First Light And Reionisation Epoch Simulations (FLARES) V: The redshift
  frontier
  The James Webb Space Telescope (JWST) is set to transform many areas of
astronomy, one of the most exciting is the expansion of the redshift frontier
to $z>10$. In its first year alone JWST should discover hundreds of galaxies,
dwarfing the handful currently known. To prepare for these powerful
observational constraints, we use the First Light And Reionisation Epoch
(FLARES) simulations to predict the physical and observational properties of
the $z>10$ population of galaxies accessible to JWST. This is the first time
such predictions have been made using a hydrodynamical model validated at low
redshift. Our predictions at $z=10$ are broadly in agreement with current
observational constraints on the far-UV luminosity function and UV continuum
slope $\beta$, though the observational uncertainties are large. We note
tension with recent constraints $z\sim 13$ from Harikane et al. 2022 - compared
to these constraints, FLARES predicts objects with the same space density
should have an order of magnitude lower luminosity, though this is mitigated
slightly if dust attenuation is negligible in these systems. Our predictions
suggest that in JWST's first cycle alone, around $600$ galaxies should be
identified at $z>10$, with the first small samples available at $z>13$.
