scholarly journals TheThreeHundred project: backsplash galaxies in simulations of clusters

2020 ◽  
Vol 492 (4) ◽  
pp. 6074-6085 ◽  
Author(s):  
Roan Haggar ◽  
Meghan E Gray ◽  
Frazer R Pearce ◽  
Alexander Knebe ◽  
Weiguang Cui ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Galaxy Cluster ◽  
Recent History ◽  
Cluster Galaxies ◽  
Cluster Centre ◽  
Dynamical State ◽  
History Of ◽  
First Time

ABSTRACT In the outer regions of a galaxy cluster, galaxies either may be falling into the cluster for the first time or have already passed through the cluster centre at some point in their past. To investigate these two distinct populations, we utilize TheThreeHundred project, a suite of 324 hydrodynamical resimulations of galaxy clusters. In particular, we study the ‘backsplash population’ of galaxies: those that have passed within R200 of the cluster centre at some time in their history, but are now outside of this radius. We find that, on average, over half of all galaxies between R200 and 2R200 from their host at $z$ = 0 are backsplash galaxies, but that this fraction is dependent on the dynamical state of a cluster, as dynamically relaxed clusters have a greater backsplash fraction. We also find that this population is mostly developed at recent times ($z$ ≲ 0.4), and is dependent on the recent history of a cluster. Finally, we show that the dynamical state of a given cluster, and thus the fraction of backsplash galaxies in its outskirts, can be predicted based on observational properties of the cluster.

scholarly journals The growth of the red-sequence in clusters since ≃1

2009 ◽  
Vol 5 (H15) ◽  
pp. 88-88
Author(s):  
Roberto P. Muñoz ◽  
L. F. Barrientos ◽  
B. P. Koester ◽  
D. G. Gilbank ◽  
M. D. Gladders ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Clusters ◽  
Evolutionary Model ◽  
Large Ensemble ◽  
Cluster Galaxies ◽  
Nir Imaging ◽  
Measured Change ◽  
First Time ◽  
The Universe ◽  
Red Sequence

AbstractWe use deep nIR imaging of 15 galaxy clusters at z ≃ 1 to study the build-up of the red-sequence in rich clusters since the Universe was half its present age. We measured, for the first time, the luminous-to-faint ratio of red-sequence galaxies at z=1 from a large ensemble of clusters, and found an increase of 100% in the ratio of luminous-to-faint red-sequence galaxies from z=0.45 to 1.0. The measured change in this ratio as function of redshift is well-reproduced by a simple evolutionary model developed in this work, that consists in an early truncation of the star formation for bright cluster galaxies and a delayed truncation for faint cluster galaxies.

scholarly journals The 3XMM/SDSS Stripe 82 Galaxy Cluster Survey – II. X-ray and optical properties of the cluster sample

2019 ◽  
Vol 486 (4) ◽  
pp. 4863-4879 ◽  
Author(s):  
Ali Takey ◽  
Florence Durret ◽  
Isabel Márquez ◽  
Amael Ellien ◽  
Mona Molham ◽  
...  
Keyword(s):  
Optical Properties ◽  
Galaxy Cluster ◽  
X Rays ◽  
Present Sample ◽  
X Ray ◽  
Cluster Galaxies ◽  
Cluster Survey ◽  
Cluster Sample ◽  
Cluster Mass ◽  
First Time

ABSTRACT We present X-ray and optical properties of the optically confirmed galaxy cluster sample from the 3XMM/SDSS Stripe 82 cluster survey. The sample includes 54 galaxy clusters in the redshift range of 0.05–1.2, with a median redshift of 0.36. We first present the X-ray temperature and luminosity measurements that are used to investigate the X-ray luminosity–temperature relation. The slope and intercept of the relation are consistent with those published in the literature. Then, we investigate the optical properties of the cluster galaxies including their morphological analysis and the galaxy luminosity functions (GLFs). The morphological content of cluster galaxies is investigated as a function of cluster mass and distance from the cluster centre. No strong variation of the fraction of early- and late-type galaxies with cluster mass is observed. The fraction of early-type galaxies as a function of cluster radius varies as expected. The individual GLFs of red sequence galaxies were studied in the five ugriz bands for 48 clusters. The GLFs were then stacked in three mass bins and two redshift bins. Twenty clusters of the present sample are studied for the first time in X-rays, and all are studied for the first time in the optical range. Altogether, our sample appears to have X-ray and optical properties typical of ‘average’ cluster properties.

scholarly journals Iron abundance distribution in the hot gas of merging galaxy clusters

2019 ◽  
Vol 629 ◽  
pp. A31 ◽  
Author(s):  
I. Urdampilleta ◽  
F. Mernier ◽  
J. S. Kaastra ◽  
A. Simionescu ◽  
J. de Plaa ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Clear Correlation ◽  
Iron Abundance ◽  
History Of ◽  
Chemical History ◽  
Lower Entropy ◽  
Abundance Profile ◽  
Low Entropy ◽  
First Time ◽  
Good Agreement

We present XMM-Newton/EPIC observations of six merging galaxy clusters and study the distributions of their temperature, iron (Fe) abundance and pseudo-entropy along the merging axis. For the first time, we focused simultaneously, and in a comprehensive way, on the chemical and thermodynamic properties of the newly collided intra cluster medium (ICM). The Fe distribution of these clusters along the merging axis is found to be in good agreement with the azimuthally-averaged Fe abundance profile in typical non-cool-core clusters out to r500. In addition to showing a moderate central abundance peak, though less pronounced than in relaxed systems, the Fe abundance flattens at large radii towards ∼0.2−0.3 Z⊙. Although this shallow metal distribution is in line with the idea that disturbed, non-cool-core clusters originate from the merging of relaxed, cool-core clusters, we find that in some cases, remnants of metal-rich and low entropy cool cores can persist after major mergers. While we obtain a mild anti-correlation between the Fe abundance and the pseudo-entropy in the (lower entropy, K = 200−500 keV cm2) inner regions, no clear correlation is found at (higher entropy, K = 500−2300 keV cm2) outer radii. The apparent spatial abundance uniformity that we find at large radii is difficult to explain through an efficient mixing of freshly injected metals, particularly in systems for which the time since the merger is short. Instead, our results provide important additional evidence in favour of the early enrichment scenario in which the bulk of the metals are released outside galaxies at z >  2−3, and extend it from cool-core and (moderate) non-cool-core clusters to a few of the most disturbed merging clusters as well. These results constitute a first step toward a deeper understanding of the chemical history of merging clusters.

scholarly journals The Three Hundred project: shapes and radial alignment of satellite, infalling, and backsplash galaxies

2020 ◽  
Vol 495 (3) ◽  
pp. 3002-3013 ◽  
Author(s):  
Alexander Knebe ◽  
Matías Gámez-Marín ◽  
Frazer R Pearce ◽  
Weiguang Cui ◽  
Kai Hoffmann ◽  
...  
Keyword(s):  
Dark Matter ◽  
Galaxy Clusters ◽  
Galaxy Cluster ◽  
Cluster Radius ◽  
Dynamical State ◽  
The Galaxy ◽  
Radial Orbit ◽  
Galaxy Halo ◽  
Satellite Galaxies

ABSTRACT Using 324 numerically modelled galaxy clusters, we investigate the radial and galaxy–halo alignment of dark matter subhaloes and satellite galaxies orbiting within and around them. We find that radial alignment depends on distance to the centre of the galaxy cluster but appears independent of the dynamical state of the central host cluster. Furthermore, we cannot find a relation between radial alignment of the halo or galaxy shape with its own mass. We report that backsplash galaxies, i.e. objects that have already passed through the cluster radius but are now located in the outskirts, show a stronger radial alignment than infalling objects. We further find that there exists a population of well radially aligned objects passing very close to the central cluster’s centre that were found to be on highly radial orbit.

scholarly journals The KMOS Galaxy Clusters Project

2014 ◽  
Vol 10 (S311) ◽  
pp. 110-115
Author(s):  
Roger L. Davies ◽  
A. Beifiori ◽  
R. Bender ◽  
M. Cappellari ◽  
J. Chan ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Galaxy Evolution ◽  
Star Formation History ◽  
Cluster Galaxies ◽  
V Band ◽  
Spectral Bands ◽  
Formation History ◽  
The Status ◽  
History Of ◽  
Integral Field

AbstractKMOS is a cryogenic infrared spectrograph fed by twentyfour deployable integral field units that patrol a 7.2 arcminute diameter field of view at the Nasmyth focus of the ESO VLT. It is well suited to the study of galaxy clusters at 1 < z < 2 where the well understood features in the restframe V-band are shifted into the KMOS spectral bands. Coupled with HST imagining, KMOS offers a window on the critical epoch for galaxy evolution, 7-10 Gyrs ago, when the key properties of cluster galaxies were established. We aim to investigate the size, mass, morphology and star formation history of galaxies in the clusters. Here we describe the instrument, discuss the status of the observations and report some preliminary results.

scholarly journals The effect of AGN feedback on Sunyaev-Zeldovich properties of simulated galaxy clusters

2016 ◽  
Vol 12 (S324) ◽  
pp. 237-238
Author(s):  
Dunja Fabjan ◽  
S. Planelles ◽  
S. Borgani ◽  
G. Murante ◽  
E. Rasia ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galaxy Clusters ◽  
State Of The Art ◽  
Galaxy Cluster ◽  
Galactic Nuclei ◽  
Stellar Feedback ◽  
The Galaxy ◽  
History Of ◽  
Hydrodynamical Simulations ◽  
Massive Clusters

AbstractWe studied the imprints that feedback from Active Galactic Nuclei (AGN) leaves on the intracluster plasma during the assembly history of galaxy clusters. To this purpose we used state-of-the-art cosmological hydrodynamical simulations based on an updated version of the Tree-PM SPH GADGET-3 code, comparing three sets of simulations with different prescriptions for the physics of baryons (including AGN and/or stellar feedback). We explore the effect of these different physics, in particular AGN feedback, on IntraCluster medium (ICM) properties observed via Sunyaev-Zel’dovich (SZ) effect using an extended set of galaxy clusters (~100 clusters with M500 masses above 5 × 1013M⊙/h). Some of the main findings are that the scaling relation between the integrated SZ flux and the galaxy cluster total mass is in good accordance with several observed samples, especially for massive clusters, and does not show any clear redshift evolution, with the slope of the relation close to the theoretical one in the AGN feedback case. As for the scatter of this relation, we obtain a mild dependence on the cluster dynamical state.

scholarly journals The search for galaxy cluster members with deep learning of panchromatic HST imaging and extensive spectroscopy

2020 ◽  
Vol 643 ◽  
pp. A177
Author(s):  
G. Angora ◽  
P. Rosati ◽  
M. Brescia ◽  
A. Mercurio ◽  
C. Grillo ◽  
...  
Keyword(s):  
Deep Learning ◽  
Galaxy Clusters ◽  
Galaxy Cluster ◽  
Dimensional Parameter ◽  
Cluster Galaxies ◽  
Data Intensive ◽  
Luminosity Functions ◽  
Spectroscopic Information ◽  
Photometric Measurements ◽  
Cluster Cores

Context. The next generation of extensive and data-intensive surveys are bound to produce a vast amount of data, which can be efficiently dealt with using machine-learning and deep-learning methods to explore possible correlations within the multi-dimensional parameter space. Aims. We explore the classification capabilities of convolution neural networks (CNNs) to identify galaxy cluster members (CLMs) by using Hubble Space Telescope (HST) images of fifteen galaxy clusters at redshift 0.19 ≲ z ≲ 0.60, observed as part of the CLASH and Hubble Frontier Field programmes. Methods. We used extensive spectroscopic information, based on the CLASH-VLT VIMOS programme combined with MUSE observations, to define the knowledge base. We performed various tests to quantify how well CNNs can identify cluster members on ht basis of imaging information only. Furthermore, we investigated the CNN capability to predict source memberships outside the training coverage, in particular, by identifying CLMs at the faint end of the magnitude distributions. Results. We find that the CNNs achieve a purity-completeness rate ≳90%, demonstrating stable behaviour across the luminosity and colour of cluster galaxies, along with a remarkable generalisation capability with respect to cluster redshifts. We concluded that if extensive spectroscopic information is available as a training base, the proposed approach is a valid alternative to catalogue-based methods because it has the advantage of avoiding photometric measurements, which are particularly challenging and time-consuming in crowded cluster cores. As a byproduct, we identified 372 photometric cluster members, with mag(F814) < 25, to complete the sample of 812 spectroscopic members in four galaxy clusters RX J2248-4431, MACS J0416-2403, MACS J1206-0847 and MACS J1149+2223. Conclusions. When this technique is applied to the data that are expected to become available from forthcoming surveys, it will be an efficient tool for a variety of studies requiring CLM selection, such as galaxy number densities, luminosity functions, and lensing mass reconstruction.

scholarly journals The South Pole Telescope: Unraveling the Mystery of Dark Energy

2016 ◽  
Vol 43 ◽  
pp. 1660189
Author(s):  
Christian L. Reichardt ◽  
Tijmen de Haan ◽  
Lindsey E. Bleem
Keyword(s):  
Dark Energy ◽  
Galaxy Clusters ◽  
Galaxy Cluster ◽  
South Pole ◽  
The South ◽  
Cosmological Constraints ◽  
South Pole Telescope ◽  
Highly Sensitive ◽  
History Of ◽  
The Universe

The South Pole Telescope (SPT) is a 10-meter telescope designed to survey the millimeter-wave sky, taking advantage of the exceptional observing conditions at the Amundsen-Scott South Pole Station. The telescope and its ground-breaking 960-element bolometric camera finished surveying 2500 square degrees at 95. 150, and 220 GHz in November 2011. We have discovered hundreds of galaxy clusters in the SPT-SZ survey through the Sunyaev-Zel’dovich (SZ) effect. The formation of galaxy clusters the largest bound objects in the universe is highly sensitive to dark energy and the history of structure formation. I will discuss the cosmological constraints from the SPT-SZ galaxy cluster sample as well as future prospects with the soon to-be-installed SPT-3G camera.

scholarly journals Ultraviolet signatures of the multiphase intracluster and circumgalactic media in the romulusc simulation

2019 ◽  
Vol 490 (3) ◽  
pp. 4292-4306 ◽  
Author(s):  
Iryna S Butsky ◽  
Joseph N Burchett ◽  
Daisuke Nagai ◽  
Michael Tremmel ◽  
Thomas R Quinn ◽  
...  
Keyword(s):  
Absorption Line ◽  
Galaxy Clusters ◽  
Hubble Space Telescope ◽  
Galaxy Cluster ◽  
Future Prospects ◽  
X Ray ◽  
Cluster Galaxies ◽  
Multiphase Structure ◽  
Wide Range ◽  
Resolution Simulation

ABSTRACT Quasar absorption-line studies in the ultraviolet (UV) can uniquely probe the nature of the multiphase cool–warm (104 &lt; T &lt; 106 K) gas in and around galaxy clusters, promising to provide unprecedented insights into (1) interactions between the circumgalactic medium (CGM) associated with infalling galaxies and the hot (T &gt; 106 K) X-ray emitting intracluster medium (ICM), (2) the stripping of metal-rich gas from the CGM, and (3) a multiphase structure of the ICM with a wide range of temperatures and metallicities. In this work, we present results from a high-resolution simulation of an $\sim 10^{14} \, \mathrm{M}_{\odot }$ galaxy cluster to study the physical properties and observable signatures of this cool–warm gas in galaxy clusters. We show that the ICM becomes increasingly multiphased at large radii, with the cool–warm gas becoming dominant in cluster outskirts. The diffuse cool–warm gas also exhibits a wider range of metallicity than the hot X-ray emitting gas. We make predictions for the covering fractions of key absorption-line tracers, both in the ICM and in the CGM of cluster galaxies, typically observed with the Cosmic Origins Spectrograph aboard the Hubble Space Telescope (HST). We further extract synthetic spectra to demonstrate the feasibility of detecting and characterizing the thermal, kinematic, and chemical composition of the cool–warm gas using H i, O vi, and C iv lines, and we predict an enhanced population of broad Ly α absorbers tracing the warm gas. Lastly, we discuss future prospects of probing the multiphase structure of the ICM beyond HST.

scholarly journals K-CLASH: Strangulation and ram pressure stripping in galaxy cluster members at 0.3 < z < 0.6

2020 ◽  
Vol 496 (3) ◽  
pp. 3841-3861
Author(s):  
Sam P Vaughan ◽  
Alfred L Tiley ◽  
Roger L Davies ◽  
Laura J Prichard ◽  
Scott M Croom ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Clusters ◽  
Galaxy Cluster ◽  
Cluster Galaxies ◽  
Star Forming ◽  
Field Samples ◽  
Ram Pressure ◽  
Field Unit ◽  
Matched Samples ◽  
Average Cluster

ABSTRACT Galaxy clusters have long been theorized to quench the star formation of their members. This study uses integral-field unit observations from the K-band MultiObject Spectrograph (KMOS) – Cluster Lensing And Supernova survey with Hubble (CLASH) survey (K-CLASH) to search for evidence of quenching in massive galaxy clusters at redshifts 0.3 &lt; z &lt; 0.6. We first construct mass-matched samples of exclusively star-forming cluster and field galaxies, then investigate the spatial extent of their H α emission and study their interstellar medium conditions using emission line ratios. The average ratio of H α half-light radius to optical half-light radius ($r_{\mathrm{e}, {\rm {H}\,\alpha }}/r_{\mathrm{e}, R_{\mathrm{c} } }$) for all galaxies is 1.14 ± 0.06, showing that star formation is taking place throughout stellar discs at these redshifts. However, on average, cluster galaxies have a smaller $r_{\mathrm{e}, {\rm {H}\alpha }}/r_{\mathrm{e}, R_{\mathrm{c} } }$ ratio than field galaxies: 〈$r_{\mathrm{e}, {\rm {H}\alpha }}/r_{\mathrm{e}, R_{\mathrm{c} } }$〉 = 0.96 ± 0.09 compared to 1.22 ± 0.08 (smaller at a 98 per cent credibility level). These values are uncorrected for the wavelength difference between H α emission and Rc-band stellar light but implementing such a correction only reinforces our results. We also show that whilst the cluster and field samples follow indistinguishable mass–metallicity (MZ) relations, the residuals around the MZ relation of cluster members correlate with cluster-centric distance; galaxies residing closer to the cluster centre tend to have enhanced metallicities (significant at the 2.6σ level). Finally, in contrast to previous studies, we find no significant differences in electron number density between the cluster and field galaxies. We use simple chemical evolution models to conclude that the effects of disc strangulation and ram-pressure stripping can quantitatively explain our observations.

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