Characterising and Identifying Galaxy Protoclusters

Abstract

We study the characteristics of galaxy protoclusters using the latest L-galaxies semi-analytic model. Searching for protoclusters on a scale of $\sim 10\mathrm{cMpc}$ gives an excellent compromise between the completeness and purity of their galaxy populations, leads to high distinction from the field in overdensity space, and allows accurate determination of the descendant cluster mass. This scale is valid over a range of redshifts and selection criteria. We present a procedure for estimating, given a measured galaxy overdensity, the protocluster probability and its descendant cluster mass for a range of modelling assumptions, particularly taking into account the shape of the measurement aperture. This procedure produces lower protocluster probabilities compared to previous estimates using fixed size apertures. The relationship between AGN and protoclusters is also investigated, and shows significant evolution with redshift; at $z\sim 2$ the fraction of protoclusters traced by AGN is high, but the fraction of all AGN in protoclusters is low, whereas at $z⩾5$ the fraction of protoclusters containing AGN is low, but most AGN are in protoclusters. We also find indirect evidence for the emergence of a passive sequence in protoclusters at $z\sim 2$, and note that a significant fraction of all galaxies reside in protoclusters at $z⩾2$, particularly the most massive.

19 pages, 16 figures, submitted to MNRAS

References in corpus (21)

• The hierarchical formation of the brightest cluster galaxies
• An Observational Determination of the Bolometric Quasar Luminosity Function
• The spin and shape of dark matter haloes in the Millennium simulation of a LambdaCDM universe
• The VIMOS Ultra-Deep Survey: ~10,000 galaxies with spectroscopic redshifts to study galaxy assembly at early epochs 2<z<~6
• A massive proto-cluster of galaxies at a redshift of z {\approx} 5.3
• Quasar Quartet Embedded in Giant Nebula Reveals Rare Massive Structure in Distant Universe
• Protoclusters associated with z > 2 radio galaxies. I. Characteristics of high redshift protoclusters
• The Spiderweb galaxy: a forming massive cluster galaxy at z~2
• Why z > 1 radio-loud galaxies are commonly located in proto-clusters
• LCDM predictions for galaxy protoclusters I: the relation between galaxies, protoclusters and quasars at z~6
• MAHALO Deep Cluster Survey I. Accelerated and enhanced galaxy formation in the densest regions of a protocluster at z=2.5
• The primordial environment of super massive black holes: large scale galaxy overdensities around $z\sim 6$ QSOs with LBT
• Identification of the progenitors of rich clusters and member galaxies in rapid formation at z>2
• A z=2.5 protocluster associated with the radio galaxy MRC 2104-242: star formation and differing mass functions in dense environments
• No overdensity of Lyman Alpha Emitting Galaxies around a quasar at z~5.7
• A proto-cluster at z=2.45
• Rhapsody. I. Structural Properties and Formation History From a Statistical Sample of Re-simulated Cluster-size Halos
• Galaxy formation in the PLANCK cosmology - III. The high-redshift universe
• Discovery of an Overdensity of Lyman-alpha Emitters Around a $\mathrm{z}\sim 4$ QSO with the Large Binocular Telescope
• The candidate cluster and protocluster catalog (CCPC) II: Spectroscopically identified structures spanning 2 < z < 6.6
• Proto-clusters in the Lambda CDM Universe

Cited by in corpus (1)

• The brightest UV-selected galaxies in protoclusters at $z\sim 4$: Ancestors of Brightest Cluster Galaxies?