- ID:
- ivo://CDS.VizieR/J/MNRAS/274/75
- Title:
- Redshifts of ROSAT X-ray brightest clusters
- Short Name:
- J/MNRAS/274/75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report results from the second stage of an optical follow-up study aimed at determining new redshifts for clusters of galaxies selected from the ROSAT All-Sky Survey. We review the optical properties of all the clusters obtained so far in this programme, which comprises 71 clusters up to a redshift of 0.3. The fraction of central galaxies exhibiting optical line emission and an excess blue continuum is 34%, consistent with smaller, previous, X-ray samples. There is no trend for this fraction to increase with redshift, although we find a clear tendency for the strongest line emitters to have the bluest continua. The probability of the presence of line emission and an excess blue continuum is increased for those galaxies with associated radio sources, although the strength of these features does not appear to be related to the power of the radio emission.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+AS/101/259
- Title:
- Redshifts of southern rich clusters
- Short Name:
- J/A+AS/101/259
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/MNRAS/283/367
- Title:
- Redshift survey in Per-Psc and Pav-Ind
- Short Name:
- J/MNRAS/283/367
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The list of the measured galaxies is given in Table 3 together with COSMOS coordinates and apparent magnitude. These parameters (plus diameter, axis ratio and position angle) were used to perform cross-identification with the PGC/LEDA objects after reduction to the RC3 system (de Vaucouleurs et al., 1990, see cat. <VII/155>). Both cross correlation results (from `rvsao') and emission line results (from `emsao') are presented. A few galaxies with published redshifts were also observed to derive our external error (see section 3 of the paper).
- ID:
- ivo://CDS.VizieR/J/MNRAS/367/1261
- Title:
- Redshift survey in 15 quasar fields
- Short Name:
- J/MNRAS/367/1261
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the relative distribution of the gaseous contents of the Universe (as traced by a sample of Ly{alpha} absorbers), and the luminous baryonic matter (as traced by a redshift survey of galaxies in the same volume searched for Ly{alpha} absorbers), along 16 lines of sight (LOS) between redshifts 0 and 1. Our galaxy redshift survey was made with the multi-object spectrograph on the Canada-France-Hawaii Telescope and, when combined with galaxies from the literature in the same LOS, gives us a galaxy sample of 636 objects. By combining this with an absorption-line sample of 406 absorbing systems drawn from published works, we are able to study the relationship between gas and galaxies over the latter half of the age of the Universe.
- ID:
- ivo://CDS.VizieR/J/A+AS/109/537
- Title:
- Redshift survey of faint galaxies
- Short Name:
- J/A+AS/109/537
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/MNRAS/312/540
- Title:
- Redshift survey of intercluster galaxies
- Short Name:
- J/MNRAS/312/540
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a redshift survey of intercluster galaxies in the central region of the Shapley Concentration supercluster, aimed at determining the distribution of galaxies in between obvious overdensities. Our sample is formed by 442 new redshifts, mainly in the b_J_ magnitude range 17-18.8. Adding the data from our redshift surveys on the A3558 and A3528 complexes, which are close to the geometrical centre of this supercluster, we obtain a total sample of ~2000 radial velocities. The average velocity of the observed intercluster galaxies in the Shapley Concentration appears to be a function of their ({alpha}, {delta} position, and it can be fitted by a plane in the three dimensional space ({alpha}, {delta}, v): the distribution of the galaxy distances around the best-fitting plane is described by a Gaussian with dispersion 3.8h^-1^Mpc.
- ID:
- ivo://CDS.VizieR/J/A+AS/128/153
- Title:
- Revised GB/GB2 sample of radio sources
- Short Name:
- J/A+AS/128/153
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The revised sample of 373 extragalactic radio sources brighter than 0.2 Jy at 1.4GHz is presented. These sources, selected from the finding Green Bank surveys, were mapped at 1465 MHz using the VLA at different configurations. The biases introduced into the original GB (Maslowski, 1972AcA....22..227M) and GB2 (Machalski, 1978AcA....28..367M) catalogues by confusion as well as partial resolution by the VLA at its A-configuration, are eliminated. In effect, a number of sources have been excluded, and a few other are included into the revised sample. Now the sample is about 99, 97 and 95 per cent complete for sources with S_1.4_>=0.55Jy, 0.25Jy<=S_1.4_<0.55Jy, and 0.2Jy<=S_1.4_<0.25Jy, respectively. Table 3 gives the compilation of the radio, optical, and X-ray data available for the sample sources.
- ID:
- ivo://CDS.VizieR/II/326
- Title:
- Revised SWIRE photometric redshifts
- Short Name:
- II/326
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have revised the Spitzer Wide-Area Infrared Extragalactic survey (SWIRE) Photometric Redshift Catalogue to take account of new optical photometry in several of the SWIRE areas, and incorporating Two Micron All Sky Survey (2MASS) and UKIRT Infrared Deep Sky Survey (UKIDSS) near-infrared data. Aperture matching is an important issue for combining near-infrared and optical data, and we have explored a number of methods of doing this. The increased number of photometric bands available for the redshift solution results in improvements both in the rms error and, especially, in the outlier rate. We have also found that incorporating the dust torus emission into the quasi-stellar object (QSO) templates improves the performance for QSO redshift estimation. Our revised redshift catalogue contains over 1 million extragalactic objects, of which 26 288 are QSOs.
- ID:
- ivo://CDS.VizieR/J/MNRAS/308/233
- Title:
- RIXOS source sample X-ray spectra
- Short Name:
- J/MNRAS/308/233
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of an extensive study of the X-ray spectral properties of sources detected in the RIXOS survey, which is a large, nearly complete sample of objects detected serendipitously in ROSAT PSPC fields down to a flux limit of 3x10^-14^erg/cm2/s (0.5-2keV). We show that for X-ray surveys containing sources with low count rate, such as RIXOS, spectral slopes estimated using simple hardness ratios in the ROSAT band can be biased. Instead, we analyse three-colour X-ray data using statistical techniques appropriate to the Poisson regime which remove the effects of this bias. We also show that the use of three-colour data enables some discrimination between thermal and non-thermal spectra. We have then applied this technique to the RIXOS survey to study the spectral properties of the sample. For the AGN we find an average energy index of 1.05+/-0.05, with no evidence for spectral evolution with redshift. Individual AGN are shown to have a range of properties, including soft X-ray excesses and intrinsic absorption. Narrow-emission-line galaxies (NLLGs) also seem to fit to a power-law spectrum, which may indicate a non-thermal origin for their X-ray emission. We infer that most of the clusters in the sample have a bremsstrahlung temperature >3keV, although some show evidence for a cooling flow. The stars deviate strongly from a power-law model but fit to a thermal model. Finally, we have analysed the whole RIXOS sample (extending the flux cut-off to the sensitivity threshold of each individual observation) containing 1762 sources to study the relationship between spectral slope and flux. We find that the mean spectral slope of the sources hardens at lower fluxes, in agreement with results from other samples. However, a study of the individual sources demonstrates that the majority have relatively soft spectra even at faint flux levels, and the hardening of the mean is caused by the appearance of a population of very hard sources at the lowest fluxes. This has implications for the nature of the soft X-ray background.
- ID:
- ivo://CDS.VizieR/J/MNRAS/418/2074
- Title:
- Robust sample of galaxies at 6.0<z<8.7
- Short Name:
- J/MNRAS/418/2074
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a photometric redshift analysis designed to identify z>=6 galaxies from the near-infrared Hubble Space Telescope imaging in three deep fields [Hubble Ultra Deep Field (HUDF), HUDF09-2 and Early Release Science] covering a total area of 45 square arcmin. By adopting a rigorous set of criteria for rejecting low-redshift interlopers, and by employing a deconfusion technique to allow the available ultradeep IRAC imaging to be included in the candidate-selection process, we have derived a robust sample of 70 Lyman break galaxies (LBGs) spanning the redshift range 6.0<z<8.7.
