- ID:
- ivo://CDS.VizieR/J/AJ/153/220
- Title:
- NORAS II. I. First results
- Short Name:
- J/AJ/153/220
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As the largest, clearly defined building blocks of our universe, galaxy clusters are interesting astrophysical laboratories and important probes for cosmology. X-ray surveys for galaxy clusters provide one of the best ways to characterize the population of galaxy clusters. We provide a description of the construction of the NORAS II galaxy cluster survey based on X-ray data from the northern part of the ROSAT All-Sky Survey. NORAS II extends the NORAS survey down to a flux limit of 1.8x10^-12^erg/s/cm^2^ (0.1-2.4keV), increasing the sample size by about a factor of two. The NORAS II cluster survey now reaches the same quality and depth as its counterpart, the southern REFLEX II survey, allowing us to combine the two complementary surveys. The paper provides information on the determination of the cluster X-ray parameters, the identification process of the X-ray sources, the statistics of the survey, and the construction of the survey selection function, which we provide in numerical format. Currently NORAS II contains 860 clusters with a median redshift of z=0.102. We provide a number of statistical functions, including the log N-log S and the X-ray luminosity function and compare these to the results from the complementary REFLEX II survey. Using the NORAS II sample to constrain the cosmological parameters, {sigma}_8_ and {Omega}_m_, yields results perfectly consistent with those of REFLEX II. Overall, the results show that the two hemisphere samples, NORAS II and REFLEX II, can be combined without problems into an all-sky sample, just excluding the zone of avoidance.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/125/2064
- Title:
- Northern Optical Cluster Survey. II.
- Short Name:
- J/AJ/125/2064
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new, objectively defined catalog of candidate galaxy clusters based on the galaxy catalogs from the digitized Second Palomar Observatory Sky Survey. This cluster catalog, derived from the best calibrated plates in the high-latitude (|b|>30{deg}) northern Galactic cap region, covers 5800deg^2^ and contains 8155 candidate clusters. A simple adaptive kernel density mapping technique, combined with the SExtractor object detection algorithm, is used to detect galaxy overdensities, which we identify as clusters. Simulations of the background galaxy distribution and clusters of varying richnesses and redshifts allow us to optimize detection parameters and measure the completeness and contamination rates for our catalog. Cluster richnesses and photometric redshifts are measured, using integrated colors and magnitudes for each cluster. An extensive spectroscopic survey is used to confirm the photometric results. This catalog, with well-characterized sample properties, provides a sound basis for future studies of cluster physics and large-scale structure.
- ID:
- ivo://CDS.VizieR/J/AJ/137/2981
- Title:
- Northern Optical Cluster Survey. III.
- Short Name:
- J/AJ/137/2981
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the complete galaxy cluster catalog from the Northern Sky Optical Cluster Survey, a new, objectively defined catalog of candidate galaxy clusters at z<~0.25 drawn from the Digitized Second Palomar Observatory Sky Survey (DPOSS). The data presented here cover the Southern Galactic Cap, as well as the less well-calibrated regions of the Northern Galactic Cap. In addition, due to improvements in our cluster finder and measurement methods, we provide an updated catalog for the well-calibrated Northern Galactic Cap region previously published in Paper II (Cat. J/AJ/125/2064). The complete survey covers 11411deg^2^, with over 15000 candidate clusters.
- ID:
- ivo://CDS.VizieR/J/AJ/128/1017
- Title:
- Northern Optical Cluster Survey. IV.
- Short Name:
- J/AJ/128/1017
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an optically selected galaxy cluster catalog from 2700{deg}^2^ of the digitized Second Palomar Observatory Sky Survey (DPOSS), spanning the redshift range 0.1~<z~<0.5, providing an intermediate-redshift supplement to the previous DPOSS cluster survey. This new catalog contains 9956 cluster candidates and is the largest resource of rich clusters in this redshift range to date.
- ID:
- ivo://CDS.VizieR/J/MNRAS/363/1019
- Title:
- Nucleated dwarf ellipticals in Virgo cluster
- Short Name:
- J/MNRAS/363/1019
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using images from a charge-coupled device survey with the Wide Field Camera on the Isaac Newton Telescope, we performed B- and I-band photometry on 156 Virgo cluster dwarf elliptical (dE) galaxies, 25 candidate new cluster dwarfs, and nine candidate field dwarfs.
- ID:
- ivo://CDS.VizieR/J/A+A/581/A41
- Title:
- OmegaWINGS BV photometry of galaxy clusters
- Short Name:
- J/A+A/581/A41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The WIde-field Nearby Galaxy-cluster Survey (WINGS) is a wide-field and multiwavelength survey of 76 galaxy clusters in the local Universe. The sample consists of all clusters at 0.04<z<0.07 in both hemispheres at Galactic latitude |b|>20 selected from the ROSAT X-ray-Brightest Abell-type Cluster Sample, the Brightest Cluster Sample, and its extension. The original WINGS survey is based on B and V imaging for the 76 clusters over a 34 by 34 arcminute field of view taken with the Wide Field Cameras on the INT and the 2.2m MPG/ESO telescopes. With the aim to cover the virial region and extend out into the infall region, we have obtained GTO OmegaCAM imaging in the B, and V bands over 1 by 1 degree for 45 fields covering 46 WINGS clusters. We present the Johnson B- and V-band OmegaCAM photometry of 46 WINGS clusters. With a median seeing of 1 arcsecond in both B- and V-bands, our 25-minutes exposures in each band typically reach the 50% completeness level at V=23.1mag.
- ID:
- ivo://CDS.VizieR/J/A+A/599/A81
- Title:
- OmegaWINGS local clusters of galaxies redshifts
- Short Name:
- J/A+A/599/A81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the spectroscopic follow-up of the OmegaWINGS photometric survey, aimed at covering the outskirts of a subset of the original WINGS cluster sample. We observed 33 of the 46 clusters of galaxies observed with VST over 1 square degree. The aim of this spectroscopic survey is to enlarge the number of cluster members and study the galaxy characteristics and the cluster dynamical properties out to large radii, reaching the virial radius and beyond. We used the AAOmega spectrograph at AAT to obtain fiber-integrated spectra covering the wavelength region between 3800 and 9000{AA} with a spectral resolution of 3.5-6{AA} full width at half maximum (FWHM). We present here the redshift measurements for 17985 galaxies, 7497 of which turned out to be cluster members.
- ID:
- ivo://CDS.VizieR/J/ApJS/254/30
- Title:
- One-side head-tail (OHT) galaxies from FIRST & SDSS
- Short Name:
- J/ApJS/254/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- One-side head-tail (OHT) galaxies are radio galaxies with a peculiar shape. They usually appear in galaxy clusters, but they have never been cataloged systematically. We design an automatic procedure to search for them in the Faint Images of the Radio Sky at Twenty-Centimeters source catalog and compile a sample with 115 HT candidates. After cross-checking with the Sloan Digital Sky Survey photometric data and catalogs of galaxy clusters, we find that 69 of them are possible OHT galaxies. Most of them are close to the center of galaxy clusters. The lengths of their tails do not correlate with the projection distance to the center of the nearest galaxy clusters, but show weak anticorrelation with the cluster richness, and are inversely proportional to the radial velocity differences between clusters and host galaxies. Our catalog provides a unique sample to study this special type of radio galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/583/A124
- Title:
- Ophiuchus r'g'z' photometry and redshifts
- Short Name:
- J/A+A/583/A124
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Ophiuchus cluster, at a redshift z=0.0296, is known from X-rays to be one of the most massive nearby clusters, but due to its very low Galactic latitude its optical properties have not been investigated in detail. Aims. We discuss the optical properties of the galaxies in the Ophiuchus cluster, in particular with the aim of understanding better its dynamical properties. We have obtained deep optical imaging in several bands with various telescopes, and applied a sophisticated method to model and subtract the contributions of stars in order to measure galaxy magnitudes as accurately as possible. The colour-magnitude relations obtained show that there are hardly any blue galaxies in Ophiuchus (at least brighter than r'<=19.5), and this is confirmed by the fact that we only detect two galaxies in H{alpha}. We also obtained a number of spectra with ESO-FORS2, that we combined with previously available redshifts. Altogether, we have 152 galaxies with spectroscopic redshifts in the 0.02<=z<=0.04 range, and 89 galaxies with both a redshift within the cluster redshift range and a measured r' band magnitude (limited to the Megacam 1x1deg^2^ field).
- ID:
- ivo://CDS.VizieR/J/A+A/473/399
- Title:
- Optical and HI data of 6 southern galaxy groups
- Short Name:
- J/A+A/473/399
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Multi-wavelength observations of Hickson's Compact Groups (HCGs) have shown that many of these groups are physical bound structures and are in different stage of evolution, from spiral-dominated systems to almost merged objects. Very few studies have analysed the Southern Compact Groups (SCGs) sample, which is thought to be younger that HCGs, due to an on average higher number of spiral galaxies. We present here the first results from optical and radio observations on a pilot sample of SCGs. Optical observations of SCGs obtained with ESO telescopes and radio data from the ATCA allow us to probe the distribution of the warm intra-group medium and the evolutionary stage of each group, by means of morphological studies and via measurements of star formation and other types of nuclear activity.
