- ID:
- ivo://CDS.VizieR/J/MNRAS/442/2216
- Title:
- Redshifts of galaxies in Abell 1351 field
- Short Name:
- J/MNRAS/442/2216
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim to review the internal structure and dynamics of the Abell 1351 cluster, shown to host a radio halo with a quite irregular shape. Our analysis is based on radial velocity data for 135 galaxies obtained at the Telescopio Nazionale Galileo. We combine galaxy velocities and positions to select 95 cluster galaxy members and analyse the internal dynamics of the whole cluster. We also examine X-ray data retrieved from Chandra and XMM archives. We measure the cluster redshift, <z>=0.325, the line-of-sight (LOS) velocity dispersion, {sigma}V~1500km/s, and the X-ray temperature, kT~9keV. From both X-ray and optical data independently, we estimate a large cluster mass, in the 1-4x10^15^h_70_^-1^M_{sun}_. We attribute the extremely high value of {sigma}V to the bimodality in the velocity distribution. We find evidence of a significant velocity gradient and optical 3D substructure. The X-ray analysis also shows many features in favour of a complex cluster structure, probably supporting an ongoing merger of substructures in Abell 1351. The observational scenario agrees with the presence of two main subclusters in the northern region, each with its brightest galaxy (BCG1 and BCG2), detected as the two most important X-ray substructures with a rest-frame LOS velocity difference of {Delta}V_rf_~2500km/s and probably being in large part aligned with the LOS. We conclude that Abell 1351 is a massive merging cluster. The details of the cluster structure allow us to interpret the quite asymmetric radio halo as a 'normal' halo plus a southern relic, strongly supporting a previous suggestion based only on inspection of radio and preliminary X-ray data.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/425/429
- Title:
- Redshifts of 119 galaxies in ACO 1367
- Short Name:
- J/A+A/425/429
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Redshifts of 119 galaxies in the Abell cluster 1367 are presented. The majority (98) were obtained with the AF2-WYFFOS multi fiber spectrograph at the 4.2m William Herschel Telescope (WHT). Nine additional long-slit, low dispersion spectra were obtained using the imaging spectrograph BFOSC attached to the Cassini 1.5m telescope at Loiano. Another twelve spectra were taken with LFOSC at the 2.1m telescope of the Guillermo Haro Observatory at Cananea.
- ID:
- ivo://CDS.VizieR/J/A+A/435/781
- Title:
- Redshifts of galaxies in 21 EIS cluster fields
- Short Name:
- J/A+A/435/781
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carried out an investigation of the properties of low redshift EIS clusters using both spectroscopy and imaging data. We present new redshifts for 738 galaxies in 21 ESO Imaging Survey (EIS) Cluster fields. We use the "gap"-technique to search for significant overdensities in redshift space and to identify groups/clusters of galaxies corresponding to the original EIS matched filter cluster candidates. In this way we spectroscopically confirm 20 of the 21 cluster candidates with a matched-filter estimated redshift z_MF_=0.2. We have now obtained spectroscopic redshifts for 34 EIS cluster candidates with z_MF_=0.2 (see also Hansen et al., 2002, Cat. <J/A+A/388/1>; Olsen et al., 2003, Cat. <J/A+A/409/439>. Of those we spectroscopically confirm 32 with redshifts ranging from z=0.064 to 0.283. We find that: 1) the velocity dispersions of the systems range from sigma_v_<=130km/s to sigma_v_=1200km/s, typical of galaxy groups to rich clusters; 2) richnesses corresponding to Abell classes R<=1; and 3) concentration indices ranging from C=0.2 to C=1.2. From the analysis of the colours of the galaxy populations we find that 53% of the spectroscopically confirmed systems have a "significant" red sequence. These systems are on average richer and have higher velocity dispersions. We find that the colour of the red sequence galaxies matches passive stellar evolution predictions.
- ID:
- ivo://CDS.VizieR/J/ApJ/658/865
- Title:
- Redshifts of galaxies in X-ray-luminous groups
- Short Name:
- J/ApJ/658/865
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the galaxy populations in seven X-ray-selected, intermediate-redshift groups (0.2<z<0.6). Overall, the galaxy populations in these systems are similar to those in clusters at the same redshift; they have large fractions of early-type galaxies (fe~70%) and small fractions of galaxies with significant star formation (f~30%).
- ID:
- ivo://CDS.VizieR/J/AJ/131/1280
- Title:
- Redshifts of HRS galaxies
- Short Name:
- J/AJ/131/1280
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 118 new optical redshifts for galaxies in 12 clusters in the Horologium-Reticulum supercluster (HRS) of galaxies. For 76 galaxies, the data were obtained with the Dual Beam Spectrograph on the 2.3m telescope of the Australian National University at Siding Spring Observatory. After combining 42 previously unpublished redshifts with our new sample, we determine mean redshifts and velocity dispersions for 13 clusters in which previous observational data were sparse.
- ID:
- ivo://CDS.VizieR/J/ApJ/888/35
- Title:
- Redshifts of lensed systems toward RXCJ2248.7-4431
- Short Name:
- J/ApJ/888/35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an iterative method to construct a freeform lens model that self-consistently reproduces the sky positions, geometrically inferred redshifts, and relative brightnesses of all multiply lensed images toward a galaxy cluster. This method is applied to the cluster RXCJ2248.7-4431 (z=0.348) from the Hubble Frontier Fields program, toward which 10 multiply lensed sources with accurate spectroscopic redshifts and 6 others with inexact photometric redshifts have been identified. Using the spectroscopically secure systems to define an initial lens model, we compute the geometric redshifts of the photometric systems. We then iterate the lens model by incorporating the photometric systems at redshifts shifted by incremental amounts toward their geometric redshifts inferred from the previous step; on convergence, we find geometric redshifts in good agreement with the spectroscopically determined redshifts, but they can depart significantly from the photometrically determined redshifts. In the final lens model, all 16 lensed sources tightly follow the cosmological form of the angular diameter distance relation. Furthermore, although they are not used as model constraints, our lens model predicts relative brightnesses between image pairs for a given set of multiply lensed images in reasonable agreement with observations, thus providing independent validation of this model.
- ID:
- ivo://CDS.VizieR/J/MNRAS/316/326
- Title:
- Redshifts of Ophiuchus region galaxies
- Short Name:
- J/MNRAS/316/326
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The large-scale structure around the Ophiuchus cluster of galaxies in the vicinity of the Galactic Centre (l=0.5{deg}, b=9.5{deg}, cz=8500km/s) is investigated on the basis of a galaxy survey and spectroscopic observations made for a 120{deg}x170{deg} area. The galaxy survey was performed using six ESO/SERC Sky Survey Atlas films, and 4021 galaxies were detected in total. Recession velocities were newly obtained for 179 galaxies to make the total number of galaxies in the survey area with known velocities 219. In the distribution of bright galaxies, we identified seven new clumps of galaxies. Comparing the surface number density of bright galaxies with the Galactic extinction, which is estimated from the 100-{mu}m flux density in the IRAS Sky Survey Atlas, we demonstrate that the seven clumps are not spurious as a result of the inhomogeneity of the Galactic extinction. Among the seven clumps, two are found to be clusters and four to be groups on the basis of the histogram of recession velocities and the number of member galaxies. The Ophiuchus cluster, two newly identified clusters, and four groups are all concentrated at 9000km/s. Field galaxies are also distributed centred at 8500km/s. Hence field galaxies occupy a common three-dimensional region with galaxies in the clusters and groups, and altogether they form a large-scale structure of supercluster size. As opposed to the overdensity in the supercluster region, the mean number density of galaxies in the velocity range 0-5000km/s is only 25 per cent of the mean number density of the Universe, comparable with the density of the well-known Bootes void. Hence this nearby three-dimensional region in Ophiuchus is a void of galaxies also.
- ID:
- ivo://CDS.VizieR/J/AJ/123/3018
- Title:
- Redshifts of radio-selected poor clusters
- Short Name:
- J/AJ/123/3018
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Multifiber optical spectroscopy has been performed on galaxies in the vicinity of strong, nearby radio galaxies. These radio galaxies were selected from the 3CR and B2 catalogs based on their exclusion from the Abell catalog, which is puzzling given the hypothesis that an external medium is required to confine the radio plasma of such galaxies. Velocities derived from the spectra were used to confirm the existence of groups and poor clusters in the fields of most of the radio galaxies. We find that all radio galaxies with classical Fanaroff-Riley type I morphologies prove to reside in clusters, whereas the other radio galaxies often appear to be recent galaxy-galaxy mergers in regions of low galaxy density. These findings confirm the earlier result that the existence of extended X-ray emission combined with a statistical excess of neighboring galaxies can be used to identify poor clusters associated with radio galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJS/96/343
- Title:
- Redshifts of rich clusters of galaxies
- Short Name:
- J/ApJS/96/343
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present spectroscopic observations and accurate positions for 286 galaxies in clusters taken over several observing sessions, mostly with the DuPont telescope at Las Campanas Observatorv. We derive 165 redshifts of rich clusters of which 130 are apparently new values. Redshifts encompass a wide range out to z=0.27
- 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.
