A survey of high-z galaxies: SERRA simulations

We introduce SERRA, a suite of zoom-in high-resolution (1.2 x 10(4) M-circle dot, similar or equal to 25 pc at z = 7.7) cosmological simulations including non-equilibrium chemistry and on-the-fly radiative transfer. The outputs are post-processed to derive galaxy ultraviolet (UV) + far-infrared (FIR) continuum and emission line properties. Results are compared with available multiwavelength data to constrain the physical properties I e.g. star formation rates (SFRs), stellar/gas/dust mass, metallicityl of high-redshift 6 less than or similar to z less than or similar to 15 galaxies. This flagship paper focuses on the z = 7.7 sub-sample, including 202 galaxies with stellar mass 10(7) M-circle dot less than or similar to M-* less than or similar to 5 x 10(10) M-circle dot, and specific star formation rate ranging from sSFR similar to 100 Gyr(-1) in young, low-mass galaxies to similar to 10 Gyr(-1) for older, massive ones. At this redshift, SERRA galaxies are typically bursty, i.e. they are located above the Schmidt-Kennicutt relation by a factor kappa(s) = 3.03(-1.8)(+4.9), consistent with recent findings for [O III] and [C II] emitters at high z. They also show relatively large InfraRed eXcess (IRX = L-FIR/L-UV) values as a result of their compact/clumpy morphology effectively blocking the stellar UV luminosity. Note that this conclusion might be affected by insufficient spatial resolution at the molecular cloud level. We confirm that early galaxies lie on the standard [CII]-SFR relation; their observed L-[OIII]/L-[CII] similar or equal to 1-10 ratios can be reproduced by a part of the SERRA galaxies without the need of a top-heavy initial mass function and/or anomalous C/O abundances. [OI] line intensities are similar to local ones, making ALMA high-z detections challenging but feasible (similar to 6 h for an SFR of 50 M-circle dot yr(-1)).