"Observing and Analyzing" Images From a Simulated High Redshift Universe

TL;DR

This study uses hydrodynamical simulations and synthetic observations to analyze the evolution of galaxy UV luminosity functions at high redshift, providing predictions consistent with current data and insights for future space telescopes.

Contribution

It introduces a comprehensive simulation and observational pipeline to study high-redshift galaxy luminosity functions, including effects of dust, PSF, and zodiacal background, with predictions for JWST.

Findings

Faint-end slope alpha evolves as -1.16 - 0.12z from z~4.5 to 7.7

Alpha shows shallower evolution at higher redshifts (z~6 to 10.4)

Model overproduces faint galaxies, but dust extinction reduces discrepancy

Abstract

We investigate the high-redshift evolution of the restframe UV-luminosity function (LF) of galaxies via hydrodynamical cosmological simulations, coupled with an emulated observational astronomy pipeline that provides a direct comparison with observations. We do this by creating mock images and synthetic galaxy catalogs of approximately 100 square arcminute fields from the numerical model at redshifts ~ 4.5 to 10.4. We include the effects of dust extinction and the point spread function (PSF) for the Hubble WFC3 camera for comparison with space observations. We also include the expected zodiacal background to predict its effect on space observations, including future missions such as the James Webb Space Telescope (JWST). When our model catalogs are fitted to Schechter function parameters, we predict that the faint-end slope alpha of the LF evolves as alpha = -1.16 - 0.12 z over the redshift range z ~ 4.5 to 7.7, in excellent agreement with observations from e.g., Hathi et al. (2010). However, for redshifts z ~ 6 to 10.4, alpha(z) appears to display a shallower evolution, alpha = -1.79 - 0.03 z. Augmenting the simulations with more detailed physics - specifically stellar winds and supernovae (SN) - produces similar results. The model shows an overproduction of galaxies, especially at faint magnitudes, compared with the observations, although the discrepancy is reduced when dust extinction is taken into account.