- ID:
- ivo://CDS.VizieR/J/A+A/409/439
- Title:
- Redshifts of 11 EIS clusters
- Short Name:
- J/A+A/409/439
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of carrying out multi-object spectroscopy in 10 EIS cluster fields. Based on the list of 345 galaxy redshifts we identify significant 3D-density enhancements. For 9 of the EIS clusters we identify significant 3D-concentrations corresponding to the originally detected cluster candidate. We find redshifts in the range 0.097<=z<=0.257 which is in good agreement with the matched filter estimate of z_MF_=0.2. We estimate velocity dispersions in the range 219-1160km/s for the confirmed clusters
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/388/1
- Title:
- Redshifts of five EIS clusters
- Short Name:
- J/A+A/388/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of the first multi-object spectroscopic observations at the Danish 1.54m telescope at La Silla, Chile. Observations of five cluster candidates from The ESO Imaging Survey Cluster Candidate Catalog are described. From these observations we confirm the reality of the five clusters with measured redshifts of 0.11<=z<=0.35. We estimate velocity dispersions in the range 294-621km/s indicating rather poor clusters. This, and the measured cluster redshifts are consistent with the results of the matched filter procedure applied to produce the Cluster Candidate Catalog.
- ID:
- ivo://CDS.VizieR/J/A+A/468/807
- Title:
- Redshifts of galaxies associated with X emission
- Short Name:
- J/A+A/468/807
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of spectroscopic observations of galaxies associated with the diffuse X-ray emitting structure discovered by Zappacosta et al. (2002A&A...394....7Z). After measuring the redshifts of 161 galaxies, we confirm an overdensity of galaxies with projected dimensions of at least 2Mpc, determine its spectroscopic redshift in z=0.401+/-0.002, and show that it is spatially coincident with the diffuse X-ray emission. This confirms the original claim that this X-ray emission has an extragalactic nature and is due to the warm-hot intergalactic medium (WHIM). We used this value of the redshift to compute the temperature of the emitting gas. The resulting value depends on the metallicity that is assumed for the IGM, and is constrained to be between 0.3 and 0.6keV for metallicities between 0.05 and 0.3solar, in good agreement with the expectations from the WHIM.
- ID:
- ivo://CDS.VizieR/J/ApJ/781/2
- Title:
- Redshifts of 1151 galaxies from SDSS
- Short Name:
- J/ApJ/781/2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Lines of sight with multiple projected cluster-scale gravitational lenses have high total masses and complex lens plane interactions that can boost the area of magnification, or etendue, making detection of faint background sources more likely than elsewhere. To identify these new "compound" cosmic telescopes, we have found directions in the sky with the highest integrated mass densities, as traced by the projected concentrations of luminous red galaxies (LRGs). We use new galaxy spectroscopy to derive preliminary magnification maps for two such lines of sight with total mass exceeding ~3x10^15^M_{sun}_. From 1151 MMT Hectospec spectra of galaxies down to i_AB_=21.2, we identify two to three group- and cluster-scale halos in each beam. These are well traced by LRGs. The majority of the mass in beam J085007.6+360428 (0850) is contributed by Zwicky 1953, a massive cluster at z=0.3774, whereas beam J130657.5+463219 (1306) is composed of three halos with virial masses of 6x10^14^-2x10^15^M_{sun}_, one of which is A1682. The magnification maps derived from our mass models based on spectroscopy and Sloan Digital Sky Survey photometry alone display substantial etendue: the 68% confidence bands on the lens plane area with magnification exceeding 10 for a source plane of z_s_=10 are [1.2,3.8]arcmin^2^ for 0850 and [2.3,6.7]arcmin^2^ for 1306. In deep Subaru Suprime-Cam imaging of beam 0850, we serendipitously discover a candidate multiply imaged V-dropout source at z_phot_=5.03. The location of the candidate multiply imaged arcs is consistent with the critical curves for a source plane of z=5.03 predicted by our mass model. Incorporating the position of the candidate multiply imaged galaxy as a constraint on the critical curve location in 0850 narrows the 68% confidence band on the lens plane area with {mu}>10 and z_s_=10 to [1.8,4.2]arcmin^2^, an etendue range comparable to that of MACS 0717+3745 and El Gordo, two of the most powerful single cluster lenses known. The significant lensing power of our beams makes them powerful probes of reionization and galaxy formation in the early universe.
- 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/A+A/618/A66
- Title:
- Redshifts of obscured AGN
- Short Name:
- J/A+A/618/A66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Redshifts are fundamental for our understanding of extragalactic X-ray sources. Ambiguous counterpart associations, expensive optical spectroscopy and/or multimission multiwavelength coverage to resolve degeneracies make estimation often difficult in practice. We attempt to constrain redshifts of obscured Active Galactic Nuclei (AGN) using only low-resolution X-ray spectra. Our XZ method fits AGN X-ray spectra with a moderately complex spectral model incorporating a corona, torus obscurer and warm mirror. Using the Bayesian X-ray Astronomy (BXA) package, we constrain redshift, column density, photon index and luminosity simultaneously. The redshift information primarily comes from absorption edges in Compton-thin AGN, and from the Fe K{alpha} fluorescent line in heavily obscured AGN. A new generic background fitting method allows us to extract more information from limited numbers of source counts. We derive redshift constraints for 74/321 hard-band detected sources in the Chandra deep field South. Comparing with spectroscopic redshifts, we find an outlier fraction of 8%, indicating that our model assumptions are valid. For three Chandra deep fields, we release our XZ redshift estimates. The independent XZ estimate is easy to apply and effective for a large fraction of obscured AGN in todays deep surveys without the need for any additional data. Comparing to different redshift estimation methods, XZ can resolve degeneracies in photometric redshifts, help to detect potential association problems and confirm uncertain single-line spectroscopic redshifts. With high spectral resolution and large collecting area, this technique will be highly effective for Athena/WFI observations.