- ID:
- ivo://CDS.VizieR/J/ApJ/817/34
- Title:
- C-COSMOS Legacy sources multiwavelength catalog
- Short Name:
- J/ApJ/817/34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the catalog of optical and infrared counterparts of the Chandra COSMOS-Legacy Survey, a 4.6Ms Chandra program on the 2.2deg^2^ of the COSMOS field, combination of 56 new overlapping observations obtained in Cycle 14 with the previous C-COSMOS survey. In this Paper we report the i, K, and 3.6{mu}m identifications of the 2273 X-ray point sources detected in the new Cycle 14 observations. We use the likelihood ratio technique to derive the association of optical/infrared (IR) counterparts for 97% of the X-ray sources. We also update the information for the 1743 sources detected in C-COSMOS, using new K and 3.6{mu}m information not available when the C-COSMOS analysis was performed. The final catalog contains 4016 X-ray sources, 97% of which have an optical/IR counterpart and a photometric redshift, while ~54% of the sources have a spectroscopic redshift. The full catalog, including spectroscopic and photometric redshifts and optical and X-ray properties described here in detail, is available online. We study several X-ray to optical (X/O) properties: with our large statistics we put better constraints on the X/O flux ratio locus, finding a shift toward faint optical magnitudes in both soft and hard X-ray band. We confirm the existence of a correlation between X/O and the the 2-10keV luminosity for Type 2 sources. We extend to low luminosities the analysis of the correlation between the fraction of obscured AGNs and the hard band luminosity, finding a different behavior between the optically and X-ray classified obscured fraction.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/833/15
- Title:
- CCPC. II. 2<z<6.6 protocluster candidates
- Short Name:
- J/ApJ/833/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Candidate Cluster and Protocluster Catalog (CCPC) is a list of objects at redshifts z>2 composed of galaxies with spectroscopically confirmed redshifts that are coincident on the sky and in redshift. These protoclusters are identified by searching for groups in volumes corresponding to the expected size of the most massive protoclusters at these redshifts. In CCPC1 we identified 43 candidate protoclusters among 14000 galaxies between 2.74<z<3.71. Here we expand our search to more than 40000 galaxies with spectroscopic redshifts z>2.00, resulting in an additional 173 candidate structures. The most significant of these are 36 protoclusters with overdensities {delta}_gal_>7. We also identify three large proto-supercluster candidates containing multiple protoclusters at z=2.3, 3.5 and z=6.56. Eight candidates with N>=10 galaxies are found at redshifts z>4.0. The last system in the catalog is the most distant spectroscopic protocluster candidate known to date at z=6.56.
- ID:
- ivo://CDS.VizieR/J/ApJ/747/102
- Title:
- ^12^C/^13^C ratio for 18 galactic R CrB stars
- Short Name:
- J/ApJ/747/102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observed spectra of R Coronae Borealis (RCB) and hydrogen-deficient carbon (HdC) stars are analyzed by synthesizing the C_2_ Swan bands (1, 0), (0, 0), and (0, 1) using our detailed line list and the Uppsala model atmospheres. The (0, 1) and (0, 0) C_2_ bands are used to derive the ^12^C abundance, and the (1, 0) ^12^C^13^C band to determine the ^12^C/^13^C ratios. The carbon abundance derived from the C_2_ Swan bands is about the same for the adopted models constructed with different carbon abundances over the range 8.5 (C/He=0.1%) to 10.5 (C/He=10%). Carbon abundances derived from C I lines are about a factor of four lower than the carbon abundance of the adopted model atmosphere over the same C/He interval, as reported by Asplund et al., who dubbed the mismatch between adopted and derived C abundance as the "carbon problem." In principle, the carbon abundances obtained from C_2_ Swan bands and that assumed for the model atmosphere can be equated for a particular choice of C/He that varies from star to star. Then, the carbon problem for C_2_ bands is eliminated. However, such C/He ratios are in general less than those of the extreme helium stars, the seemingly natural relatives to the RCB and HdC stars. A more likely solution to the C_2_ carbon problem may lie in a modification of the model atmosphere's temperature structure. The derived carbon abundances and the ^12^C/^13^C ratios are discussed in light of the double degenerate and the final flash scenarios.
- ID:
- ivo://CDS.VizieR/I/303
- Title:
- CdC2000 Bordeaux Carte du Ciel catalogue
- Short Name:
- I/303
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the CdC2000 catalogue issued from the reduction of the complete Bordeaux Carte du Ciel zone observed at the beginning of last century with the Bordeaux astrograph. This catalogue is a positional catalogue of 344780 stars covering the declination zone +11{deg}<delta<+18{deg}. The average epoch of positions is 1914.7. The data are from the 512 Carte du Ciel plates archived at the Bordeaux Observatory and scanned with the APM Cambridge automatic measuring machine. Plates have been individually reduced using the TYCHO-2 Catalogue as astrometric reference. Astrometric standard errors are about 0.10" to 0.12" on positions and 0.6 magnitudes on photographic magnitudes. A detailed study of errors and a comparison of various reduction methods are presented in order to take into account the significant propagated errors from the reference catalogue. The CdC2000 provides positions at the epoch of the plates for 50 682 TYCHO-2 stars. The associated positions are proved to be 0.11" more precise than the positions given by the Tycho-2 catalogue at the epoch of the plates. This work is part of a program of proper motion measurements in the Bordeaux Carte du Ciel zone (PM2000, Cat. <I/300>).
- ID:
- ivo://CDS.VizieR/J/AJ/106/831
- Title:
- cD clusters of galaxies. I.
- Short Name:
- J/AJ/106/831
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the initial results of a spectroscopic study of a sample of cD galaxy clusters. The goal of this program is to study the dynamics of the clusters, with emphasis on determining the nature and frequency of peculiar velocity cD galaxies. In this paper we present redshifts for 611 galaxies in the fields of the rich Abell clusters A193, A399, A401, A1795, A1809, A2063, and A2124. We discuss our data reduction techniques, and compare our derived velocities with previously published values. We find a frequency of emission line galaxies of ~6% in clusters, a factor of 2-3 less than the field.
- ID:
- ivo://CDS.VizieR/J/AJ/116/1529
- Title:
- cD clusters of galaxies. III.
- Short Name:
- J/AJ/116/1529
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the final observational data for a spectroscopic study of a sample of cD galaxy clusters. The goal of this program has been to study the dynamics of the clusters, with emphasis on determining the nature and frequency of peculiar-velocity cD galaxies. In this paper we present redshifts for 762 galaxies in the fields of the rich Abell clusters A779, A1691, A1749, A1767, A1837, A1927, A2067, A2079, A2089, A2199, and A2666. We also present preliminary dynamical properties for these clusters using our measured redshifts.
- ID:
- ivo://CDS.VizieR/J/A+AS/142/353
- Title:
- CDD V photometry of B2 radio galaxies
- Short Name:
- J/A+AS/142/353
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of V-band CCD photometry for 72 low-luminosity radio galaxies from the B2 sample is presented. Most of these galaxies are of early type and their photometric and morphological properties are studied in the paper. We present the resulting surface brightness profiles and isophote parameters' profiles, including ellipticity, position angle, and B4, for 59 galaxies.
- ID:
- ivo://CDS.VizieR/J/AJ/135/1505
- Title:
- CDFs AGNs X-ray power-law photon index
- Short Name:
- J/AJ/135/1505
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a statistical analysis of 173 bright radio-quiet active galactic nuclei (AGNs) selected from the Chandra Deep Field-North and Chandra Deep Field-South surveys (hereafter, CDFs) in the redshift range of 0.1<~<~4. We find that the X-ray power-law photon index ({Gamma}) of radio-quiet AGNs is correlated with their 2-10keV rest-frame X-ray luminosity (LX) at the >99.5% confidence level in two redshift bins: 0.3~<z~<0.96, and 1.5~<z~<3.3 and is slightly less significant in the redshift bin 0.96~<z~<1.5.
- ID:
- ivo://CDS.VizieR/J/ApJS/179/19
- Title:
- CDFS survey: 2 Ms source catalogs
- Short Name:
- J/ApJS/179/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present point-source catalogs for the ~2Ms exposure of the Chandra Deep Field-South (CDF-S) this is one of the two most sensitive X-ray surveys ever performed. The survey covers an area of ~436arcmin^2^ and reaches on-axis sensitivity limits of ~1.9x10^-17^ and ~1.3x10^-16^ergs/cm^2^/s for the 0.5-2.0 and 2-8keV bands, respectively. Four hundred and sixty-two X-ray point sources are detected in at least one of three X-ray bands that were searched; 135 of these sources are new compared to the previous ~1Ms CDF-S detections. Source positions are determined using centroid and matched-filter techniques; the median positional uncertainty is ~0.36". The X-ray-to-optical flux ratios of the newly detected sources indicate a variety of source types; ~55% of them appear to be active galactic nuclei, while ~45% appear to be starburst and normal galaxies. In addition to the main Chandra catalog, we provide a supplementary catalog of 86 X-ray sources in the ~2Ms CDF-S footprint that was created by merging the ~250ks Extended Chandra Deep Field-South with the CDF-S this approach provides additional sensitivity in the outer portions of the CDF-S. A second supplementary catalog that contains 30 X-ray sources was constructed by matching lower significance X-ray sources to bright optical counterparts (R<23.8) the majority of these sources appear to be starburst and normal galaxies. The total number of sources in the main and supplementary catalogs is 578. Optical R-band counterparts and basic optical and infrared photometry are provided for the X-ray sources in the main and supplementary catalogs. We also include existing spectroscopic redshifts for 224 of the X-ray sources.
2240. cD Galaxy in Abell 2107
- ID:
- ivo://CDS.VizieR/J/AJ/104/2078
- Title:
- cD Galaxy in Abell 2107
- Short Name:
- J/AJ/104/2078
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As part of a program to study the kinematics of cD clusters of galaxies, we have measured the radial velocities of 75 galaxies in the field of Abell 2107. Sixty-eight of these galaxies are cluster members. The mean observed velocity of A2105 is 12335 +/- 86 km/s and the velocity dispersion is 672 [+67,-52] km/s. The cD galaxy has a peculiar velocity of 270 km/s with respect to the cluster mean. The distribution of velocities is well fitted by a Gaussian, but the velocities are spatially correlated. We have investigated simple two-body subcluster models for A2107, which are consistent with the observed data and account for the peculiar velocity of the cD galaxy. Alternatively, the spatial distribution of velocities is also consistent with rotation of a single cluster at the 98% confidence level. However, the pure rotation model fails to explain the peculiar velocity of the cD galaxy, which lies at the center of the cluster.
