Abstract

Protoclusters and overdensities of galaxies at high redshifts are critical for understanding the galaxy formation and the evolution of the Universe, as they account for at least 20 per cent (up to 50 per cent) of the cosmic star formation at z>2. Greatest challenges in studying protoclusters, however, have been inhomogeneities found often times in the literature, arising from different definitions and various selection techniques used to identify such regions from observations. Comparisons with theoretical models are even more complicated, by how to define protoclusters, and by exactly how to mimick the observational selections. In this talk, I will present new results and insights based on a new simulation suite of FLAMINGO project, as well as highlighting important lessons from simulations of the previous generation for protocluster studies. FLAMINGO has unprecedentedly large box size of 2.8cGpc for hydrodynamical cosmological simulations, which must be big enough to contain the rarest, most extreme objects in the Universe, protoclusters, given their expected number densities from observations. Also, we will show how the results compare with newly found protocluster candidates from JWST at z>5, and discuss their implications.