Abstract

Protoclusters are responsible for more than 20 per cent of the cosmic star formation at z>2, also considered as places where the first galaxies and cosmic structures have formed, playing a pivotal role in the reionization and episodic star formation events in the Universe. Despite its importance, however, its study has been severely limited by several critical challenges, in a large part due to inhomogeneities between the studies. I will focus, in particular, the diversity in the volume used to define protoclusters, and its impact on the estimation of their properties. We tackle the issue using the new hydrodynamical simulations of FLAMINGO project. Its large box size of up to 2.8cGpc on a side enables a first reliable statistical analysis of the rarest population in the Universe. The predicted star-formation history is in a good agreement with observations, unlike most of the previous simulation results. I will present a comparison of the number density between the model prediction and recent JWST observations, and discuss its implication in connection to the definition of protoclusters.