Elentári: A $z\sim 3.3$ Proto-Supercluster in COSMOS

Abstract

Motivated by spectroscopic confirmation of three overdense regions in the COSMOS field at $z\sim 3.35$, we analyze the uniquely deep multi-wavelength photometry and extensive spectroscopy available in the field to identify any further related structure. We construct a three dimensional density map using the Voronoi tesselation Monte Carlo method and find additional regions of significant overdensity. Here we present and examine a set of six overdense structures at $3.20<z<3.45$ in the COSMOS field, the most well characterized of which, PCl~J0959+0235, has 80 spectroscopically confirmed members and an estimated mass of $1.35\times 10^{15}$~M${}_{\odot }$, and is modeled to virialize at $z\sim 1.5-2.0$. These structures contain ten overdense peaks with $>5\ddot{I}ƒ$ overdensity separated by up to 70 cMpc, suggestive of a proto-supercluster similar to the Hyperion system at $z\sim 2.45$. Upcoming photometric surveys with JWST such as COSMOS-Web, and further spectroscopic follow-up will enable more extensive analysis of the evolutionary effects that such an environment may have on its component galaxies at these early times.

Accepted for publication in MNRAS. 7 pages, 3 figures, 3 tables