scholarly journals The WaZP galaxy cluster sample of the Dark Energy Survey Year 1

2021 ◽  
Author(s):  
M Aguena ◽  
C Benoist ◽  
L N da Costa ◽  
R L C Ogando ◽  
J Gschwend ◽  
...  
Keyword(s):  
Galaxy Cluster ◽  
First Year ◽  
Photometric Redshifts ◽  
Cluster Galaxy ◽  
Photometric Redshift ◽  
Dark Energy Survey ◽  
Density Maps ◽  
South Pole Telescope ◽  
Galaxy Populations ◽  
Energy Survey

Abstract We present a new (2+1)D galaxy cluster finder based on photometric redshifts called Wavelet Z Photometric (wa zp) applied to DES first year (Y1A1) data. The results are compared to clusters detected by the South Pole Telescope (SPT) survey and the redMaPPer cluster finder, the latter based on the same photometric data. wa zp searches for clusters in wavelet-based density maps of galaxies selected in photometric redshift space without any assumption on the cluster galaxy populations. The comparison to other cluster samples was performed with a matching algorithm based on angular proximity and redshift difference of the clusters. It led to the development of a new approach to match two optical cluster samples, following an iterative approach to minimize incorrect associations. The wa zp cluster finder applied to DES Y1A1 galaxy survey (1,511.13 deg2 up to mi = 23 mag) led to the detection of 60,547 galaxy clusters with redshifts 0.05 < z < 0.9 and richness Ngals ≥ 5. Considering the overlapping regions and redshift ranges between the DES Y1A1 and SPT cluster surveys, all sz based SPT clusters are recovered by the wa zp sample. The comparison between wa zp and redMaPPer cluster samples showed an excellent overall agreement for clusters with richness Ngals (λ for redMaPPer) greater than 25 (20), with 95% recovery on both directions. Based on the cluster cross-match we explore the relative fragmentation of the two cluster samples and investigate the possible signatures of unmatched clusters.

scholarly journals Revisiting Abell 2744: a powerful synergy of GLASS spectroscopy and HFF photometry

2015 ◽  
Vol 11 (A29B) ◽  
pp. 776-778
Author(s):  
Xin Wang ◽  
Keyword(s):  
Mass Distribution ◽  
Galaxy Cluster ◽  
Adaptive Mesh ◽  
Field Of View ◽  
Relative Distribution ◽  
Lens Model ◽  
Photometric Redshifts ◽  
Screening Process ◽  
Photometric Redshift ◽  
Extensive Analysis

AbstractWe present new emission line identifications and improve the lensing reconstruction of the mass distribution of galaxy cluster Abell 2744 using the Grism Lens-Amplified Survey from Space (GLASS) spectroscopy and the Hubble Frontier Fields (HFF) imaging. We performed blind and targeted searches for faint line emitters on all objects, including the arc sample, within the field of view (FoV) of GLASS prime pointings. We report 55 high quality spectroscopic redshifts, 5 of which are for arc images. We also present an extensive analysis based on the HFF photometry, measuring the colors and photometric redshifts of all objects within the FoV, and comparing the spectroscopic and photometric redshift estimates. In order to improve the lens model of Abell 2744, we develop a rigorous algorithm to screen arc images, based on their colors and morphology, and selecting the most reliable ones to use. As a result, 25 systems (corresponding to 72 images) pass the screening process and are used to reconstruct the gravitational potential of the cluster pixellated on an adaptive mesh. The resulting total mass distribution is compared with a stellar mass map obtained from the Spitzer Frontier Fields data in order to study the relative distribution of stars and dark matter in the cluster.

scholarly journals Dark Energy Survey Year 1 results: the effect of intracluster light on photometric redshifts for weak gravitational lensing

2019 ◽  
Vol 488 (3) ◽  
pp. 4389-4399 ◽  
Author(s):  
D Gruen ◽  
Y Zhang ◽  
A Palmese ◽  
B Yanny ◽  
V Busti ◽  
...  
Keyword(s):  
Dark Energy ◽  
Gravitational Lensing ◽  
Mass Density ◽  
Percent Level ◽  
Critical Surface ◽  
Photometric Redshifts ◽  
Surface Mass ◽  
Dark Energy Survey ◽  
Intracluster Light ◽  
Energy Survey

Abstract We study the effect of diffuse intracluster light on the critical surface mass density estimated from photometric redshifts of lensing source galaxies, and the resulting bias in a weak lensing measurement of galaxy cluster mass. Under conservative assumptions, we find the bias to be negligible for imaging surveys like the Dark Energy Survey with a recommended scale cut of ≥200 kpc distance from cluster centres. For significantly deeper lensing source galaxy catalogues from present and future surveys like the Large Synoptic Survey Telescope program, more conservative scale and source magnitude cuts or a correction of the effect may be necessary to achieve percent level lensing measurement accuracy, especially at the massive end of the cluster population.

scholarly journals EIGHT NEW MILKY WAY COMPANIONS DISCOVERED IN FIRST-YEAR DARK ENERGY SURVEY DATA

2015 ◽  
Vol 807 (1) ◽  
pp. 50 ◽  
Author(s):  
K. Bechtol ◽  
A. Drlica-Wagner ◽  
E. Balbinot ◽  
A. Pieres ◽  
J. D. Simon ◽  
...  
Keyword(s):  
Dark Energy ◽  
Survey Data ◽  
Milky Way ◽  
First Year ◽  
Dark Energy Survey ◽  
Energy Survey

scholarly journals Infalling groups and galaxy transformations in the cluster A2142

2018 ◽  
Vol 610 ◽  
pp. A82 ◽  
Author(s):  
Maret Einasto ◽  
Boris Deshev ◽  
Heidi Lietzen ◽  
Rain Kipper ◽  
Elmo Tempel ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Galaxy Cluster ◽  
Stellar Populations ◽  
Normal Mixture ◽  
Cluster Galaxy ◽  
X Ray ◽  
Main Cluster ◽  
Formation And Evolution ◽  
Galaxy Populations ◽  
Stellar Masses

Context. Superclusters of galaxies provide dynamical environments for the study of the formation and evolution of structures in the cosmic web from galaxies, to the richest galaxy clusters, and superclusters themselves. Aims. We study galaxy populations and search for possible merging substructures in the rich galaxy cluster A2142 in the collapsing core of the supercluster SCl A2142, which may give rise to radio and X-ray structures in the cluster, and affect galaxy properties of this cluster. Methods. We used normal mixture modelling to select substructure of the cluster A2142. We compared alignments of the cluster, its brightest galaxies (hereafter BCGs), subclusters, and supercluster axes. The projected phase space (PPS) diagram and clustercentric distributions are used to analyse the dynamics of the cluster and study the distribution of various galaxy populations in the cluster and subclusters. Results. We find several infalling galaxy groups and subclusters. The cluster, supercluster, BCGs, and one infalling subcluster are all aligned. Their orientation is correlated with the alignment of the radio and X-ray haloes of the cluster. Galaxy populations in the main cluster and in the outskirts subclusters are different. Galaxies in the centre of the main cluster at the clustercentric distances 0.5 h−1 Mpc (Dc∕Rvir < 0.5, Rvir = 0.9 h−1 Mpc) have older stellar populations (with the median age of 10−11 Gyr) than galaxies at larger clustercentric distances. Star-forming and recently quenched galaxies are located mostly at the clustercentric distances Dc ≈ 1.8 h−1 Mpc, where subclusters fall into the cluster and the properties of galaxies change rapidly. In this region the median age of stellar populations of galaxies is about 2 Gyr. Galaxies in A2142 on average have higher stellar masses, lower star formation rates, and redder colours than galaxies in rich groups. The total mass in infalling groups and subclusters is M ≈ 6 × 1014 h−1 M⊙, that is approximately half of the mass of the cluster. This mass is sufficient for the mass growth of the cluster from redshift z = 0.5 (half-mass epoch) to the present. Conclusions. Our analysis suggests that the cluster A2142 has formed as a result of past and present mergers and infallen groups, predominantly along the supercluster axis. Mergers cause complex radio and X-ray structure of the cluster and affect the properties of galaxies in the cluster, especially at the boundaries of the cluster in the infall region. Explaining the differences between galaxy populations, mass, and richness of A2142, and other groups and clusters may lead to better insight about the formation and evolution of rich galaxy clusters.

scholarly journals Dark Energy Survey Year 1 results: validation of weak lensing cluster member contamination estimates from P(z) decomposition

2019 ◽  
Vol 489 (2) ◽  
pp. 2511-2524 ◽  
Author(s):  
T N Varga ◽  
J DeRose ◽  
D Gruen ◽  
T McClintock ◽  
S Seitz ◽  
...  
Keyword(s):  
Dark Energy ◽  
Decomposition Method ◽  
Weak Lensing ◽  
Cluster Member ◽  
Photometric Redshift ◽  
Cluster Mass ◽  
Dark Energy Survey ◽  
Mass Calibration ◽  
The Masses ◽  
Energy Survey

ABSTRACT Weak lensing source galaxy catalogues used in estimating the masses of galaxy clusters can be heavily contaminated by cluster members, prohibiting accurate mass calibration. In this study, we test the performance of an estimator for the extent of cluster member contamination based on decomposing the photometric redshift P(z) of source galaxies into contaminating and background components. We perform a full scale mock analysis on a simulated sky survey approximately mirroring the observational properties of the Dark Energy Survey Year One observations (DES Y1), and find excellent agreement between the true number profile of contaminating cluster member galaxies in the simulation and the estimated one. We further apply the method to estimate the cluster member contamination for the DES Y1 redMaPPer cluster mass calibration analysis, and compare the results to an alternative approach based on the angular correlation of weak lensing source galaxies. We find indications that the correlation based estimates are biased by the selection of the weak lensing sources in the cluster vicinity, which does not strongly impact the P(z) decomposition method. Collectively, these benchmarks demonstrate the strength of the P(z) decomposition method in alleviating membership contamination and enabling highly accurate cluster weak lensing studies without broad exclusion of source galaxies, thereby improving the total constraining power of cluster mass calibration via weak lensing.

scholarly journals Gas and galaxies in filaments between clusters of galaxies

2018 ◽  
Vol 609 ◽  
pp. A49 ◽  
Author(s):  
V. Bonjean ◽  
N. Aghanim ◽  
P. Salomé ◽  
M. Douspis ◽  
A. Beelen
Keyword(s):  
Formation Rate ◽  
Galaxy Cluster ◽  
Cluster System ◽  
X Rays ◽  
Perfect Agreement ◽  
Photometric Redshift ◽  
The Galaxy ◽  
Multi Wavelength ◽  
Galaxy Populations ◽  
Associated Pair

We have performed a multi-wavelength analysis of two galaxy cluster systems selected with the thermal Sunyaev-Zel’dovich (tSZ) effect and composed of cluster pairs and an inter-cluster filament. We have focused on one pair of particular interest: A399-A401 at redshiftz~ 0.073 seperated by 3 Mpc. We have also performed the first analysis of one lower-significance newly associated pair: A21-PSZ2 G114.09-34.34 atz~ 0.094, separated by 4.2 Mpc. We have characterised the intra-cluster gas using the tSZ signal fromPlanckand, when possible, the galaxy optical and infrared (IR) properties based on two photometric redshift catalogues: 2MPZ and WISExSCOS. From the tSZ data, we measured the gas pressure in the clusters and in the inter-cluster filaments. In the case of A399-A401, the results are in perfect agreement with previous studies and, using the temperature measured from the X-rays, we further estimate the gas density in the filament and findn0= (4.3 ± 0.7) × 10-4cm-3. The optical and IR colour–colour and colour–magnitude analyses of the galaxies selected in the cluster system, together with their star formation rate, show no segregation between galaxy populations, both in the clusters and in the filament of A399-A401. Galaxies are all passive, early type, and red and dead. The gas and galaxy properties of this system suggest that the whole system formed at the same time and corresponds to a pre-merger, with a cosmic filament gas heated by the collapse. For the other cluster system, the tSZ analysis was performed and the pressure in the clusters and in the inter-cluster filament was constrained. However, the limited or nonexistent optical and IR data prevent us from concluding on the presence of an actual cosmic filament or from proposing a scenario.

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