- ID:
- ivo://CDS.VizieR/J/ApJS/201/30
- Title:
- The Chandra COSMOS survey. III.
- Short Name:
- J/ApJS/201/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Chandra COSMOS Survey (C-COSMOS) is a large, 1.8Ms, Chandra program that has imaged the central 0.9deg^2^ of the COSMOS field down to limiting depths of 1.9x10^-16^erg/cm^2^/s in the soft (0.5-2keV) band, 7.3x10^-16^erg/cm^2^/s in the hard (2-10keV) band, and 5.7x10^-16^erg/cm^2^/s in the full (0.5-10keV) band. In this paper we report the i, K, and 3.6um identifications of the 1761 X-ray point sources. We use the likelihood ratio technique to derive the association of optical/infrared counterparts for 97% of the X-ray sources. For most of the remaining 3%, the presence of multiple counterparts or the faintness of the possible counterpart prevented a unique association. For only 10 X-ray sources we were not able to associate a counterpart, mostly due to the presence of a very bright field source close by. Only two sources are truly empty fields. The full catalog, including spectroscopic and photometric redshifts and classification described here in detail, is available online.
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- ID:
- ivo://CDS.VizieR/J/AJ/126/539
- Title:
- The Chandra Deep Fields North and South
- Short Name:
- J/AJ/126/539
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present point-source catalogs for the ~2Ms exposure of the Chandra Deep Field North, currently the deepest X-ray observation of the universe in the 0.5-8.0keV band. Five hundred and three (503) X-ray sources are detected over an ~448arcmin^2^ area in up to seven X-ray bands. Twenty (20) of these X-ray sources lie in the central 5.3 arcmin^2^ Hubble Deep Field North (13600^+3800^_-3000_sources/deg^2^). The on-axis sensitivity limits are 2.5x10^-17^ergs/cm^2^/s (0.5-2.0keV) and 1.4x10^-16^ergs/cm^2^/s (2-8keV). Source positions are determined using matched-filter and centroiding techniques; the median positional uncertainty is ~0.3". To allow consistent comparisons, the point-source catalogs for the 1Ms Chandra Deep Field South (CDF-S; see Cat. J/ApJS/139/369) have also been produced. Three hundred and twenty-six (326) X-ray sources are included in the main Chandra South catalog, and an additional 42 optically bright X-ray sources are included in a lower significance Chandra catalog. We find good agreement with the photometry of the previously published CDF-S catalogs; however, we provide significantly improved positional accuracy.
- ID:
- ivo://CDS.VizieR/IX/57
- Title:
- The Chandra Source Catalog (CSC), Release 2.0
- Short Name:
- IX/57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Chandra Source Catalog (CSC) is the definitive catalog of X-ray sources detected by the Chandra X-ray Observatory. By combining Chandra's sub-arcsecond on-axis spatial resolution and low instrumental background with consistent data processing, the CSC delivers a wide variety of uniformly calibrated properties and science ready data products for detected sources over four decades of flux. The second major release of the catalog, CSC 2.0, includes measured properties for 317,167 unique compact and extended X-ray sources in the sky, allowing statistical analysis of large samples, as well as individual source studies. The sensitivity limit for compact sources in CSC 2.0 is ~5 net counts (a factor of >~2 better than the previous catalog release). This improvement is achieved by using a two-stage approach that involves co-adding multiple observations of the same field prior to source detection, and then using an optimized source detection method.
- ID:
- ivo://CDS.VizieR/IX/45
- Title:
- The Chandra Source Catalog, Release 1.1
- Short Name:
- IX/45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Chandra Source Catalog (CSC) is a general purpose virtual X-ray astrophysics facility that provides access to a carefully selected set of generally useful quantities for individual X-ray sources, and is designed to satisfy the needs of a broad-based group of scientists, including those who may be less familiar with astronomical data analysis in the X-ray regime. The first release of the CSC includes information about 94,676 distinct X-ray sources detected in a subset of public Advanced CCD Imaging Spectrometer imaging observations from roughly the first eight years of the Chandra mission. This release of the catalog includes point and compact sources with observed spatial extents <~30''. The catalog (1) provides access to the best estimates of the X-ray source properties for detected sources, with good scientific fidelity, and directly supports scientific analysis using the individual source data; (2) facilitates analysis of a wide range of statistical properties for classes of X-ray sources; and (3) provides efficient access to calibrated observational data and ancillary data products for individual X-ray sources, so that users can perform detailed further analysis using existing tools. The catalog includes real X-ray sources detected with flux estimates that are at least 3 times their estimated 1-{sigma} uncertainties in at least one energy band, while maintaining the number of spurious sources at a level of <~1 false source per field for a 100ks observation. For each detected source, the CSC provides commonly tabulated quantities, including source position, extent, multi-band fluxes, hardness ratios, and variability statistics, derived from the observations in which the source is detected. In addition to these traditional catalog elements, for each X-ray source the CSC includes an extensive set of file-based data products that can be manipulated interactively, including source images, event lists, light curves, and spectra from each observation in which a source is detected.
- ID:
- ivo://CDS.VizieR/J/ApJS/236/48
- Title:
- The Chandra UDS survey (X-UDS)
- Short Name:
- J/ApJS/236/48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the X-UDS survey, a set of wide and deep Chandra observations of the Subaru-XMM Deep/UKIDSS Ultra Deep Survey (SXDS/UDS) field. The survey consists of 25 observations that cover a total area of 0.33deg^2^. The observations are combined to provide a nominal depth of ~600ks in the central 100arcmin^2^ region of the field that has been imaged with Hubble/WFC3 by the CANDELS survey and ~200ks in the remainder of the field. In this paper, we outline the survey's scientific goals, describe our observing strategy, and detail our data reduction and point source detection algorithms. Our analysis has resulted in a total of 868 band-merged point sources detected with a false-positive Poisson probability of <1x10^-4^. In addition, we present the results of an X-ray spectral analysis and provide best-fitting neutral hydrogen column densities, N_H_, as well as a sample of 51 Compton-thick active galactic nucleus candidates. Using this sample, we find the intrinsic Compton-thick fraction to be 30%-35% over a wide range in redshift (z=0.1-3), suggesting the obscured fraction does not evolve very strongly with epoch. However, if we assume that the Compton-thick fraction is dependent on luminosity, as is seen for Compton-thin sources, then our results are consistent with a rise in the obscured fraction out to z~3. Finally, an examination of the host morphologies of our Compton-thick candidates shows a high fraction of morphological disturbances, in agreement with our previous results.
- ID:
- ivo://CDS.VizieR/J/ApJS/224/24
- Title:
- The COSMOS2015 catalog
- Short Name:
- J/ApJS/224/24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the COSMOS2015 catalog, which contains precise photometric redshifts and stellar masses for more than half a million objects over the 2deg^2^ COSMOS field. Including new YJHKs images from the UltraVISTA-DR2 survey, Y-band images from Subaru/Hyper-Suprime-Cam, and infrared data from the Spitzer Large Area Survey with the Hyper-Suprime-Cam (SPLASH) Spitzer legacy program, this near-infrared-selected catalog is highly optimized for the study of galaxy evolution and environments in the early universe. To maximize catalog completeness for bluer objects and at higher redshifts, objects have been detected on a {chi}^2^ sum of the YJHKs and z^++^ images. The catalog contains ~6x10^5^ objects in the 1.5deg^2^ UltraVISTA-DR2 region and ~1.5x10^5^ objects are detected in the "ultra-deep stripes" (0.62deg^2^) at Ks<=24.7 (3{sigma}, 3", AB (AB) magnitude). Through a comparison with the zCOSMOS-bright spectroscopic redshifts, we measure a photometric redshift precision of {sigma}_{Delta}z/(1+zs)_=0.007 and a catastrophic failure fraction of {eta}=0.5%. At 3<z<6 , using the unique database of spectroscopic redshifts in COSMOS, we find {sigma}_{Delta}z/(1+zs)_=0.021 and {eta}=13.2% . The deepest regions reach a 90% completeness limit of 10^10^M_{sun}_ to z=4. Detailed comparisons of the color distributions, number counts, and clustering show excellent agreement with the literature in the same mass ranges. COSMOS2015 represents a unique, publicly available, valuable resource with which to investigate the evolution of galaxies within their environment back to the earliest stages of the history of the universe.
- ID:
- ivo://CDS.VizieR/J/ApJ/819/62
- Title:
- The COSMOS-Legacy Survey (CLS) catalog
- Short Name:
- J/ApJ/819/62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The COSMOS-Legacy survey is a 4.6Ms Chandra program that has imaged 2.2deg^2^ of the COSMOS field with an effective exposure of ~160ks over the central 1.5deg^2^ and of ~80ks in the remaining area. The survey is the combination of 56 new observations obtained as an X-ray Visionary Project with the previous C-COSMOS survey. We describe the reduction and analysis of the new observations and the properties of 2273 point sources detected above a spurious probability of 2x10^-5^. We also present the updated properties of the C-COSMOS sources detected in the new data. The whole survey includes 4016 point sources (3814, 2920 and 2440 in the full, soft, and hard band). The limiting depths are 2.2x10^-16^, 1.5x10^-15^, and 8.9x10^-16^erg/cm^2^/s in the 0.5-2, 2-10, and 0.5-10keV bands, respectively. The observed fraction of obscured active galactic nuclei with a column density >10^22^/cm^2^ from the hardness ratio (HR) is ~50^+17^_-16_%. Given the large sample we compute source number counts in the hard and soft bands, significantly reducing the uncertainties of 5%-10%. For the first time we compute number counts for obscured (HR>-0.2) and unobscured (HR<-0.2) sources and find significant differences between the two populations in the soft band. Due to the unprecedent large exposure, COSMOS-Legacy area is three times larger than surveys at similar depths and its depth is three times fainter than surveys covering similar areas. The area-flux region occupied by COSMOS-Legacy is likely to remain unsurpassed for years to come.
- ID:
- ivo://CDS.VizieR/J/ApJS/172/561
- Title:
- The 400d cluster Survey
- Short Name:
- J/ApJS/172/561
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of galaxy clusters detected in a new ROSAT PSPC survey. The survey is optimized to sample, at high redshifts, the mass range corresponding to T>5keV clusters at z=0. Technically, our survey is the extension of the 160 square degree survey (160d, Cat. J/ApJ/502/558). We use the same detection algorithm, thus preserving high quality of the resulting sample; the main difference is a significant increase in sky coverage. The new survey covers 397deg^2^ and is based on 1610 high Galactic latitude ROSAT PSPC pointings, virtually all pointed ROSAT data suitable for the detection of distant clusters. The search volume for X-ray luminous clusters within z<1 exceeds that of the entire local universe (z<0.1). We detected 287 extended X-ray sources with fluxes f>1.4x10^-13^ergs/s/cm^2^ in the 0.5-2keV energy band, of which 266 (93%) are optically confirmed as galaxy clusters, groups or individual elliptical galaxies.
989. The 2E Catalogue
- ID:
- ivo://CDS.VizieR/IX/13
- Title:
- The 2E Catalogue
- Short Name:
- IX/13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog contains sources from EINSTEIN IPC (Imaging Proportional counter aboard the EINSTEIN (HEAO 2) satellite, in orbit between November 1978 and April 1981) detected during pointed observations. Note that a single source may have more than one entry in the catalog.
- ID:
- ivo://CDS.VizieR/IX/24
- Title:
- The Einstein Observatory HRI Source List
- Short Name:
- IX/24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Einstein Observatory is the second of NASA's three High Energy Astrophysical Observatories, HEAO-2, renamed Einstein after launch, and was the first fully imaging X-ray telescope put into space. It observed in the energy range 0.2-20keV. It was launched on 12 November 1978, and remained in operation until April 1981. The High Resolution Imager (HRI) is one fo the four instruments aboard the Einstein Observatory, operating in the 0.2-3.0keV energy range, with a spatial resolution of a few arcseconds, and a field of view of 25arcmin. Field and source parameters observed with this instrument are given here.