- ID:
- ivo://CDS.VizieR/J/ApJS/247/71
- Title:
- Large-scale environment of radio galaxies. II.
- Short Name:
- J/ApJS/247/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In our previous analysis we investigated the large-scale environment of two samples of radio galaxies (RGs) in the local universe (i.e., with redshifts z_src_<=0.15), classified as FR I and FR II on the basis of their radio morphology. The analysis was carried out using (i) extremely homogeneous catalogs and (ii) a new method, known as cosmological overdensity, to investigate their large-scale environments. We concluded that, independently of the shape of their radio extended structure, RGs inhabit galaxy-rich large-scale environments with similar characteristics and richness. In the present work, we first highlight additional advantages of our procedure, which does not suffer cosmological biases and/or artifacts, and then we carry out an additional statistical test to strengthen our previous results. We also investigate properties of RG environments using those of the cosmological neighbors. We find that large-scale environments of both FR Is and FR IIs are remarkably similar and independent of the properties of central RG. Finally, we highlight the importance of comparing radio sources in the same redshift bins to obtain a complete overview of their large-scale environments.
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- ID:
- ivo://CDS.VizieR/J/AJ/112/1803
- Title:
- Large Scale Structure
- Short Name:
- J/AJ/112/1803
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have extended the CfA Redshift Survey to low galactic latitudes to investigate the relation between the Great Wall in the North Galactic Cap and the Perseus-Pisces chain in the South Galactic Cap. We present redshifts for 2020 galaxies in the Catalogue of Galaxies and of Clusters of Galaxies (Zwicky et al. 1961-68, CGCG, Cat. <VII/4>) in the following regions: 4h<=RA<=8h, 17h<=Dec.<=20h, 0deg<=Dec.<=45deg. In these regions, the redshift catalogue includes 1664 galaxies with B(0)<=15.5 (of which 820 are newly measured) and is 97% complete. We also include redshifts for an additional 356 galaxies in these regions with B(0)>15.5; of these, 148 were previously unmeasured. The CGCG samples the galaxy distribution down to b_(II)_~10deg. In this paper, we discuss the acquisition and reduction of the spectra, and we examine the qualitative features of the redshift distribution. The Great Wall and the Perseus-Pisces chain are not simply connected across the Zone of Avoidance. These structures, which at first appear to be coherent on scales of ~100h^-1^Mpc or more, actually form the boundaries of neighboring voids of considerably smaller scale, approximately 50h^-1^Mpc. The structures delineated by our optically-selected sample are qualitatively similar to those detected by the far-infrared-selected IRAS 1.2 Jansky Survey (Fisher et al., 1995ApJS..100...69F). Although the IRAS survey probes more deeply into the Zone of Avoidance, our optically-selected survey provides better sampling of structures at b_(II)>=10deg. (Copyright) 1996 American Astronomical Society.
- ID:
- ivo://CDS.VizieR/J/MNRAS/327/588
- Title:
- Las Campanas/AAT Rich Cluster Survey - I
- Short Name:
- J/MNRAS/327/588
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Las Campanas Observatory and Anglo-Australian Telescope Rich Cluster Survey (LARCS) is a panoramic imaging and spectroscopic survey of an X-ray luminosity-selected sample of 21 clusters of galaxies at 0.97<z<0.16. Charge-coupled device (CCD) imaging was obtained in B and R of typically 2{deg} wide regions centred on the 21 clusters, and the galaxy sample selected from the imaging is being used for an on-going spectroscopic survey of the clusters with the 2dF spectrograph on the Anglo-Australian Telescope.
- ID:
- ivo://CDS.VizieR/J/ApJS/137/117
- Title:
- Las Campanas Distant Cluster Survey (LCDCS)
- Short Name:
- J/ApJS/137/117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an optically selected catalog of 1073 galaxy cluster and group candidates at 0.3<~z<~1. These candidates are drawn from the Las Campanas Distant Clusters Survey (LCDCS), a drift-scan imaging survey of a 130 square degree strip of the southern sky. The survey data were obtained in 1995 March under photometric conditions using the Las Campanas 1 m telescope, the Great Circle Camera, and the Tek No. 5 CCD. To construct this catalog we utilize a novel detection process in which clusters are detected as positive surface brightness fluctuations in the background sky. This approach permits us to find clusters with significantly shallower data than other matched-filter methods that are based upon number counts of resolved galaxies. Selection criteria for the survey are fully automated so that this sample constitutes a well-defined, homogeneous sample that can be used to address issues of cluster evolution and cosmology. Estimated redshifts are derived for the entire sample, and an observed correlation between surface brightness and velocity dispersion, {sigma}, is used to estimate the limiting velocity dispersion of the survey as a function of redshift.
- ID:
- ivo://CDS.VizieR/J/ApJS/130/237
- Title:
- LCRS loose groups of galaxies
- Short Name:
- J/ApJS/130/237
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A "friends-of-friends" percolation algorithm has been used to extract a catalog of {delta}n/n=80 density enhancements (groups) from the six slices of the Las Campanas Redshift Survey (LCRS). The full catalog contains 1495 groups and includes 35% of the LCRS galaxy sample. A clean sample of 394 groups has been derived by culling groups from the full sample that either are too close to a slice edge, have a crossing time greater than a Hubble time, have a corrected velocity dispersion of zero, or contain a 55"-'orphan' (a galaxy with a mock redshift that was excluded from the original LCRS redshift catalog due to its proximity to another galaxy, i.e., within 55").
- ID:
- ivo://CDS.VizieR/J/MNRAS/406/1318
- Title:
- Lensed-arc statistics of galaxy clusters
- Short Name:
- J/MNRAS/406/1318
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The statistics of strongly lensed arcs in samples of galaxy clusters provide information on cluster structure that is complementary to that from individual clusters. However, samples of clusters that have been analysed to date have been either small, heterogeneous or observed with limited angular resolution. We measure the lensed-arc statistics of 97 clusters imaged at high angular resolution with the Hubble Space Telescope, identifying lensed arcs using two automated arc-detection algorithms. The sample includes similar numbers of X-ray-selected [MAssive Cluster Survey (MACS)] and optically selected [Red-Sequence Cluster Survey (RCS)] clusters, and spans cluster redshifts in the range 0.2<z<1. We compile a catalogue of 42 arcs in the X-ray-selected subsample and seven arcs in the optical subsample. All but five of these arcs are reported here for the first time.
- ID:
- ivo://CDS.VizieR/J/ApJ/792/76
- Title:
- Lensed z~6-8 galaxies behind CLASH clusters
- Short Name:
- J/ApJ/792/76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We utilize 16 band Hubble Space Telescope (HST) observations of 18 lensing clusters obtained as part of the Cluster Lensing And Supernova survey with Hubble (CLASH) Multi-Cycle Treasury program to search for z ~ 6-8 galaxies. We report the discovery of 204, 45, and 13 Lyman-break galaxy candidates at z ~ 6, z ~ 7, and z ~ 8, respectively, identified from purely photometric redshift selections. This large sample, representing nearly an order of magnitude increase in the number of magnified star-forming galaxies at z ~ 6-8 presented to date, is unique in that we have observations in four WFC3/UVIS UV, seven ACS/WFC optical, and all five WFC3/IR broadband filters, which enable very accurate photometric redshift selections. We construct detailed lensing models for 17 of the 18 clusters to estimate object magnifications and to identify two new multiply lensed z >~ 6 candidates. The median magnifications over the 17 clusters are 4, 4, and 5 for the z ~ 6, z ~ 7, and z ~ 8 samples, respectively, over an average area of 4.5 arcmin^2^ per cluster. We compare our observed number counts with expectations based on convolving "blank" field UV luminosity functions through our cluster lens models and find rough agreement down to ~27 mag, where we begin to suffer significant incompleteness. In all three redshift bins, we find a higher number density at brighter observed magnitudes than the field predictions, empirically demonstrating for the first time the enhanced efficiency of lensing clusters over field surveys. Our number counts also are in general agreement with the lensed expectations from the cluster models, especially at z ~ 6, where we have the best statistics.
- ID:
- ivo://CDS.VizieR/J/ApJ/868/129
- Title:
- Lensing analysis in Abell 370
- Short Name:
- J/ApJ/868/129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new gravitational lens model of the Hubble Frontier Fields cluster Abell 370 (z=0.375) using imaging and spectroscopy from Hubble Space Telescope and ground-based spectroscopy. We combine constraints from a catalog of 909 weakly lensed galaxies and 39 multiply imaged sources comprised of 114 multiple images, including a system of multiply imaged candidates at z=7.84+/-0.02, to obtain a best-fit mass distribution using the cluster lens modeling code strong and weak lensing united. As the only analysis of A370 using strong and weak lensing constraints from Hubble Frontier Fields (HFF) data, our method provides an independent check of assumptions on the mass distribution used in other methods. Convergence, shear, and magnification maps are made publicly available through the HFF website (http://www.stsci.edu/hst/campaigns/frontier-fields). We find that the model we produce is similar to models produced by other groups, with some exceptions due to the differences in lensing code methodology. In an effort to study how our total projected mass distribution traces light, we measure the stellar mass density distribution using Spitzer/Infrared array camera imaging. Comparing our total mass density to our stellar mass density in a radius of 0.3Mpc, we find a mean projected stellar to total mass ratio of <f*>=0.011+/-0.003 (stat.) using the diet Salpeter initial mass function. This value is in general agreement with independent measurements of <f*> in clusters of similar total mass and redshift.
- ID:
- ivo://CDS.VizieR/J/ApJ/723/1678
- Title:
- LensPerfect A1689 analysis
- Short Name:
- J/ApJ/723/1678
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a strong lensing (SL) mass model of A1689 which resolves substructures an estimated 25kpc across within the central ~400kpc diameter. We achieve this resolution by perfectly reproducing the observed (strongly lensed) input positions of 168 multiple images of 55 knots residing within 135 images of 42 galaxies. Our model makes no assumptions about light tracing mass, yet we reproduce the brightest visible structures with some slight deviations. A1689 remains one of the strongest known lenses on the sky, with an Einstein radius of R_E_=47.0+/-1.2" (143^+3^_-4_kpc) for a lensed source at z_s_=2. We find that a single Navarro-Frenk-White (NFW) or Sersic profile yields a good fit simultaneously (with only slight tension) to both our SL mass model and published weak lensing (WL) measurements at larger radius (out to the virial radius). Our SL model prefers slightly higher concentrations than previous SL models, bringing our SL+WL constraints in line with other recent derivations. Our results support those of previous studies which find A1689 has either an anomalously large concentration or significant extra mass along the line of sight (perhaps in part due to triaxiality).
- ID:
- ivo://CDS.VizieR/J/A+A/499/47
- Title:
- Lick indices of EDCSN galaxies
- Short Name:
- J/A+A/499/47
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a comprehensive analysis of the stellar population properties (age, metallicity and the alpha-element enhancement [E/Fe]) and morphologies of red-sequence galaxies in 24 clusters and groups from z~0.75 to z~0.45. The dataset, consisting of 215 spectra drawn from the ESO Distant Cluster Survey, constitutes the largest spectroscopic sample at these redshifts for which such an analysis has been conducted. Analysis reveals that the evolution of the stellar population properties of red-sequence galaxies depend on their mass: while the properties of most massive are well described by passive evolution and high-redshift formation, the less massive galaxies require a more extended star formation history. We show that these scenarios reproduce the index-sigma relations as well as the galaxy colours. The two main results of this work are (1) the evolution of the line-strength indices for the red-sequence galaxies can be reproduced if 40% of the galaxies with sigma<175km/s entered the red-sequence between z=0.75 to z=0.45, in agreement with the fraction derived in studies of the luminosity functions, and (2) the percentage of galaxies in the red-sequence with early-type morphologies (E/S0) decreases by 20% from z=0.75 to z=0.45. This can be understood if the red-sequence gets populated at later times with disc galaxies with quenched star formation. We conclude that the processes quenching star formation do not necessarily produce a simultaneous morphological transformation of the galaxies entering the red-sequence.
