21SSD: a public database of simulated 21-cm signals from the epoch of
  reionization
  The 21-cm signal from the Epoch of Reionization (EoR) is expected to be
detected in the next few years, either with existing instruments or by the
upcoming SKA and HERA projects. In this context there is a pressing need for
publicly available high-quality templates covering a wide range of possible
signals. These are needed both for end-to-end simulations of the up-coming
instruments, as well as to develop signal analysis methods. In this work we
present such a set of templates, publicly available, for download at
https://21ssd.obspm.fr/. The database contains 21-cm brightness temperature
lightcones at high and low resolution, and several derived statistical
quantities for 45 models spanning our choice of 3D parameter space. These data
are the result of fully coupled radiative hydrodynamic high resolution
($1024^3$) simulations performed with the LICORICE code. Both X-ray and Lyman
line transfer is performed to account for heating and Wouthuysen-Field coupling
fluctuations. We also present a first exploitation of the data using the power
spectrum and the Pixel Distribution Function (PDF) as functions of redshifts,
computed from lightcone data. We analyse how these two quantities behave when
varying the model parameters while taking into account the thermal noise
expected of a typical SKA survey. Finally, we show that the power spectrum and
the PDF have different -- and to some extent complementary -- abilities to
distinguish between different models. This opens the door to formulating an
optimal sampling of the parameter space, dependant on the chosen diagnostics.
