$Spitzer$-selected $z>1.3$ protocluster candidates in the LSST Deep Drilling Fields

Abstract

We have identified 189 candidate $z>1.3$ protoclusters and clusters in the LSST Deep Drilling Fields. This sample will enable the measurement of the metal enrichment and star formation history of clusters during their early assembly period through the direct measurement of the rate of supernovae identified through the LSST. The protocluster sample was selected from galaxy overdensities in a $Spitzer$/IRAC colour-selected sample using criteria that were optimised for protocluster purity using a realistic lightcone. Our tests reveal that $60-80\%$ of the identified candidates are likely to be genuine protoclusters or clusters, which is corroborated by a $\sim 4\sigma$ stacked X-ray signal from these structures. We provide photometric redshift estimates for 47 candidates which exhibit strong peaks in the photo-$z$ distribution of their candidate members. However, the lack of a photo-$z$ peak does not mean a candidate is not genuine, since we find a stacked X-ray signal of similar significance from both the candidates that exhibit photo-$z$ peaks and those that do not. Tests on the lightcone reveal that our pursuit of a pure sample of protoclusters results in that sample being highly incomplete ($\sim 4\%$) and heavily biased towards larger, richer, more massive, and more centrally concentrated protoclusters than the total protocluster population. Most ($\sim 75\%$) of the selected protoclusters are likely to have a maximum collapsed halo mass of between $10^{13}-10^{14}$ M${}_{\odot }$, with only $\sim 25\%$ likely to be collapsed clusters above $10^{14}$ M${}_{\odot }$. However, the aforementioned bias ensures our sample is $\sim 50\%$ complete for structures that have already collapsed into clusters more massive than $10^{14}$ M${}_{\odot }$.

18 pages, 14 figures

References in corpus (20)

• EAZY: A Fast, Public Photometric Redshift Code
• The Angular Clustering of Distant Galaxy Clusters
• Why z > 1 radio-loud galaxies are commonly located in proto-clusters
• Stellar mass function of cluster galaxies at z $\sim$ 1.5: evidence for reduced quenching efficiency at high redshift
• An early phase of environmental effects on galaxy properties unveiled by near-infrared spectroscopy of protocluster galaxies at z>2
• The Absence of an Environmental Dependence in the Mass-Metallicity Relation at z=2
• Metal deficiency in cluster star-forming galaxies at z=2
• Characterising and Identifying Galaxy Protoclusters
• The GOGREEN and GCLASS Surveys: First Data Release
• Spectroscopic confirmation of a mature galaxy cluster at redshift two
• Galaxy evolution in protoclusters
• The XMM-SERVS survey: XMM-Newton point-source catalogs for the W-CDF-S and ELAIS-S1 fields
• Enhanced Star Formation of Less Massive Galaxies in a Proto-Cluster at z=2.5
• The X-CLASS survey: A catalogue of 1646 X-ray-selected galaxy clusters up to z$\sim$1.5
• A Spitzer survey of Deep Drilling Fields to be targeted by the Vera C. Rubin Observatory Legacy Survey of Space and Time
• Candidate Clusters of Galaxies at $z>1.3$ Identified in the Spitzer SPT Deep Field Survey
• Evidence for gas-phase metal deficiency in massive protocluster galaxies at z~2.2
• The role of environment in galaxy evolution in the SERVS Survey I: density maps and cluster candidates
• Photometric Redshifts in the W-CDF-S and ELAIS-S1 Fields Based on Forced Photometry from 0.36 -- 4.5 Microns
• A Multi-Band Forced-Photometry Catalog in the ELAIS-S1 Field

Cited by in corpus (2)

• Fueling and feedback mechanisms at the nodes of the cosmic web
• Euclid: A blue galaxy population and a brightest cluster galaxy in the making in a $z\sim 1.74$ MaDCoWS2 galaxy cluster candidate