We introduce the BlueTides simulation and report initial results for the luminosity functions of the first galaxies and AGN , and their contribution to reionization .
BlueTides was run on the BlueWaters cluster at NCSA from z = 99 to z = 8.0 and includes 2 \times 7040 ^ { 3 } particles in a 400 h ^ { -1 } Mpc per side box , making it the largest hydrodynamic simulation ever performed at high redshift .
BlueTides includes a pressure-entropy formulation of smoothed particle hydrodynamics , gas cooling , star formation ( including molecular hydrogen ) , black hole growth and models for stellar and AGN feedback processes .
The star formation rate density in the simulation is a good match to current observational data at z \sim 8 - 10 .
We find good agreement between observations and the predicted galaxy luminosity function in the currently observable range -18 \leq M _ { \mathrm { U } V } \leq - 22.5 with some dust extinction required to match the abundance of brighter objects .
BlueTides implements a patchy reionization model that produces a fluctuating UV background .
BlueTides predicts number counts for galaxies fainter than current observational limits which are consistent with extrapolating the faint end slope of the luminosity function with a power law index \alpha \sim - 1.8 at z \sim 8 and redshift dependence of \alpha \sim ( 1 + z ) ^ { -0.4 } .
The AGN population has a luminosity function well fit by a power law with a slope \alpha \sim - 2.4 that compares favourably with the deepest CANDELS-Goods fields .
We investigate how these luminosity functions affect the progress of reionization , and find that a high Lyman- \alpha escape fraction ( f _ { \mathrm { esc } } \sim 0.5 ) is required if galaxies dominate the ionising photon budget during reionization .
Smaller galaxy escape fractions imply a large contribution from faint AGN ( down to M _ { \mathrm { UV } } = -12 ) which results in a rapid reionization , disfavoured by current observations .