The existence of massive quiescent galaxies at high redshifts can put strong constraints on galaxy formation theories, as there is little cosmic time available for such matured systems to develop by the observed epoch. We will conduct this experiment at z=5.2–5.3 that can be probed by ground-based observations, using medium-band filters K3 and K4 on MOIRCS. We propose to search for such massive galaxies associated with proto-clusters located at HDF850.1 (z=5.18) and GN10(z=5.30). By targeting this most overdense region where galaxies are expected to form and grow earlier and faster in a biased manner, the probability of finding such massive monsters at these high redshifts can be maximized. We can also quantify the bias/acceleration of galaxy formation in overdense regions in the early Universe. Massive galaxy candidates, if discovered, will serve as excellent spectroscopic targets for JWST to characterize their properties such as accurate stellar masses and ages to put strong constraints on the initial onset of star formation beyond the reionization epoch. This is a part of the pilot survey of the RubyRush program, targeting known overdense regions, and is complementary to the narrower, general field JWST programs.
This document was translated from LATEX by HEVEA.