Sloan Digital Sky Survey Cluster Research Articles

Probing the Stellar Populations and Star Formation History of Early-type Galaxies at 0 < z < 1.1 in the Rest-frame Ultraviolet

We measure the evolution of the rest-frame near-ultraviolet (NUV)−V colors for early-type galaxies in clusters at 0 < z < 1.1 using data from the Hyper Suprime-Cam Subaru Strategic Program, CFHT Large Area U-band Deep Survey, and local Sloan Digital Sky Survey clusters observed with Galaxy Evolution Explorer. Our results show that there is an excess in the ultraviolet spectrum in most quiescent galaxies (compared to the expectations from models fitting their optical/infrared colors and spectra) below z ∼ 0.6, beyond which the excess UV emission fades rapidly. This evolution of the UV color is only consistent with the presence of a highly evolved, hot horizontal branch subpopulation in these galaxies (among the majority of cool and optically bright stars), comprising on average 10% of the total stellar mass and forming at z > 3. The blue UV colors of early-type galaxies at low–intermediate redshifts are likely driven by this subpopulation being enriched in helium up to ∼44%. At z > 0.8 (when the extra UV component has not yet appeared) the data allow us to constrain the star formation histories of galaxies by fitting models to the evolution of their UV colors: we find that the epoch at which the stellar populations formed lies in the range 3 < z form < 10 (corresponding to 0.5–2.2 Gyr after the Big Bang) with a star formation e-folding timescale of τ = 0.35–0.7 Gyr, suggesting that these galaxies formed the majority of stars at very high redshift, with a brief yet intense burst of star formation activity. The star formation history and chemical evolution of early-type galaxies resemble those of globular clusters, albeit on much larger scales.

The sphere of influence of the bright central galaxies in the diffuse light of SDSS clusters

ABSTRACT The bright central galaxies (BCGs) dominate the inner portion of the diffuse cluster light, but it is still unclear where the intracluster light (ICL) takes over. To investigate the BCG–ICL transition, we stack the images of ∼3000 clusters between 0.2 &amp;lt; $\mathit{ z}$ &amp;lt; 0.3 in the Sloan Digital Sky Survey (SDSS) gri bands, and measure their BCG + ICL stellar surface mass profile $\Sigma _{*}^{\texttt {B+I}}$ down to $3{\times }10^4\,\mathrm{ M}_{\odot }\,\mathrm{kpc}^{-2}$ at $R{\simeq }1\, \mathrm{Mpc}$ (∼32 mag arcsec−2 in the r-band). We develop a physically motivated method to decompose $\Sigma _{*}^{\texttt {B+I}}$ into three components, including an inner de Vaucouleurs’ profile, an outer ICL that follows the dark matter distribution measured from weak lensing, and an intriguing transitional component between 70 and 200 kpc. To investigate the origin of this transition, we split the clusters into two subsamples by their BCG stellar mass $M_*^{\mathrm{BCG}}$ (mass enclosed roughly within 50 kpc) while making sure they have the same distribution of satellite richness. The $\Sigma _{*}^{\texttt {B+I}}$ profiles of the two subsamples differ by more than a factor of 2 at R &amp;lt; 50 kpc, consistent with their 0.34 dex difference in $M_*^{\mathrm{BCG}}$, whereas on scales beyond 400 kpc, the two profiles converge to the same amplitudes, suggesting a satellite-stripping origin of the outer ICL. Remarkably, however, the discrepancy between the two $\Sigma _{*}^{\texttt {B+I}}$ profiles persists at above $50{{\ \rm per\ cent}}$ level on all scales below 200 kpc, thereby revealing the BCG sphere of influence with radius RSOI ≃ 200 kpc. Finally, we speculate that the surprisingly large sphere of influence of the BCG is tied to the elevated escape velocity profile within rs, the characteristic radius of the dark matter haloes.

C3: Cluster Clustering Cosmology. ii. First Detection of the Baryon Acoustic Oscillations Peak in the Three-point Correlation Function of Galaxy Clusters

Abstract Third-order statistics of the cosmic density field provides a powerful cosmological probe containing synergistic information to the more commonly explored second-order statistics. Here, we exploit a spectroscopic catalog of 72,563 clusters of galaxies extracted from the Sloan Digital Sky Survey (SDSS), providing the first detection of the baryon acoustic oscillations (BAO) peak in the three-point correlation function (3PCF) of galaxy clusters. We measure and analyze both the connected and the reduced 3PCF of SDSS clusters from intermediate (r ∼ 10 Mpc h−1) up to large (r ∼ 140 Mpc h−1) scales, exploring a variety of different configurations. From the analysis of reduced 3PCF at intermediate scales, in combination with the analysis of the two-point correlation function, we constrain both the cluster linear and nonlinear bias parameters, b 1 = 2.75 ± 0.03 and b 2 = 1.2 ± 0.5. We analyze the measurements of the 3PCF at larger scales, comparing them with theoretical models. The data show clear evidence of the BAO peak in different configurations, which appears more visible in the reduced 3PCF rather than in the connected one. From the comparison between theoretical models that do or do not consider the BAO peak, we obtain a quantitative estimate of this evidence, with a Δχ 2 between 2 and 94, depending on the considered configuration. Finally, we set up a generic framework to estimate the expected signal-to-noise ratio of the BAO peak in the 3PCF, exploring different possible definitions that can be used to forecast the most favorable configurations to be explored in future surveys, and applying it to the case of the Euclid mission.

Constraints on the Mass–Richness Relation from the Abundance and Weak Lensing of SDSS Clusters

Abstract We constrain the scaling relation between optical richness (λ) and halo mass (M) for a sample of Sloan Digital Sky Survey (SDSS) red-sequence Matched-filter Probabilistic Percolation (redMaPPer) galaxy clusters within the context of the Planck cosmological model. We use a forward modeling approach where we model the probability distribution of optical richness for a given mass, . To model the abundance and the stacked lensing profiles, we use an emulator specifically built to interpolate the halo mass function and the stacked lensing profile for an arbitrary set of halo mass and redshift, which is calibrated based on a suite of high-resolution N-body simulations. We apply our method to 8312 SDSS redMaPPer clusters with 20 ≤ λ ≤ 100 and 0.10 ≤ z λ ≤ 0.33 and show that the lognormal distribution model for , with four free parameters, well reproduces the measured abundances and lensing profiles simultaneously. The constraints are characterized by the mean relation, , with and (68% CL), where the pivot mass scale M pivot = 3 × 1014 h −1 M ⊙, and the scatter with and . We find that a large scatter in halo masses is required at the lowest-richness bins (20 ≤ λ ≲ 30) in order to reproduce the measurements. Without such a large scatter, the model prediction for the lensing profiles tends to overestimate the measured amplitudes. This might imply a possible contamination of intrinsically low-richness clusters due to the projection effects. Such a low-mass halo contribution is significantly reduced when applying our method to the sample of 30 ≤ λ ≤ 100.

A cluster finding algorithm based on the multiband identification of red sequence galaxies

We present a new algorithm, CAMIRA, to identify clusters of galaxies in wide-field imaging survey data. We base our algorithm on the stellar population synthesis model to predict colours of red-sequence galaxies at a given redshift for an arbitrary set of bandpass filters, with additional calibration using a sample of spectroscopic galaxies to improve the accuracy of the model prediction. We run the algorithm on ~11960 deg^2 of imaging data from the Sloan Digital Sky Survey (SDSS) Data Release 8 to construct a catalogue of 71743 clusters in the redshift range 0.1<z<0.6 with richness after correcting for the incompleteness of the richness estimate greater than 20. We cross-match the cluster catalogue with external cluster catalogues to find that our photometric cluster redshift estimates are accurate with low bias and scatter, and that the corrected richness correlates well with X-ray luminosities and temperatures. We use the publicly available Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS) shear catalogue to calibrate the mass-richness relation from stacked weak lensing analysis. Stacked weak lensing signals are detected significantly for 8 subsamples of the SDSS clusters divided by redshift and richness bins, which are then compared with model predictions including miscentring effects to constrain mean halo masses of individual bins. We find the richness correlates well with the halo mass, such that the corrected richness limit of 20 corresponds to the cluster virial mass limit of about 1 \times 10^14 M_Sun/h for the SDSS DR8 cluster sample.

THE REST-FRAME OPTICAL LUMINOSITY FUNCTION OF CLUSTER GALAXIES ATz&lt; 0.8 AND THE ASSEMBLY OF THE CLUSTER RED SEQUENCE

We present the rest-frame optical luminosity function (LF) of red sequence galaxies in 16 clusters at 0.4<z<0.8 drawn from the ESO Distant Cluster Survey (EDisCS). We compare our clusters to an analogous sample from the Sloan Digital Sky Survey (SDSS) and match the EDisCS clusters to their most likely descendants. We measure all LFs down to M M* + (2.5 - 3.5). At z<0.8, the bright end of the LF is consistent with passive evolution but there is a significant build-up of the faint end of the red sequence towards lower redshift. There is a weak dependence of the LF on cluster velocity dispersion for EDisCS but no such dependence for the SDSS clusters. We find tentative evidence that red sequence galaxies brighter than a threshold magnitude are already in place, and that this threshold evolves to fainter magnitudes toward lower redshifts. We compare the EDisCS LFs with the LF of co-eval red sequence galaxies in the field and find that the bright end of the LFs agree. However, relative to the number of bright red galaxies, the field has more faint red galaxies than clusters at 0.6<z<0.8 but fewer at 0.4<z<0.6, implying differential evolution. We compare the total light in the EDisCS cluster red sequences to the total red sequence light in our SDSS cluster sample. Clusters at 0.4<z<0.8 must increase their luminosity on the red sequence (and therefore stellar mass in red galaxies) by a factor of 1-3 by z=0. The necessary processes that add mass to the red sequence in clusters predict local clusters that are over-luminous as compared to those observed in the SDSS. The predicted cluster luminosities can be reconciled with observed local cluster luminosities by combining multiple previously known effects.

Mass and Redshift Dependence of Star Formation in Relaxed Galaxy Clusters

We investigate the star formation properties of dynamically relaxed galaxy clusters as a function of cluster mass for 308 low-redshift clusters drawn from the Sloan Digital Sky Survey (SDSS) C4 cluster catalog. It is important to establish if cluster star formation properties have a mass dependence before comparing clusters at different epochs, and here we use cluster velocity dispersion, σ, as a measure of cluster mass. We select clusters with no significant substructure, a subset of the full C4 sample, so that velocity dispersion is an accurate tracer of cluster mass. We find that the total stellar mass, the number of star-forming galaxies, and total star formation rate scale linearly with the number of member galaxies, with no residual dependence on cluster velocity dispersion. With the mass-dependence of cluster star formation rates established, we compare the SDSS clusters with a sample of z 0.75 clusters from the literature and find that on average (correcting for the mass growth of clusters between the two redshifts) the total Hα luminosity of the high-redshift clusters is 10 times greater than that of the low-redshift clusters. This can be explained by a decline in the Hα luminosities of individual cluster galaxies by a factor of up to ~10 since z 0.75. The magnitude of this evolution is comparable to that of field galaxies over a similar redshift interval, and thus the effect of the cluster environment on the evolution of star-forming galaxies is at most modest. Our results suggest that the physical mechanism driving the evolution of cluster star formation rates is independent of cluster mass, at least for clusters with velocity dispersion greater than 450 km s−1, and operates over a fairly long timescale such that the star formation rates of individual galaxies decline by an order of magnitude over ~7 billion years.

The Dust Content of Galaxy Clusters

We report on the detection of reddening toward z ∼ 0.2 galaxy clusters. This is measured by correlating the Sloan Digital Sky Survey cluster and quasar catalogs and by comparing the photometric and spectroscopic properties of quasars behind the clusters to those in the field. We find mean E(B − V) values of a few × 10−3 mag for sight lines passing ~Mpc from the clusters' centers. The reddening curve is typical of dust but cannot be used to distinguish between different dust types. The radial dependence of the extinction is shallow near the cluster center suggesting that most of the detected dust lies at the outskirts of the clusters. Gravitational magnification of background z ∼ 1.7 sources seen on Mpc (projected) scales around the clusters is found to be of order a few percent, in qualitative agreement with theoretical predictions. Contamination by different spectral properties of the lensed quasar population is unlikely but cannot be excluded.

Weak Lensing of Galaxy Clusters in Modified Newtonian Dynamics

We study weak gravitational lensing of galaxy clusters in terms of the MOND (MOdified Newtonian Dynamics) theory. We calculate shears and convergences of background galaxies for three clusters (A1689, CL0024+1654, CL1358+6245) and the mean profile of 42 SDSS (Sloan Digital Sky Survey) clusters and compare them with observational data. The mass profile is modeled as a sum of X-ray gas, galaxies and dark halo. For the shear as a function of the angular radius, MOND predicts a shallower slope than the data irrespective of the critical acceleration parameter $g_0$. The dark halo is necessary to explain the data for any $g_0$ and for three interpolation functions. If the dark halo is composed of massive neutrinos, its mass should be heavier than 2 eV. However the constraint still depends on the dark halo model and there are systematic uncertainties, and hence the more careful study is necessary to put a stringent constraint.

The Evolution of the Star Formation Activity in Galaxies and Its Dependence on Environment

We study how the proportion of star-forming galaxies evolves between z ¼ 0:8 and 0 as a function of galaxy environment,usingtheOiilineinemissionasasignatureofongoingstarformation.Our high-zdatasetcomprises16 clusters, 10 groups, and another 250 galaxies in poorer groups and the field at z ¼ 0:4 0:8 from the ESO Distant Cluster Survey, plus another 9 massive clusters at similar redshifts. As a local comparison, we use galaxy systems selected from the Sloan Digital Sky Survey (SDSS) at 0:04 < z < 0:08. At high z most systems follow a broad anticorrelation between the fraction of star-forming galaxies and the system velocity dispersion. At face value, this suggests that at z ¼ 0:4 0:8 the mass of the system largely determines the proportion of galaxies with ongoing star formation. At these redshifts the strength of star formation (as measured by the O ii equivalent width) in star-forming galaxies is also found to vary systematically with environment. SDSS clusters have much lower fractions of starforming galaxies than clusters at z ¼ 0:4 0:8 and, in contrast with the distant clusters, show a plateau for velocity dispersions � 550kms � 1 ,where thefraction ofgalaxieswithOiiemission doesnotvarysystematicallywithvelocity dispersion. We quantify the evolution of the proportion of star-forming galaxies as a function of the system velocity dispersion and find that it is strongest in intermediate-mass systems (� � 500 600 km s � 1 at z ¼ 0). To understandtheoriginoftheobservedtrends,weusethePress-Schechter formalismandtheMillenniumSimulationandshow thatgalaxystarformationhistoriesmaybecloselyrelatedtothegrowthhistoryofclustersandgroups.Ifthescenariowe propose is roughly correct, the link between galaxy properties and environment is extremely simple to predict purely from a knowledge of the growth of dark matter structures. Subject headings: cosmology: observations — galaxies: clusters: general — galaxies: evolution — galaxies: fundamental parameters — galaxies: stellar content

Modelling the two-point correlation function of galaxy clusters in the Sloan Digital Sky Survey

We study the clustering properties of the recently compiled Sloan Digital Sky Survey (SDSS) cluster catalogue using the two-point correlation function in redshift space. We divide the total SDSS sample into two richness subsamples, roughly corresponding to Abell R≥ 0 and Automated Plate Measuring (APM) clusters, respectively. If the two-point correlations are modelled as a power law, ξ(r) = (r0/r)γ, then the best-fitting parameters for the two subsamples are r0= 20.7+4.0−3.8h−1 Mpc with γ= 1.6+0.4−0.4 and r0= 9.7+1.2−1.2 with γ= 2.0+0.7−0.5h−1 Mpc, respectively. Our results are consistent with the dependence of cluster richness on the cluster correlation length. Finally, comparing the SDSS cluster correlation function with predictions from three flat cosmological models (Ωm= 0.3) with dark energy (quintessence), we estimate the cluster redshift-space distortion parameter β≃Ω0.6m/b0 and the cluster bias at the present time. For the Λ cold dark matter case we find β= 0.2+0.029−0.016, which is in agreement with the results based on large-scale cluster motions.

Cosmological Constraints from a Combined Analysis of the Cluster Mass Function and Microwave Background Anisotropies

We present constraints on several cosmological parameters from a combined analysis of the most recent cosmic microwave background anisotropy data and the Sloan Digital Sky Survey cluster mass function. We find that the combination of the two data sets breaks several degeneracies among the parameters and provides the following constraints: σ8 = 0.76 ± 0.09, Ωm = 0.26, h = 0.66, n = 0.96 ± 0.05, and τc = 0.07.