Search

The past decade has been witness to immense progress in the understanding of the early stages of cluster formation both from a theoretical and observational perspective. During this time, samples of forming clusters at higher redshift, termed “proto-clusters”, once comprised of heterogeneous mix of serendipitous detections or detections arising from dedicated searches around rare galaxy populations, have begun to compete with lower-redshift samples both in terms of numbers and in the homogeneity of the detection methods. Much of this progress has come from optical/near-infrared (NIR) imaging and spectroscopic campaigns designed to target large numbers of typical galaxies to exquisite depth. In this poster I will focus on observations from VIMOS on VLT and MOSFIRE/DEIMOS on Keck, which have uncovered a large number of “proto-structures" at 2 < z < 5 that appear to resemble clusters and groups forming in the early universe. I will demonstrate the methods for finding, confirming, and characterizing proto-clusters and proto-groups in our sample. Several case studies of spectroscopically-confirmed massive proto-clusters with a diverse set of properties will be presented. I will finally present constraints on the relationship between star formation rate, stellar mass, and galaxy density at these redshifts., Funded by the US National Science Foundation Grant Number #1908422

The relationship between environment and galaxy evolution remains an open question in the high-redshift universe when clusters are in their early stages, termed “protoclusters”.The past decade has been witness to immense progress in the searching and understanding of the protocluster both from a theoretical and observational perspective.Among these studies, I introduce the Charting Cluster Construction with the VIMOS Ultra-Deep Survey (VUDS) and ORELSE (C3VO) survey, an ongoing spectroscopy campaign with both DEIMOS/Keck and MOSFIRE/Keck, to provide a nearly complete mapping of the five protoclusters at 2 < z < 5detected inthe VIMOS Ultra-Deep Survey (VUDS) fields In this poster, I focus on one of the protocluster PCl J0227-0421 at z=3.3 and the two radio-detect AGNs (RAGNs) newly found in and around it. The three-dimensional overdensity maparound this protocluster was revised using new spectroscopic observations obtained from the Keck/MOSFIRE as part of the C3VO survey and previous spectroscopic data obtained as part of the VIMOS-Very Large Telescope Deep Survey and VUDS. This protocluster is actually embedded in a complex proto-structure that has an estimated total mass of \(\sim2.6\times10^{15}M_\odot\)and contains several overdensity peaks. This is the first time that two RAGNs at low luminosity (\(L_{1.4GHz} \sim10^{25} W\ Hz^{-1}\)) have been found and studied within a high-redshift protostructure.Both RAGNs are hosted by either the brightest or the most massive galaxies in this proto-strucutre, thus being by definition the progenitor of BCGs. However, their hosts show extreme differences in color, indicating that they are dominated by different stellar populations or/and have experienced different evolutionary paths.Meanwhile, one of the RAGN, named "radio-BCG", also the most massive galaxy, resides in the least massive peak in this proto-structure. This is an example of pre-processing that it has formed a considerable fraction of its stellar mass before even entering the main peak. In addition, examining their surrounding environments, neither are coincident with the most locally overdense regions of the proto-structure, lacking any nearby bright companions.Thus, we propose a scenario where merging might have already happened in both cases, which lowered the local density of their surrounding area and boosted their stellar mass.&nbsp