Protoclusters at z=5.7: A view from the MultiDark galaxies

Abstract

Protoclusters, which will yield galaxy clusters at lower redshift, can provide valuable information on the formation of galaxy clusters. However, identifying progenitors of galaxy clusters in observations is not an easy task, especially at high redshift. Different priors have been used to estimate the overdense regions that are thought to mark the locations of protoclusters. In this paper, we use mimicked Ly$\alpha$-emitting galaxies at $z=5.7$ to identify protoclusters in the MultiDark galaxies, which are populated by applying three different semi-analytic models to the 1 $Gpc{h}^{-1}$ MultiDark Planck2 simulation. To compare with observational results, we extend the criterion 1 (a Ly$\alpha$ luminosity limited sample), to criterion 2 (a match to the observed mean galaxy number density). To further statistically study the finding efficiency of this method, we enlarge the identified protocluster sample (criterion 3) to about 3500 at $z=5.7$ and study their final mass distribution. The number of overdense regions and their selection probability depends on the semi-analytic models and strongly on the three selection criteria (partly by design). The protoclusters identified with criterion 1 are associated with a typical final cluster mass of $2.82\pm 0.92\times 10^{15}{M}_{\odot }$ which is in agreement with the prediction (within $\pm 1\sigma$) of an observed massive protocluster at $z=5.7$. Identifying more protoclusters allows us to investigate the efficiency of this method, which is more suitable for identifying the most massive clusters: completeness ($\mathbb{C}$) drops rapidly with decreasing halo mass. We further find that it is hard to have a high purity ($\mathbb{P}$) and completeness simultaneously.

10 pages, 4 figures, 2 tables, version matched to the publication in MNRAS

References in corpus (16)

• Formation of z ~ 6 quasars from hierarchical galaxy mergers
• LoCuSS: The slow quenching of star formation in cluster galaxies and the need for pre-processing
• Protoclusters associated with z > 2 radio galaxies. I. Characteristics of high redshift protoclusters
• LCDM predictions for galaxy protoclusters I: the relation between galaxies, protoclusters and quasars at z~6
• The Three Hundred Project: Backsplash galaxies in simulations of clusters
• Erratum - The many lives of AGN: cooling flows, black holes and the luminosities and colours of galaxies
• MultiDark-Galaxies: data release and first results
• Mapping and characterisation of cosmic filaments in galaxy cluster outskirts: strategies and forecasts for observations from simulations
• The Three Hundred Project: correcting for the hydrostatic-equilibrium mass bias in X-ray and SZ surveys
• A physical model for the evolving UV luminosity function of high redshift galaxies and their contribution to the cosmic reionization
• Discovery of a Very Large Structure at Z=3.78
• A First Site of Galaxy Cluster Formation: Complete Spectroscopy of a Protocluster at $z=6.01$
• The Three Hundred Project: Ram pressure and gas content of haloes and subhaloes in the phase-space plane
• Discovery of a Proto-cluster Associated with a Ly-$\alpha$ Blob Pair at z=2.3
• The Three Hundred project: shapes and radial alignment of satellite, infalling, and backsplash galaxies
• The Three Hundred Project: the stellar and gas profiles

Cited by in corpus (1)

• The Three Hundred Project: the evolution of physical baryon profiles