Choice of stellar population synthesis model can alter Lyman continuum production by a factor of 2.

Model assumptions significantly affect the interpretation of high-redshift galaxy observations.

Abstract

We use the large cosmological hydro-dynamic simulation BlueTides to predict the photometric properties of galaxies during the epoch of reionisation ($z=8-15$). These properties include the rest-frame UV to near-IR broadband spectral energy distributions, the Lyman continuum photon production, the UV star formation rate calibration, and intrinsic UV continuum slope. In particular we focus on exploring the effect of various modelling assumptions, including the assumed choice of stellar population synthesis model, initial mass function, and the escape fraction of Lyman continuum photons, upon these quantities. We find that these modelling assumptions can have a dramatic effect on photometric properties leading to consequences for the accurate determination of physical properties from observations. For example, at $z=8$ we predict that nebular emission can account for up-to $50\%$ of the rest-frame $R$-band luminosity, while the choice of stellar population synthesis model can change the Lyman continuum production rate up to a factor of $\times 2$.