Monsters in the Dark: Predictions for Luminous Galaxies in the Early Universe from the BlueTides Simulation

TL;DR

This study uses the BlueTides simulation to predict the abundance and properties of luminous galaxies at redshifts above 10, aligning with recent observations and forecasting future survey capabilities.

Contribution

It provides the first detailed predictions of the population of bright galaxies at z > 10 using a large cosmological simulation, matching recent observations and forecasting future detections.

Findings

BlueTides predicts ~30 galaxies at M_UV ≈ -22 at z=11.

The probability of observing GN-z11 in current surveys is ~13%.

Future WFIRST surveys could detect ~1000 such galaxies beyond z=11.

Abstract

Using deep Hubble and Spitzer observations Oesch et al. (2016) have identified a bright ($M_{\rm UV}\approx -22$) star forming galaxy candidate at $z \approx 11$. The presence of GN-$z11$ implies a number density $\sim 10^{-6}\,{\rm Mpc^{-3}}$, roughly an order of magnitude higher than the expected value based on extrapolations from lower redshift. Using the unprecedented volume and high resolution of the BlueTides cosmological hydrodynamical simulation, we study the population of luminous rare objects at $z > 10$. The luminosity function in BlueTides implies an enhanced number of massive galaxies, consistent with the observation of GN-$z11$. We find about 30 galaxies at $M_{\rm UV}\approx -22$ at $z = 11$ in the BlueTides volume, including a few objects about 1.5 magnitudes brighter. The probability of observing GN-$z11$ in the volume probed by Oesch et al. (2016) is $\sim 13$ per cent. The predicted properties of the rare bright galaxies at $z = 11$ in BlueTides closely match those inferred from the observations of GN-$z11$. BlueTides predicts a negligible contribution from faint AGN in the observed SED. The enormous increase in volume surveyed by WFIRST will provide observations of $\sim1000$ galaxies with $M_{\rm UV} < -22$ beyond $z = 11$ out to $z = 13.5$.