- ID:
- ivo://CDS.VizieR/J/ApJS/191/254
- Title:
- GMBCG galaxy cluster catalog from SDSS DR7
- Short Name:
- J/ApJS/191/254
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a large catalog of optically selected galaxy clusters from the application of a new Gaussian Mixture Brightest Cluster Galaxy (GMBCG) algorithm to SDSS Data Release 7 data. The algorithm detects clusters by identifying the red-sequence plus brightest cluster galaxy (BCG) feature, which is unique for galaxy clusters and does not exist among field galaxies. Red-sequence clustering in color space is detected using an Error Corrected Gaussian Mixture Model. We run GMBCG on 8240 deg^2^ of photometric data from SDSS DR7 to assemble the largest ever optical galaxy cluster catalog, consisting of over 55,000 rich clusters across the redshift range from 0.1<z<0.55. We present Monte Carlo tests of completeness and purity and perform cross-matching with X-ray clusters and with the maxBCG sample at low redshift. These tests indicate high completeness and purity across the full redshift range for clusters with 15 or more members.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/VII/42A
- Title:
- GMP catalogue: galaxies in the Coma cluster
- Short Name:
- VII/42A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalogue contains isophotal magnitudes, radii, intensity profiles, ellipticities and (b-r) colours for 6724 galaxies with b26.5 < 21.0 mag in a 26.3 degree square area centered on the Coma cluster. The sample is essentially complete to b26.5 = 20.0, with rms deviations in b26.5, r24.75 and (b-r) all about 0.15mag. The plates used in this investigation were all taken with the Palomar 48-inch Schmidt telescope during good conditions in 1976 May.
- ID:
- ivo://CDS.VizieR/J/MNRAS/372/1425
- Title:
- Gravitational lensing analysis of Abell 1689
- Short Name:
- J/MNRAS/372/1425
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have derived the mass distribution of galaxy cluster Abell 1689 within 0.3h^-1^_70_Mpc of the cluster centre using its strong lensing (SL) effect on 32 background galaxies, which are mapped in altogether 107 multiple images. The multiple images are based on some from the literature with modifications to both include new and exclude some of the original image systems. The cluster profile is explored further out to ~2.5h^-1^_70_Mpc with weak lensing (WL) shear measurements from the literature. The masses of ~200 cluster galaxies are measured with the Fundamental Plane (FP) in order to model accurately the small-scale mass structure in the cluster. The cluster galaxies are modelled as elliptical truncated isothermal spheres. The scalings of the truncation radii with the velocity dispersions of galaxies are assumed to match those of: (i) field galaxies; and (ii) theoretical expectations for galaxies in dense environments. The dark matter (DM) component of the cluster is described by either non-singular isothermal ellipsoids (NSIE) or elliptical versions of the universal DM profile (elliptical Navarro, Frenk & White, ENFW). To account for substructure in the DM we allow for two DM haloes.
- ID:
- ivo://CDS.VizieR/J/ApJ/736/43
- Title:
- Gravitational lensing flexion in A1689 with an AIM
- Short Name:
- J/ApJ/736/43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Measuring dark matter substructure within galaxy cluster halos is a fundamental probe of the {Lambda}CDM model of structure formation. Gravitational lensing is a technique for measuring the total mass distribution which is independent of the nature of the gravitating matter, making it a vital tool for studying these dark-matter-dominated objects. We present a new method for measuring weak gravitational lensing flexion fields, the gradients of the lensing shear field, to measure mass distributions on small angular scales. While previously published methods for measuring flexion focus on measuring derived properties of the lensed images, such as shapelet coefficients or surface brightness moments, our method instead fits a mass-sheet transformation invariant Analytic Image Model (AIM) to each galaxy image. This simple parametric model traces the distortion of lensed image isophotes and constrains the flexion fields. We test the AIM method using simulated data images with realistic noise and a variety of unlensed image properties, and show that it successfully reproduces the input flexion fields. We also apply the AIM method for flexion measurement to Hubble Space Telescope observations of A1689 and detect mass structure in the cluster using flexion measured with this method. We also estimate the scatter in the measured flexion fields due to the unlensed shape of the background galaxies and find values consistent with previous estimates.
- ID:
- ivo://CDS.VizieR/J/ApJ/627/32
- Title:
- Gravitationally lensed arcs in the HST WFPC2 archive
- Short Name:
- J/ApJ/627/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a systematic search for gravitationally lensed arcs in clusters of galaxies located in the Hubble Space Telescope Wide Field and Planetary Camera 2 data archive. By carefully examining the images of 128 clusters we have located 12 candidate radial arcs and 104 tangential arcs, each of whose length-to-width ratio exceeds 7. In addition, 24 other radial arc candidates were identified with a length-to-width ratio of less than 7. Keck spectroscopy of 17 candidate radial arcs suggests that contamination of the radial arc sample from nonlensed objects is ~30%-50%.
- ID:
- ivo://CDS.VizieR/J/A+A/352/39
- Title:
- Great Attractor region redshifts
- Short Name:
- J/A+A/352/39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the third of a series of papers on large-scale structures behind the southern Milky Way, we report here on redshifts obtained at the South African Astronomical Observatory (SAAO) in the Great Attractor region (318{deg}<~l<~340{deg}, |b|<=10{deg}, Woudt, 1998, Ph. D. Thesis, University of Cape Town). This region encompasses the peak in the reconstructed mass density field, associated with the Great Attractor (Kolatt et al., 1995MNRAS.275..797K, Dekel et al., 1999ApJ...522....1D) and covers the crossing of the Supergalactic Plane with the Galactic Plane. Our deep optical galaxy search in the Zone of Avoidance (ZOA) in this region (Woudt, 1998, Ph. D. Thesis, University of Cape Town) has resulted in the detection of 4423 galaxies with observed diameters larger than 0.2arcmin. We have obtained reliable redshifts for 309 galaxies of the 4423 galaxies with the ``Unit'' spectrograph (first with a Reticon, then with a CCD detector) at the 1.9-m telescope of the SAAO. An additional 13 tentative redshifts are presented.
- ID:
- ivo://CDS.VizieR/J/A+A/536/A89
- Title:
- g'r'i' and redshift of Abell 2254 galaxies
- Short Name:
- J/A+A/536/A89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The mechanisms giving rise to diffuse radio emission in galaxy clusters and, in particular, their connection with cluster mergers are still being debated. We explore the internal dynamics of Abell 2254, which has been shown to host a very clumpy and irregular radio halo. Our analysis is mainly based on redshift data for 128 galaxies acquired at the Telescopio Nazionale Galileo. We combined galaxy velocities and positions to select 110 cluster galaxies and analyze its internal dynamics. We also used new (g', r', i') photometric data acquired at the Isaac Newton Telescope, and (V, i') photometric data available in the Subaru Archive. X-ray data from the XMM-Newton Science Archive were analyzed to study the hot gas component.
- ID:
- ivo://CDS.VizieR/J/AJ/119/1562
- Title:
- gri photometry of 48 galaxy clusters
- Short Name:
- J/AJ/119/1562
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present gri CCD photometry of 44 Abell clusters and four cluster candidates. Twenty-one clusters in our sample have spectroscopic redshifts. Fitting a relation between mean g, r, and i magnitudes and redshift for this subsample, we have calculated photometric redshifts for the remainder with an estimated accuracy of approximately 0.03. The resulting redshift range for the sample is 0.03 < z < 0.38. Color-magnitude diagrams are presented for the complete sample and used to study evolution of the galaxy population in the cluster environment.
- ID:
- ivo://CDS.VizieR/J/ApJ/812/114
- Title:
- Grism Lens-Amplified Survey from Space (GLASS). I.
- Short Name:
- J/ApJ/812/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We give an overview of the Grism Lens Amplified Survey from Space (GLASS), a large Hubble Space Telescope program aimed at obtaining grism spectroscopy of the fields of 10 massive clusters of galaxies at redshift z=0.308-0.686, including the Hubble Frontier Fields (HFF). The Wide Field Camera 3 (WFC3) yields near-infrared spectra of the cluster cores covering the wavelength range 0.81-1.69{mu}m through grisms G102 and G141, while the Advanced Camera for Surveys in parallel mode provides G800L spectra of the infall regions of the clusters. The WFC3 spectra are taken at two almost orthogonal position angles in order to minimize the effects of confusion. After summarizing the scientific drivers of GLASS, we describe the sample selection as well as the observing strategy and data processing pipeline. We then utilize MACS J0717.5+3745, a HFF cluster and the first one observed by GLASS, to illustrate the data quality and the high-level data products. Each spectrum brighter than H_AB_=23 is visually inspected by at least two co-authors and a redshift is measured when sufficient information is present in the spectra. Furthermore, we conducted a thorough search for emission lines through all of the GLASS WFC3 spectra with the aim of measuring redshifts for sources with continuum fainter than H_AB_=23. We provide a catalog of 139 emission-line-based spectroscopic redshifts for extragalactic sources, including three new redshifts of multiple image systems (one probable, two tentative).
- ID:
- ivo://CDS.VizieR/J/A+A/596/A14
- Title:
- Group catalogues of the local universe
- Short Name:
- J/A+A/596/A14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Friends-of-friends algorithms are a common tool to detect galaxy groups and clusters in large survey data. In order to be as precise as possible, they have to be carefully calibrated using mock catalogues. We create an accurate and robust description of the matter distribution in the local Universe using the most up-to-date available data. This will provide the input for a specific cosmological test planned as follow-up to this work, and will be useful for general extragalactic and cosmological research. We create a set of galaxy group catalogues based on the 2MRS (Huchra et al., 2012, Cat. J/ApJS/199/26) and SDSS DR12 galaxy samples using a friends-of-friends based group finder algorithm. The algorithm is carefully calibrated and optimised on a new set of wide-angle mock catalogues from the Millennium simulation, in order to provide accurate total mass estimates of the galaxy groups taking into account the relevant observational biases in 2MRS and SDSS. We provide four different catalogues: (i) a 2MRS based group catalogue; (ii) a SDSS DR12 based group catalogue reaching out to a redshift z=0.11 with stellar mass estimates for 70% of the galaxies; (iii) a catalogue providing additional fundamental plane distances for all groups of the SDSS catalogue that host elliptical galaxies; (iv) a catalogue of the mass distribution in the local Universe based on a combination of our 2MRS and SDSS catalogues. While motivated by a specific cosmological test, three of the four catalogues that we produced are well suited to act as reference databases for a variety of extragalactic and cosmological science cases. Our catalogue of fundamental plane distances for SDSS groups provides further added value to this paper.
