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- ID:
- ivo://CDS.VizieR/J/ApJ/686/966
- Title:
- Spitzer-FLS catalog of clusters of galaxies
- Short Name:
- J/ApJ/686/966
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 99 candidate clusters and groups of galaxies in the redshift range 0.1<z_phot_<1.3 discovered in the Spitzer First-Look Survey (FLS). The clusters are selected by their Rc-3.6um galaxy color-magnitude relation using the cluster red-sequence algorithm. Using this cluster sample, we compute the 3.6, 4.5, 5.8, and 8.0um, cluster luminosity functions (LFs).
- ID:
- ivo://CDS.VizieR/J/ApJ/837/88
- Title:
- SPT-GMOS spectroscopy of gal. in massive clusters
- Short Name:
- J/ApJ/837/88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The velocity distribution of galaxies in clusters is not universal; rather, galaxies are segregated according to their spectral type and relative luminosity. We examine the velocity distributions of different populations of galaxies within 89 Sunyaev Zel'dovich (SZ) selected galaxy clusters spanning 0.28<z<1.08. Our sample is primarily draw from the SPT-GMOS spectroscopic survey, supplemented by additional published spectroscopy, resulting in a final spectroscopic sample of 4148 galaxy spectra -- 2868 cluster members. The velocity dispersion of star-forming cluster galaxies is 17+/-4% greater than that of passive cluster galaxies, and the velocity dispersion of bright (m<m^*^-0.5) cluster galaxies is 11+/-4% lower than the velocity dispersion of our total member population. We find good agreement with simulations regarding the shape of the relationship between the measured velocity dispersion and the fraction of passive versus star-forming galaxies used to measure it, but we find a small offset between this relationship as measured in data and simulations, which suggests that our dispersions are systematically low by as much as 3% relative to simulations. We argue that this offset could be interpreted as a measurement of the effective velocity bias that describes the ratio of our observed velocity dispersions and the intrinsic velocity dispersion of dark matter particles in a published simulation result. Measuring velocity bias in this way suggests that large spectroscopic surveys can improve dispersion-based mass-observable scaling relations for cosmology even in the face of velocity biases, by quantifying and ultimately calibrating them out.
- ID:
- ivo://CDS.VizieR/J/MNRAS/474/1065
- Title:
- SPT-selected galaxy clusters X-ray analysis
- Short Name:
- J/MNRAS/474/1065
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse Chandra X-ray Observatory observations of a set of galaxy clusters selected by the South Pole Telescope using a new publicly available forward-modelling projection code, MBPROJ2, assuming hydrostatic equilibrium. By fitting a power law plus constant entropy model we find no evidence for a central entropy floor in the lowest entropy systems. A model of the underlying central entropy distribution shows a narrow peak close to zero entropy which accounts for 60 per cent of the systems, and a second broader peak around 130keV.cm^2^. We look for evolution over the 0.2-1.2 redshift range of the sample in density, pressure, entropy and cooling time at 0.015R_500_ and at 10kpc radius. By modelling the evolution of the central quantities with a simple model, we find no evidence for a non-zero slope with redshift. In addition, a non-parametric sliding median shows no significant change. The fraction of cool-core clusters with central cooling times below 2Gyr is consistent above and below z=0.6 (~30-40 per cent). Both by comparing the median thermodynamic profiles, centrally biased towards cool cores, in two redshift bins, and by modelling the evolution of the unbiased average profile as a function of redshift, we find no significant evolution beyond self-similar scaling in any of our examined quantities. Our average modelled radial density, entropy and cooling-time profiles appear as power laws with breaks around 0.2R_500_. The dispersion in these quantities rises inwards of this radius to around 0.4dex, although some of this scatter can be fitted by a bimodal model.
- ID:
- ivo://CDS.VizieR/J/ApJ/878/55
- Title:
- SPT-SZ clusters with optical & X-ray data
- Short Name:
- J/ApJ/878/55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derive cosmological constraints using a galaxy cluster sample selected from the 2500deg^2^ SPT-SZ survey. The sample spans the redshift range 0.25<z<1.75 and contains 343 clusters with SZ detection significance {xi}>5. The sample is supplemented with optical weak gravitational lensing measurements of 32 clusters with 0.29<z<1.13 (from Magellan and Hubble Space Telescope) and X-ray measurements of 89 clusters with 0.25<z<1.75 (from Chandra). We rely on minimal modeling assumptions: (i) weak lensing provides an accurate means of measuring halo masses, (ii) the mean SZ and X-ray observables are related to the true halo mass through power-law relations in mass and dimensionless Hubble parameter E(z) with a priori unknown parameters, and (iii) there is (correlated, lognormal) intrinsic scatter and measurement noise relating these observables to their mean relations. We simultaneously fit for these astrophysical modeling parameters and for cosmology. Assuming a flat {nu}{Lambda}CDM model, in which the sum of neutrino masses is a free parameter, we measure {Omega}_m_=0.276+/-0.047, {sigma}_8_=0.781+/-0.037, and {sigma}_8_({Omega}_m_/0.3)^0.2^=0.766+/-0.025. The redshift evolutions of the X-ray Y_X_-mass and M_gas_-mass relations are both consistent with self-similar evolution to within 1{sigma}. The mass slope of the Y_X_-mass relation shows a 2.3{sigma} deviation from self-similarity. Similarly, the mass slope of the M_gas_-mass relation is steeper than self-similarity at the 2.5{sigma} level. In a {nu}wCDM cosmology, we measure the dark energy equation-of-state parameter w=-1.55+/-0.41 from the cluster data. We perform a measurement of the growth of structure since redshift z~1.7 and find no evidence for tension with the prediction from general relativity. This is the first analysis of the SPT cluster sample that uses direct weak-lensing mass calibration and is a step toward using the much larger weak-lensing data set from DES. We provide updated redshift and mass estimates for the SPT sample.
- ID:
- ivo://CDS.VizieR/J/ApJ/792/45
- Title:
- SPT-SZ survey galaxy clusters optical spectroscopy
- Short Name:
- J/ApJ/792/45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical spectroscopy of galaxies in clusters detected through the Sunyaev-Zel'dovich (SZ) effect with the South Pole Telescope (SPT). We report our own measurements of 61 spectroscopic cluster redshifts, and 48 velocity dispersions each calculated with more than 15 member galaxies. This catalog also includes 19 dispersions of SPT-observed clusters previously reported in the literature. The majority of the clusters in this paper are SPT-discovered; of these, most have been previously reported in other SPT cluster catalogs, and five are reported here as SPT discoveries for the first time. By performing a resampling analysis of galaxy velocities, we find that unbiased velocity dispersions can be obtained from a relatively small number of member galaxies (<~ 30), but with increased systematic scatter. We use this analysis to determine statistical confidence intervals that include the effect of membership selection. We fit scaling relations between the observed cluster velocity dispersions and mass estimates from SZ and X-ray observables. In both cases, the results are consistent with the scaling relation between velocity dispersion and mass expected from dark-matter simulations. We measure a ~30% log-normal scatter in dispersion at fixed mass, and a ~10% offset in the normalization of the dispersion-mass relation when compared to the expectation from simulations, which is within the expected level of systematic uncertainty.
- ID:
- ivo://CDS.VizieR/J/ApJ/594/154
- Title:
- 160 square degree ROSAT survey
- Short Name:
- J/ApJ/594/154
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the revised catalog of galaxy clusters detected as extended X-ray sources in the 160 Square Degree ROSAT Survey, including spectroscopic redshifts and X-ray luminosities for 200 of the 201 members. The median redshift is z_median_=0.25, and the median X-ray luminosity is L_X,median_=4.2x10^43^h_50_^2^erg/s (0.5-2.0keV). This is the largest high-redshift sample of X-ray-selected clusters published to date. There are 73 objects at z>0.3 and 22 objects at z>0.5 drawn from a statistically complete flux-limited survey with a median object flux of 1.4x10^-13^erg/cm^2^/s. We describe the optical follow-up of these clusters with an emphasis on our spectroscopy, which has yielded 155 cluster redshifts, 110 of which are presented here for the first time. These measurements, combined with 45 from the literature and other sources, provide near-complete spectroscopic coverage for our survey. We discuss the final optical identifications for the extended X-ray sources in the survey region and compare our results to similar X-ray cluster searches.
- ID:
- ivo://CDS.VizieR/J/A+A/312/745
- Title:
- SSRS groups of galaxies redshift neighbourhood
- Short Name:
- J/A+A/312/745
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Southern Sky Redshift Survey (SSRS) includes 13 groups of 5 or more members with velocities >=2000km/s. By measuring redshifts and accumulating data from the literature, we increase the total number of known group members from 89 to 218. We also measured new redshifts for 59 foreground/background galaxies superimposed on the group neighborhoods. The velocity dispersions of the groups are remarkably stable.
- ID:
- ivo://CDS.VizieR/J/A+A/647/A135
- Title:
- 35 star clusters and fields in the SMC
- Short Name:
- J/A+A/647/A135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this work we study 35 stellar clusters in the Small Magellanic Cloud (SMC) in order to provide their mean metallicities and ages. We also provide mean metallicities of the fields surrounding the clusters. We used Stroemgren photometry obtained with the 4.1 m SOAR telescope and take advantage of (b-y) and m1 colors for which there is a metallicity calibration presented in the literature. The spatial metallicity and age distributions of clusters across the SMC are investigated using the results obtained by Stroemgren photometry. We confirm earlier observations that younger, more metal-rich star clusters are concentrated in the central regions of the galaxy, while older, more metal-poor clusters are located farther from the SMC center. We construct the age-metallicity relation for the studied clusters and find good agreement with theoretical models of chemical enrichment, and with other literature age and metallicity values for those clusters. We also provide the mean metallicities for old and young populations of the field stars surrounding the clusters, and find the latter to be in good agreement with recent studies of the SMC Cepheid population. Finally, the Stroemgren photometry obtained for this study is made publicly available.
- ID:
- ivo://CDS.VizieR/J/MNRAS/453/1965
- Title:
- Star-forming compact groups
- Short Name:
- J/MNRAS/453/1965
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a local sample (z<0.15) of 280 star-forming compact groups (SFCGs) of galaxies identified in the ultraviolet Galaxy Evolution EXplorer (GALEX) All-sky Imaging Survey (AIS). So far, just one prototypical example of SFCG, the Blue Infalling Group, has been studied in detail in the Local Universe. The sample of SFCGs is mainly the result of applying a Friends-of-Friends group finder in the space of celestial coordinates with a maximum linking-length of 1.5 arcmin and choosing groups with a minimum number of four members of bright UV-emitting 17<FUV<20.5 sources (mostly galaxies) from the GALEX/AIS catalogue. The result from the search are 280 galaxy groups composed by 226, 39, 11 and 4 groups of four, five, six and seven bright ultraviolet (UV) members, respectively. Only 59 of these 280 newly identified SFCGs have a previous catalogued group counterpart. Group redshifts are available for at least one member in 75 per cent of the SFCGs, and over 40 per cent of the SFCGs have redshifts measured for two or more galaxies. 26 of the SFCGs appear to be located in the infalling regions of clusters with known redshift. The SFCG sample presents a combination of properties different from the group samples studied up to now, such as low-velocity dispersions (sigma_l-o-s_~120km/s), small crossing-times (H_0_t_c_~0.05) and high star formation content (95 per cent of star-forming galaxies). This points to the SFCGs being in an evolutionary stage distinct from those groups selected in the optical and near-infrared ranges. Once redshifts are obtained to discard interlopers, SFCGs will constitute a unique sample of SFCGs.
