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- ID:
- ivo://CDS.VizieR/J/MNRAS/391/297
- Title:
- Radio Survey of 7 X-ray Clusters of Galaxies
- Short Name:
- J/MNRAS/391/297
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Australia Telescope Compact Array (ATCA) has been used at 1.38 and 2.38GHz to survey seven southern Abell clusters of galaxies with high X-ray luminosities: A2746, A2837, A3126, A3216, A3230, A3827 and A3836. The clusters have also been surveyed at 0.843GHz with the Molonglo Observatory Synthesis Telescope (MOST). We have listed a complete 1.38-GHz sample of 149 radio sources within the Abell circles centred on their X-ray centroids. We compare their identification fractions, emitted 1.38-GHz and optical powers, radio spectral indices and radial variation in projected source density with those of the radio-selected samples of Slee et al. (1998AuJPh..51..971S). We compare our fractional radio luminosity function with that of the radio-selected samples of Ledlow and Owen (1996AJ....112....9L) and Slee et al. (1998AuJPh..51..971S). Three significant differences are noted between X-ray and radio-selected samples of clusters; (1) the X-ray sample has an excess of flat-spectrum radio sources; (2) the fractional radio luminosity function for the FR I sources in the X-ray selected sample is much steeper, implying that fewer of their cluster galaxies become hosts for the stronger FR I radio galaxies; (3) a complete absence of FR II radio galaxies in the X-ray selected sample. The average excess projected density of radio sources near our cluster centres is approx. 5 times the background source density.
- ID:
- ivo://CDS.VizieR/J/A+A/631/A114
- Title:
- Ram pressure in cluster galaxies a z=0.7
- Short Name:
- J/A+A/631/A114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- MUSE observations of the cluster of galaxies CGr32 (M200~2x10^14^M_{sun}_) at z=0.73 reveal the presence of two massive star forming galaxies with extended tails of diffuse gas detected in the [OII]3727-3729{AA} emission- line doublet. The tails, which have a cometary shape with a typical surface brightness of a few 10^-18^erg/s/cm^2^/arcsec^2^, extend up to ~100kpc (projected distance) from the galaxy discs and are not associated to any stellar component. All this observational evidence suggests that the gas has been removed during a ram-pressure stripping event. This observation is thus the first evidence that dynamical interactions with the intracluster medium were active when the Universe had only half of its present age. The density of the gas derived using the observed [OII]3729/[OII]3726 line ratio implies a very short recombination time, suggesting that a source of ionisation is necessary to keep the gas ionised within the tail.
- ID:
- ivo://CDS.VizieR/J/ApJ/534/114
- Title:
- RASSCALS: X-ray and optical study
- Short Name:
- J/ApJ/534/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the ROSAT All-Sky Survey Center for Astrophysics Loose Systems (RASSCALS), the largest X-ray and optical survey of low-mass galaxy groups to date. We draw 260 groups from the combined Center for Astrophysics and Southern Sky Redshift Surveys, covering one-quarter of the sky to a limiting Zwicky magnitude of m_z_=15.5.
- ID:
- ivo://CDS.VizieR/J/ApJS/140/239
- Title:
- RASS: clusters of galaxies around SGP
- Short Name:
- J/ApJS/140/239
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A field of 1.013sr in the ROSAT All-Sky Survey (RASS), centered on the south Galactic pole (SGP), has been searched in a systematic, objective manner for clusters of galaxies. The procedure relied on a correlation of the X-ray positions and properties of ROSAT sources in the field with the distribution of galaxies in the COSMOS digitized database, which was obtained from scanning the plates of the UK Schmidt IIIa-J optical survey of the southern sky. The study used the second ROSAT survey database (RASS-2) and included several optical observing campaigns to measure cluster redshifts. The search, which is a precursor to the larger REFLEX survey encompassing the whole southern sky, reached the detection limits of both the RASS and the COSMOS data and yielded a catalog of 186 clusters in which the lowest flux is 1.5x10-12ergs/cm^2^/s in the 0.1-2.4keV band. Of these 157 have measured redshifts. Using a flux limit of 3.0x10-12ergs/cm^2^/s a complete subset of 112 clusters was obtained, of which 110 have measured redshifts. The spatial distribution of the X-ray clusters out to a redshift of 0.15 shows an extension of the Local Supercluster to the Pisces-Cetus supercluster (z<0.07), and an orthogonal structure at higher redshift (0.07<z<0.15). This result is consistent with large-scale structure suggested by optical surveys.
- ID:
- ivo://CDS.VizieR/J/A+A/423/449
- Title:
- RASS-SDSS Galaxy Clusters Survey. I.
- Short Name:
- J/A+A/423/449
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The tables list the optical and X-rays properties of the RASS-SDSS galaxy clusters catalog. The catalog contains 114 X-ray selected systems in the area observed by the Sloan Digital Sky Survey (SDSS). The X-ray data are taken from the ROSAT All Sky Survey (RASS, <IX/10>) while the optical data are taken from the SDSS (<J/AJ/123/567>) archive.
- ID:
- ivo://CDS.VizieR/J/A+A/461/397
- Title:
- RASS-SDSS galaxy cluster survey. V.
- Short Name:
- J/A+A/461/397
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we consider a large sample of optically selected clusters, in order to elucidate the physical reasons for the existence of X-ray underluminous clusters. For this purpose we analyzed the correlations of the X-ray and optical properties of a sample of 137 spectroscopically confirmed Abell clusters in the SDSS database. We searched for the X-ray counterpart of each cluster in the ROSAT All Sky Survey. We find that 40% of our clusters have a marginal X-ray detection or remain undetected in X-rays. These clusters appear too X-ray faint on average for their mass as determined by velocity dispersion; i.e. they do not follow the scaling relation between X-ray luminosity and virial mass traced by the other clusters. On the other hand, they do follow the general scaling relation between optical luminosity and virial mass. We refer to these clusters as the X-ray-underluminous Abell clusters (AXU clusters, for short) and designate as "normal" the X-ray detected Abell systems. We separately examined the distributions and properties of the galaxy populations of the normal and the AXU clusters.
- ID:
- ivo://CDS.VizieR/J/A+A/459/679
- Title:
- RB photometry of LSBG in Coma
- Short Name:
- J/A+A/459/679
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on a search for faint (R total magnitude fainter than 21) and low surface brightness galaxies (R central surface brightness fainter than ~24) (fLSBs) in a 0.72x0.82deg^2^ area centered on the Coma cluster. We analyzed deep B and R band CCD imaging obtained using the CFH12K camera at CFHT and found 735 fLSBs. The total B magnitudes, at the Coma cluster redshift, range from -13 to -9 with B central surface brightness as faint as 27mag/arcsec^2^.
- ID:
- ivo://CDS.VizieR/J/AJ/135/1488
- Title:
- Rc photometry of galaxies in NGC 5353/4 group
- Short Name:
- J/AJ/135/1488
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This third paper in a series about the dwarf galaxy populations in groups within the Local Supercluster concerns the intermediate mass (2.1x10^13^M_{sun}_) NGC 5353/4 Group with a core dominated by S0 systems and a periphery of mostly spiral systems. Dwarf galaxies are strongly concentrated toward the core. The mass-to-light ratio M/L_R_=105M_{sun}_/L_{sun}_ is a factor of 3 lower than for the two groups studied earlier in the series. The properties of the group suggest it is much less dynamically evolved than those two groups of early-type galaxies. By comparison, the NGC 5353/4 Group lacks superluminous systems but has a large fraction of intermediate-luminosity galaxies; or equivalently, a luminosity function with a flatter faint-end slope. The luminosity function for the NGC 5353/4 Group should steepen as the intermediate-luminosity galaxies merge. Evidence for the ongoing collapse of the group is provided by the unusually large incidence of star-formation activity in small galaxies with early morphological types. The pattern in the distribution of galaxies with activity suggests a succession of infall events. Residual gas in dwarfs that enter the group is used up in sputtering events. The resolution of midlife crises is exhaustion.
- ID:
- ivo://CDS.VizieR/J/ApJS/238/32
- Title:
- 3rd MAXI/GSC X-ray cat at high Galactic latitude
- Short Name:
- J/ApJS/238/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the third MAXI/GSC catalog in the high Galactic latitude sky (|b|>10{deg}) based on the 7-year data from 2009 August 13 to 2016 July 31, complementary to that in the low Galactic latitude sky (|b|<10{deg}) (Hori+ 2018ApJS..235....7H). We compile 682 sources detected at significances of s_D,4-10keV_>=6.5 in the 4-10keV band. A two-dimensional image fit based on the Poisson likelihood algorithm (C-statistics) is adopted for the detections and constraints on their fluxes and positions. The 4-10keV sensitivity reaches ~0.48mCrab, or ~5.9x10^-12^erg/cm^2^/s, over half of the survey area. Compared with the 37-month Hiroi+ (2013, J/ApJS/207/36) catalog, which adopted a threshold of s_D,4-10keV_>=7, the source number increases by a factor of ~1.4. The fluxes in the 3-4keV and 10-20keV bands are further estimated, and hardness ratios (HRs) are calculated using the 3-4keV, 4-10keV, 3-10keV, and 10-20keV band fluxes. We also make the 4-10keV light curves in 1-year bins for all the sources and characterize their variabilities with an index based on a likelihood function and the excess variance. Possible counterparts are found from five major X-ray survey catalogs by Swift, Uhuru, RXTE, XMM-Newton, and ROSAT, as well as an X-ray galaxy cluster catalog (MCXC). Our catalog provides the fluxes, positions, detection significances, HRs, 1-year bin light curves, variability indices, and counterpart candidates.
