The bright galaxy population of five medium redshift clusters

view Abstract Citations (78) References (23) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Rotation Curves for Spiral Galaxies in Clusters. II. Variations as a Function of Cluster Position Whitmore, Bradley C. ; Forbes, Duncan A. ; Rubin, Vera C. Abstract Rotation curves of spiral galaxies in clusters are examined using three criteria: (1) inner and outer velocity gradients; (2) residuals from synthetic rotation curves for field spirals; and (3) M/L gradients. A good correlation is found between the outer gradient of the rotation curve and the galaxy's distance from the center of the cluster, in the sense that the inner galaxies tend to have falling rotation curves, while the outer galaxies, and field galaxies, tend to have flat or rising rotation curves. A similar effect is seen in the residuals between the observed and synthetic rotation curves. A correlation is also found between the M/L gradient across a galaxy and the galaxy's position in the cluster, with the outer galaxies having steeper M/L gradients. An attempt to construct mass models produced inconclusive results. These correlations indicate that the inner cluster environment can strip away some fraction of the mass in the outer halo of a spiral galaxy or, alternatively, may not allow the halo to form. Publication: The Astrophysical Journal Pub Date: October 1988 DOI: 10.1086/166765 Bibcode: 1988ApJ...333..542W Keywords: Galactic Clusters; Galactic Evolution; Galactic Rotation; Galactic Structure; H I Regions; Spiral Galaxies; Correlation; Galactic Mass; Mass To Light Ratios; Morphology; Astrophysics; GALAXIES: CLUSTERING; GALAXIES: EVOLUTION; GALAXIES: INTERNAL MOTIONS; GALAXIES: STRUCTURE full text sources ADS | data products SIMBAD (63) NED (52) Related Materials (1) Part 1: 1988ApJ...333..522R

Recent observations have highlighted a significant population of faint but\nlarge (r_eff>1.5 kpc) galaxies in the Coma cluster. The origin of these Ultra\nDiffuse Galaxies (UDGs) remains puzzling, as the interpretation of the\nobservational results has been hindered by the subjective selection of UDGs,\nand the limited study of only the Coma (and some examples in the Virgo-)\ncluster. We extend the study of UDGs using 8 clusters in the redshift range\n0.044<z<0.063 with deep g- and r-band imaging data taken with MegaCam at the\nCFHT. We describe an automatic selection pipeline for quantitative\nidentification, tested for completeness using image simulations of these\ngalaxies. We find that the abundance of the UDGs we can detect increases with\ncluster mass, reaching ~200 in typical haloes of M200~10^15 Msun. The cluster\nUDGs have colours consistent with the cluster red sequence, and have a steep\nsize distribution that declines as n~r_eff^-3.4. Their radial distribution is\nsignificantly steeper than NFW in the outskirts, and is significantly shallower\nin the inner parts. They follow the same radial distribution as the more\nmassive quiescent galaxies in the clusters, except within the core region of\nr<0.15XR200 (or <300 kpc). Within this region the number density of UDGs drops\nand is consistent with zero. These diffuse galaxies can only resist tidal\nforces down to this cluster-centric distance if they are highly centrally\ndark-matter dominated. The observation that the radial distribution of more\ncompact dwarf galaxies (r_eff<1.0 kpc) with similar luminosities follows the\nsame distribution as the UDGs, but exist down to a smaller distance of 100kpc\nfrom the cluster centres, indicates that they may have similarly massive\nsub-haloes as the UDGs. Although several scenarios can give rise to the UDG\npopulation, our results point to differences in the formation history as the\nmost plausible explanation.\n

Clusters of galaxies represent the largest laboratories in the universe for testing the incredibly chaotic physics governing the collapse of baryons into the stars, galaxies, groups, and diffuse clouds that we see today. Within the cluster environment, there are a wide variety of physical processes that may be acting to transform galaxies. In this thesis, we combine extensive Keck spectroscopy with wide-field HST imaging to perform a detailed case study of two intermediate redshift galaxy clusters, Cl 0024+1654 (z=0.395) and MS 0451-03 (z=0.540). Leveraging a comprehensive multiwavelength data set that spans the X-ray to infrared, and with spectral-line measurements serving as the key to revealing both the recent star-formation histories and kinematics of infalling galaxies, we aim to shed light on the environmental processes that could be acting to transform galaxies in clusters. We adopt a strategy to make maximal use of our HST-based morphologies by splitting our sample of cluster galaxies according to morphological type, characterizing signs of recent evolution in and early types separately. This approach proves to be powerful in identifying galaxies that are currently being altered by an environmental interaction: early-type galaxies that have either been newly transformed or prodded back into an active phase, and spiral galaxies where star formation is being suppressed or enhanced all stand out in our sample. We begin by using variations in the early-type galaxy population as indicators of recent activity. Because ellipticals and S0s form such a homogeneous class in the local universe, we are sensitive to even very subtle signatures of recent and current environmental interactions. This study has yielded two key results: By constructing the Fundamental Plane (FP) of Cl 0024, we observe that elliptical and S0 galaxies exhibit a high scatter in their FP residuals, which occurs only among galaxies in the cluster core, suggesting a turbulent assembly history for Cl 0024 early types. Near the Virial radius of Cl 0024, we observe a number of compact, intermediate-mass ellipticals undergoing a burst of star formation or weak AGN activity, indicated by strong [O II] emission; their locations may mark the minimum radius at which merging is effective in each cluster. While E+S0 galaxies do prove to be sensitive indicators of environmental interaction, it is the spiral galaxies that, of course, host the bulk of star formation within and around these clusters. We therefore probe for kinematic disturbances in spiral disks by measuring resolved rotation curves from optical emission lines, and constructing the Tully-Fisher relation for across Cl 0024 and MS 0451. We find that the cluster Tully-Fisher relation exhibits significantly higher scatter than the field relation. In probing for the origin of this difference, we find that the central mass densities of star-forming exhibit a sharp break near the cluster Virial radius, with in the cluster outskirts exhibiting significantly lower densities. We argue that these results considered together demonstrate that cluster are kinematically disturbed by their environment, likely due to galaxy-galaxy interactions (harassment). We then discuss our most powerful method of tracking galaxy evolution across Cl 0024 and MS 0451: identifying and studying transition galaxies-galaxies whose stellar populations or dynamical states indicate a recent or ongoing change in morphology or star formation rate. Such galaxies are often revealed by star formation histories that seem to be at odds with the galaxy morphologies: for example, spiral galaxies with no signs of star formation, or elliptical galaxies that do show signs of star formation. We identify and study one such class of objects, the spirals in Cl 0024. These objects exhibit no emission lines in their spectra, suggesting a lack of star formation, yet are surprisingly detected in the UV, revealing the presence of young stars. By modeling the different temporal sensitivities of UV and spectroscopic data to recent activity, we show that star formation in Cl 0024 passive has decayed on timescales of less than 1 Gyr, consistent with the action of gas starvation. We then build on and link together our previous indications of galaxy evolution at work, aiming to piece together a more comprehensive picture of how cluster galaxies are affected by their environment at intermediate redshift. To accomplish this, we document what we believe to be the first direct evidence for the transformation of into S0s: through an analysis of their stellar populations and recent star formation rates, we link the passive spiral galaxies in both clusters to their eventual end states as newly generated cluster S0 galaxies. Differences between the two clusters in both the timescales and spatial location of this conversion process allow us to evaluate the relative importance of several proposed physical mechanisms that could be responsible for the transformation. Combined with other diagnostics that are sensitive to either ICM-driven galaxy evolution or galaxy-galaxy interactions, we describe a self-consistent picture of galaxy evolution in clusters. We find that spiral galaxies within infalling groups have already begun a slow process of conversion into S0s primarily via gentle galaxy-galaxy interactions that act to quench star formation. The fates of upon reaching the core of the cluster depend heavily on the cluster ICM, with rapid conversion of all remaining into S0s via ram-pressure stripping in clusters where the ICM is dense. In the presence of a less-dense ICM, the conversion continues at a slower pace, with galaxy-galaxy interactions continuing to play a role along with starvation by the ICM. We conclude that the buildup of the local S0 population through the transformation of spiral galaxies is a heterogeneous process that nevertheless proceeds robustly across a variety of different environments from cluster outskirts to cores.

The influence of the cluster environment on the neutral hydrogen contents of spiral galaxies in clusters has been well established over the past decade. It is found that spirals in the central regions of those clusters having the most intracluster gas and the lowest percentage of spirals exhibit H I deficiencies (when compared with field spirals of the same size and luminosity and morphological type) ranging from a factor of 2 to 10. The Virgo cluster is the best-studied example of the moderately deficient class, and the Coma cluster is the extreme case of the very deficient type. Until recently, however, it has not been possible to study the details of the distribution of the H I in these deficient cluster galaxies. The first detailed studies with synthesis telescopes were carried out (on the Virgo cluster) on the WSRT by Warmels (1986) and on the VLA by van Gorkom et al. (1984). These showed that the H I in the deficient spirals was primarily missing from the outer parts of the galaxies; that is, that the size of the H I disks was much smaller than the optical disks, the opposite of the usual situation in the field. Furthermore, van Gorkom et al. (1984) and Cayette et al. (1988) have several cases of very asymmetric H I distributions, which can reasonably be attributed to either tidal interactions with other cluster members, or to interactions (such as ram-pressure stripping) with the intracluster medium. With these interesting results in hand, I have observed the H I distributions in several deficient spirals in the Coma cluster, where one might expect even stronger effects. Here I give a preliminary account of these observations.

Using data of five clusters of galaxies within the redshift range 0.15 $\leq$ z $\leq$ 0.25, imaged with the Nordic Optical Telescope (NOT) in the central $\approx$ 1 Mpc$^2$ in very good seeing conditions, we have performed an exhaustive inspection of their bright galaxy population. That range of redshift, where only a small amount of data with the required resolution and quality is available, is particularly important for the understanding of the formation and evolution of clusters of galaxies. We have inspected the color-magnitude relation (CMR) for those clusters and measured the blue fraction of galaxies in their cores to check for evidence of evolution as found in other works. Moreover, the visual classification of the galaxy morphology has been performed and the morphology-radius relation has been examined We have not found signs of evolution neither in the slope of the CMR nor in the blue fraction of galaxies. A diversity of situations regarding those parameters and in the morphological mixing has been noticed, with two out of five clusters containing a dominant late-type core population. The cluster A1878 stands out as some of its properties differ from those of the other clusters in the sample. No clear signs of evolution appear in our analysis. The data support the view that the morphology and the stellar content of the galaxies in our clusters have been already settled at z $\sim$ 0.2. Only the fraction of interacting galaxies in the clusters appear to be larger than in clusters like Coma although the number of clusters in the sample is small to give a definitive conclusion.

Clusters of galaxies

We connect galaxy properties with their orbital classification by analysing a sample of galaxies with stellar mass M⋆ ≥ 108.5h−1M⊙ residing in and around massive and isolated galaxy clusters with mass M200 > 1015h−1M⊙ at redshift z = 0. The galaxy population is generated by applying the semi-analytic model of galaxy formation sag on the cosmological simulation MultiDark Planck 2. We classify galaxies considering their real orbits (3D) and their projected phase-space position using the roger code (2D). We define five categories: cluster galaxies, galaxies that have recently fallen into a cluster, backsplash galaxies, infalling galaxies, and interloper galaxies. For each class, we analyse the 0.1(g − r) colour, the specific star formation rate (sSFR), and the stellar age, as a function of the stellar mass. For the 3D classes, we find that cluster galaxies have the lowest sSFR, and are the reddest and the oldest, as expected from environmental effects. Backsplash galaxies have properties intermediate between the cluster and recent infaller galaxies. For each 2D class, we find an important contamination by other classes. We find it necessary to separate the galaxy populations in red and blue to perform a more realistic analysis of the 2D data. For the red population, the 2D results are in good agreement with the 3D predictions. Nevertheless, when the blue population is considered, the 2D analysis only provides reliable results for recent infallers, infalling galaxies and interloper galaxies.

view Abstract Citations (49) References (74) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The evolution of disk galaxies and the S0 problem, revisited. Bothun, G. D. Abstract Relevant properties of galactic clusters in relation to their ability to alter the course of galactic evolution are reviewed, and the extensive data base of Bothun (1982) is used to reexamine the role of the environment in causing the evolution of disk galaxies. Proposed sweeping mechanisms are summarized, including direct collisions, tidal encounters, ram pressure, thermal evaporation, and internal gas removal. Preliminary observational support for stripping, including that from population ratios, hydrogen-deficient spirals in clusters, and optical properties of cluster spirals, is compared with evidence against stripping. Bothun's data are portrayed in the color-gas content plane, and theoretical evolutionary tracks are constructed in that plane to serve as an adjunct to data interpretation. It is concluded that initial conditions of formation and variations in star formation histories have been more important than environmental influences in determining the present-day character of spiral galaxies in clusters. Publication: The Astrophysical Journal Supplement Series Pub Date: September 1982 DOI: 10.1086/190819 Bibcode: 1982ApJS...50...39B Keywords: Disk Galaxies; Galactic Evolution; Spiral Galaxies; Data Bases; Galactic Clusters; Galactic Structure; Hydrogen; Milky Way Galaxy; Star Distribution; Astrophysics full text sources ADS | data products SIMBAD (9)

As galaxies evolve in dense cluster and protocluster environments, they interact and quench their star formation. This gradually transforms the dominant galaxy population from star-forming galaxies to quiescent red galaxies. This transformation is identifiable by observing the galaxy colors and can also be seen in the morphological transformation of late-type galaxies into early-type galaxies, which creates the morphology-density relation observed when populations in clusters are compared to field galaxies at a given epoch. However, high-z (z $>$ 2) galaxy morphology studies are hindered by the high angular resolution necessary to characterize the morphology. We studied HST WFC3 F160W observations of protoclusters from the MAMMOTH survey (BOSS1244 and BOSS1542) at z ∼ 2.23 with populations of previously identified Hα emitters. By measuring the Sérsic index of 151 Hα emitters, we searched for the early morphological transformation of high-z star-forming galaxies in these well-studied large nonvirialized protoclusters, which we think are the precursors of present-day galaxy clusters. The morphology of the populations of star-forming galaxies in protoclusters does not differ from that of their field counterparts. However, we also identified a population of clumpy potentially merging galaxies, which might increase the population of early-type galaxies within these structures. In BOSS1244, which has two previously identified massive quiescent galaxies including a brightest cluster galaxy (BCG), we additionally found an abundance of early-type galaxies near the BCG and two coeval high-z quasars. Although the morphology of field and protocluster galaxies are very similar, the population of early-type star-forming galaxies surrounding the spectroscopically confirmed quiescent BCG in BOSS1244, which is not observed in BOSS1542, might indicate differences in the evolutionary state of these two coeval protoclusters. It might be a sign of an early forming cluster core in BOSS1244.

We present the first measurement of the AGN fraction in high-redshift clusters of galaxies (z~0.6) with spectroscopy of one cluster and archival data for three additional clusters. We identify 8 AGN in all four of these clusters from the Chandra data, which are sensitive to AGN with hard X-ray (2-10keV) luminosity L_{X,H} > 10^43 erg/s in host galaxies more luminous than a rest frame M_R 10^43 erg/s we discovered in our earlier study of eight low-redshift clusters with z=0.06-0.31 (average z~0.2). Three of the four high-redshift cluster datasets are sensitive to nearly L_{X,H} > 10^42 erg/s and we identify seven AGN above this luminosity limit, compared to two in eight, low-redshift clusters. Based on membership estimates for each cluster, we determine that the AGN fraction at z~0.6 is f_A(L_X>10^42;M_R 10^43;M_R<-20) = 0.020 (+0.012/-0.008). These values are approximately a factor of 20 greater than the AGN fractions in lower-redshift (average z~0.2) clusters of galaxies and represent a substantial increase over the factors of 1.5 and 3.3 increase, respectively, in the measured space density evolution of the hard X-ray luminosity function over this redshift range. Potential systematic errors would only increase the significance of our result. The cluster AGN fraction increases more rapidly with redshift than the field and the increase in cluster AGN indicates the presence of an AGN Butcher-Oemler Effect.

This study investigated the properties of the molecular gas content and star formation activity of 17 Virgo spirals, 21 Ursa Major (UMa) spirals, 13 Pisces spiral galaxies, and a comparison sample of 11 field spiral galaxies with a spatially resolved gas and stellar distribution. The H i-deficient galaxies with a defH i &gt; 0.4 have a similar range of CO luminosity normalized by the K-band luminosity (L CO/L K) like the field spirals, although their CO content can be smaller by up to a factor of 2. The CO, H i, and stellar disk diameters are closely related to each other for both cluster and field galaxies, and the relative diameters of the CO and H i disks grow monotonically and smoothly as the H i-to-stellar disk diameter ratio decreases. Cluster galaxies have a molecular gas consumption time up to 10 times shorter than that of the field comparison sample, suggesting a significant change in the molecular gas content and star formation activity among all the cluster galaxies, even when they do not show any sign of H i stripping. The strongly H i-stripped Virgo cluster galaxies show only a modestly reduced total gas consumption time, indicating that the star formation activity and gas consumption are a highly local (rather than global) phenomenon. Our finding is that the depletion of cold gas by ram-pressure stripping and/or starvation caused by preprocessing in each cluster environment makes galaxies evolve passively.

We measured the velocity anisotropy profile, β ( r ), of different galaxy cluster member populations by analysing the stacked projected phase space of nine massive ( M 200c &gt; 7 × 10 14 M ⊙ ) galaxy clusters at intermediate redshifts (0.18 &lt; z &lt; 0.45). We selected our sample of galaxy clusters by choosing the most round and virialised objects among the targets of the CLASH-VLT spectroscopic programme, which offers a large spectral database. Complementary MUSE observations of most of these clusters allowed us to identify an unprecedented number of cluster members, strongly enhancing the precision of our measurement with respect to previous studies. Our sample of cluster members is divided into four classes: the first two are based on colour (red and blue galaxies), and the other two on stellar mass (high and low). To study the velocity anisotropy profile of each cluster-member population, we employed two parallel techniques, namely the MAMPOSSt method (parametric in β ( r )) and the inversion of the Jeans equation (non-parametric in β ( r )). The results from both techniques are found to be in agreement for any given cluster member population, and suggest that the orbital anisotropy in galaxy clusters grows from the centre (where β ≈ 0.2 − 0.4) to the virial radius ( β ≳ 0.8), and it is similar for the different cluster-member populations. We also find an interesting dynamical feature emerging from the Jeans inversion results, that is, a sudden drop in β ( r ) at a distance of ∼250 kpc from the cluster centre. We provide robust anisotropy estimates from our exploration of a highly significant number of model combinations: 72 with MAMPOSSt (varying the mass, surface number density, β ( r ) model, and galaxy population) and 18 (varying total mass model and galaxy population) in the Jeans inversion. Such an extensive investigation of the velocity anisotropy profile in galaxy clusters is a wide basis for future studies of cluster dynamical masses and cluster cosmology in the era of large spectroscopic surveys.

This study presents a novel method for characterizing galaxy clusters by integrating statistical classification techniques with an optimized adaptation of the red sequence approach. The proposed algorithm employs Gaussian mixture models to analyze the distribution of three key variables: r magnitude, g–r color index, and redshift z. To enhance cluster discrimination, we incorporate Mahalanobis distance metrics and modify the conventional red sequence technique by adopting the principal eigenvector as the slope of the cluster. A sample of 114 galaxy groups and clusters within the redshift range 0.002&lt;z&lt;0.45 was used to validate the method. Comparative analyses demonstrate that the proposed approach achieves comparable or, in certain cases, superior performance in cluster characterization relative to the standard red sequence technique. These results highlight the algorithm’s potential as a robust tool for the exploratory identification and initial parameter determination of galaxy clusters, particularly in large-scale surveys. The methodology bridges statistical rigor with established astrophysical techniques, offering a promising avenue for advancing cluster detection in observational cosmology.

The next generation of neutrino and γ-ray detectors should provide new insights into the creation and propagation of high-energy protons within galaxy clusters, probing both the particle physics of cosmic rays interacting with the background medium and t

We compile a sample of X-ray-selected galaxy groups and clusters from the XMM-Newton serendipitous source catalogue (2XMMi-DR3) with optical confirmation and redshift measurement from the Sloan Digital Sky Survey (SDSS). The X-ray cluster candidates were selected from the 2XMMi-DR3 catalogue in the footprint of the SDSS-DR7. We developed a finding algorithm to search for overdensities of galaxies at the positions of the X-ray cluster candidates in the photometric redshift space and to measure the redshifts of the clusters from the SDSS data. The detection algorithm provides the photometric redshift of 530 galaxy clusters. Of these, 310 clusters have a spectroscopic redshift for at least one member galaxy. About 75 percent of the optically confirmed cluster sample are newly discovered X-ray clusters. Moreover, 301 systems are known as optically selected clusters in the literature while the remainder are new discoveries in X-ray and optical bands. The optically confirmed cluster sample spans a wide redshift range 0.03-0.70 (median z=0.32). In this paper, we present the catalogue of X-ray-selected galaxy groups and clusters from the 2XMMi/SDSS galaxy cluster survey. The catalogue has two subsamples: (i) a cluster sample comprising 345 objects with their X-ray spectroscopic temperature and flux from the spectral fitting, and (ii) a cluster sample consisting of 185 systems with their X-ray flux from the 2XMMi-DR3 catalogue, because their X-ray data are insufficient for spectral fitting. The updated L_X-T relation of the current sample with X-ray spectroscopic parameters is presented. We see no evidence for evolution in the slope and intrinsic scatter of the L_X-T relation with redshift when excluding the low-luminosity groups.