The Evolution of 21-cm Structure (EOS): public, large-scale simulations
  of Cosmic Dawn and Reionization
  We introduce the Evolution of 21-cm Structure (EOS) project: providing
periodic, public releases of the latest cosmological 21-cm simulations. 21-cm
interferometry is set to revolutionize studies of the Cosmic Dawn (CD) and
epoch of reionization (EoR), eventually resulting in 3D maps of the first
billion years of our Universe. Progress will depend on sophisticated data
analysis pipelines, which are in turn tested on large-scale mock observations.
Here we present the 2016 EOS data release, consisting of the largest (1.6 Gpc
on side with a 1024^3 grid), public 21-cm simulations of the CD and EoR. We
include calibrated, sub-grid prescriptions for inhomogeneous recombinations and
photo-heating suppression of star formation in small mass galaxies. We present
two simulation runs that approximately bracket the contribution from faint
unseen galaxies. From these two extremes, we predict that the duration of
reionization (defined as a change in the mean neutral fraction from 0.9 to 0.1)
should be between 2.7 < Delta z < 5.7. The large-scale 21-cm power during the
advanced EoR stages can be different by up to a factor of ~10, depending on the
model. This difference has a comparable contribution from: (i) the typical bias
of sources; and (ii) a more efficient negative feedback in models with an
extended EoR driven by faint galaxies. We also make detectability forecasts.
With a 1000h integration, HERA and SKA1-low should achieve a signal-to-noise of
~few-hundreds throughout the EoR/CD, while in the maximally optimistic scenario
of perfect foreground cleaning, all instruments should make a statistical
detection of the cosmic signal. We also caution that our ability to clean
foregrounds determines the relative performance of narrow/deep vs. wide/shallow
surveys expected with SKA1. Our 21-cm power spectra, simulation outputs and
visualizations are publicly available.
