Elent\'ari: A $z\sim3.3$ Proto-Supercluster in COSMOS

TL;DR

This paper identifies and characterizes a proto-supercluster at redshift ~3.3 in the COSMOS field, revealing multiple overdense regions and their potential evolution into a massive supercluster, using deep multi-wavelength data and advanced density mapping techniques.

Contribution

It presents the discovery and detailed analysis of six overdense structures at z~3.2-3.45, including a well-characterized proto-supercluster with extensive spectroscopic confirmation.

Findings

Identification of six overdense structures at z~3.2-3.45

One structure with 80 spectroscopically confirmed members

Estimated mass of the proto-supercluster is 1.35×10^15 solar masses

Abstract

Motivated by spectroscopic confirmation of three overdense regions in the COSMOS field at $z\sim3.35$, 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 $z\sim1.5-2.0$. These structures contain ten overdense peaks with $>5\sigma$ overdensity separated by up to 70 cMpc, suggestive of a proto-supercluster similar to the Hyperion system at $z\sim2.45$. 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.