New survey to map the early universe and predict how galaxies cluster together
A European space telescope called Euclid will soon scan vast regions of the early universe to find thousands of proto-clusters—groups of galaxies still forming together billions of years ago. New simulations show Euclid can reliably detect these structures, giving scientists an unprecedented view of how galaxies organize and evolve, with implications for understanding cosmic structure and large-scale physics.
Originaltitel: Euclid preparation LV. Exploring the properties of proto-clusters in the Simulated Euclid Wide Survey
<p>Galaxy proto-clusters are receiving increased interest since most of the processes shaping the structure of clusters of galaxies and their galaxy population happen at the early stages of their formation. The Euclid Survey will provide a unique opportunity to discover a large number of proto-clusters over a large fraction of the sky (14 500 deg<sup>2</sup>). In this paper, we explore the expected observational properties of proto-clusters in the Euclid Wide Survey by means of theoretical models and simulations. We provide an overview of the predicted proto-cluster extent, galaxy density profiles, mass-richness relations, abundance, and sky-filling as a function of redshift. Useful analytical approximations for the functions of these properties are provided. The focus is on the redshift range z = 1:5 4. In particular we discuss the density contrast with which proto-clusters can be observed against the background in the galaxy distribution if photometric galaxy redshifts are used as supplied by the ESA Euclid mission together with the ground-based photometric surveys. We show that the obtainable detection significance is su fficient to find large numbers of interesting proto-cluster candidates. For quantitative studies, additional spectroscopic follow-up is required to confirm the proto-clusters and establish their richness.</p>