- ID:
- ivo://nasa.heasarc/ccosmphotz
- Title:
- Chandra COSMOS (C-COSMOS) Survey Photometric Redshift Catalog
- Short Name:
- CCOSMPHOTZ
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- In their paper, the authors release accurate photometric redshifts for 1692 counterparts to Chandra sources in the central square degree of the Cosmic Evolution Survey (COSMOS) field. The availability of a large training set of spectroscopic redshifts that extends to faint magnitudes enabled photometric redshifts comparable to the highest quality results presently available for normal galaxies. The authors demonstrate that morphologically extended, faint X-ray sources without optical variability are more accurately described by a library of normal galaxies (corrected for emission lines) than by active galactic nucleus (AGN) dominated templates, even if these sources have AGNlike X-ray luminosities. Preselecting the library on the bases of the source properties allowed them to reach an accuracy sigma[Delta-z/(1+Z<sub>spec</sub>)] ~ 0.015 with a fraction of outliers of 5.8% for the entire Chandra-COSMOS sample. In addition, in this study the authors released revised photometric redshifts for the 1735 optical counterparts of the XMM-detected sources over the entire 2 deg<sup>2</sup> of COSMOS (these sources are listed in the HEASARC table XMMCPHOTZ). For 248 sources, their updated photometric redshift differs from the previous release by Delta-z > 0.2. These changes are predominantly due to the inclusion of newly available deep H-band^ photometry (H<sub>AB</sub> = 24 mag). The authors illustrate once again the importance of a spectroscopic training sample and how an assumption about the nature of a source together, with the number and the depth of the available bands, influences the accuracy of the photometric redshifts determined for AGN. These considerations should be kept in mind when defining the observational strategies of upcoming large surveys targeting AGNs, such as eROSITA at X-ray energies and the Australian Square Kilometre Array Pathfinder Evolutionary Map of the Universe in the radio band. This table contains the photometric redshifts and related quantities for 1694 (note that there appears to be 2 more sources than the above-quoted abstract states) Chandra sources in the central square degree of the COSMOS field. Notice that in the original as-published paper no positional information was provided. The HEASARC has assumed that the source numbers used in the present catalog are in the same source numbering scheme as used by Elvis et al. (2009, ApJS, 184, 158, the Chandra COSMOS Survey Point Source Catalog, available at the HEASARC as the CCOSMOSCAT table) and thus obtained the positions and (position-based) names corresponding to these sources. This table was created by the HEASARC in November 2011 based on an electronic version of Table 4 from the reference paper which was obtained from the ApJ website. This is a service provided by NASA HEASARC .
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- ID:
- ivo://nasa.heasarc/ccosmoscat
- Title:
- Chandra COSMOS (C-COSMOS) Survey X-Ray Point Source Catalog
- Short Name:
- CCOSMOSCAT
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Chandra COSMOS Survey (C-COSMOS) is a large, 1.8 Ms, Chandra program that has imaged the central 0.5 deg<sup>2</sup> of the COSMOS field (centered at RA, Dec of 10 hours , +02 degrees) with an effective exposure of ~ 160 ks, and an outer 0.4 deg<sup>2</sup> area with an effective exposure of ~ 80 ks. The limiting source detection depths are 1.9 x 10<sup>-16</sup> erg cm<sup>-2</sup> s<sup>-1</sup> in the soft (0.5 - 2 keV) band, 7.3 x 10<sup>-16</sup> erg cm<sup>-2</sup> s<sup>-1</sup> in the hard (2 - 10 keV) band, and 5.7 x 10<sup>-16</sup> erg cm<sup>-2</sup> s<sup>-1</sup> in the full (0.5 - 10 keV) band. In this paper, the authors describe the strategy, design, and execution of the C-COSMOS survey, and present the catalog of 1761 point sources detected at a probability of being spurious of < 2 x 10<sup>-5</sup> (1655 in the full, 1340 in the soft, and 1017 in the hard bands). By using a grid of 36 heavily (~ 50%) overlapping pointing positions with the ACIS-I imager, a remarkably uniform (+/-12%) exposure across the inner 0.5 deg<sup>2</sup> field was obtained, leading to a sharply defined lower flux limit. The widely different point-spread functions obtained in each exposure at each point in the field required a novel source detection method, because of the overlapping tiling strategy, which is described in a companion paper. This method produced reliable sources down to a 7-12 counts, as verified by the resulting log N-log S curve, with sub-arcsecond positions, enabling optical and infrared identifications of virtually all sources, as reported in a second companion paper. Supporting data products for this table (including images, event files, and exposure maps) are available at the <a href="https://cosmos.astro.caltech.edu/page/xray/">COSMOS Survey website</a> and at <a href="https://irsa.ipac.caltech.edu/data/COSMOS/">IRSA</a>. At the IRSA website, it is also possible to search a database that includes "postage stamps" of the X-ray data for each source, along with the multi-wavelength optical and infrared data, including the I-band, K-band, and Spitzer 3.6-micron (Band 1) images used in the Part III paper (Civano et al. 2012) to identify the sources. See also the related table <a href="ccosmosoid.html">CCOSMOSOID</a> for the optical and infrared identifications of the surveyed X-ray point sources. This table was created by the HEASARC in November 2009 based on an electronic version of the C-COSMOS Catalog which was obtained from the Astrophysical Journal web site. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/ccosrssfag
- Title:
- Chandra COSMOS Radio-Selected Star-Forming Galaxies and AGN Catalog
- Short Name:
- CCOSRSSFAG
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- X-ray surveys contain sizable numbers of star-forming galaxies, beyond the AGN which usually make up the majority of detections. Many methods to separate the two populations are used in the literature, based on X-ray and multi-wavelength properties. The authors aim at a detailed test of the classification schemes and to study the X-ray properties of the resulting samples. They build on a sample of galaxies selected at 1.4 GHz in the VLA-COSMOS survey, classified by Smolcic et al. (2008, ApJS, 177, 14) according to their optical colors and also observed by Chandra. A similarly selected control sample of AGN is also used for comparison. The authors review some X-ray based classification criteria and check how they affect the sample composition. The efficiency of the classification scheme devised by Smolcic et al. (2008) is such that ~30% of composite/misclassified objects are expected because of the higher X-ray brightness of AGN with respect to galaxies. The latter fraction is actually 50% in the X-ray detected sources, while it is expected to be much lower among X-ray undetected sources. Indeed, the analysis of the stacked spectrum of undetected sources shows, consistently, strongly different properties between the AGN and galaxy samples. X-ray based selection criteria are then used to refine both samples. The radio/X-ray luminosity correlation for star-forming (SF) galaxies is found to hold with the same X-ray/radio ratio valid for nearby galaxies. Some evolution of the ratio may be possible for sources at high redshift or high luminosity, though it is likely explained by a bias arising from the radio selection. Finally, in their paper the authors discuss the X-ray number counts of star-forming galaxies from the VLA- and C-COSMOS surveys according to different selection criteria, and compare them to the similar determination from the Chandra Deep Fields. The classification scheme proposed here may find application in future works and surveys. This table contains the catalogs of radio-selected SF- and AGN-candidate sources with an X-ray detection in C-COSMOS which were contained in Tables 2 and 3 of the reference paper, respectively. The HEASARC has merged these into a single table, adding a new parameter sample which is set to 'SFG' for radio-selected SF-candidate sources from Table 2 and to 'AGN' for the AGN-candidate sources from Table 3. This table was created by the HEASARC in June 2012 based on CDS table J/A+A/542/A16 files table2.dat and table3.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/chandfn2ms
- Title:
- Chandra Deep Field North 2-Megasecond Catalog
- Short Name:
- Chan/DF2N
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Chandra Deep Field North (CDFN) 2-Megasecond Catalog contains the point sources found in the ~2 Megasecond (Ms) exposure of the Chandra Deep Field North, currently the deepest X-ray observation of the universe in the 0.5 -8.0 keV band. Five hundred and three (503) X-ray sources were detected over an ~448 square arcminute area in up to seven X-ray bands. Twenty (20) of these X-ray sources lie in the central ~5.3 square arcminute Hubble Deep Field North (13600 (+3800,-3000) sources/deg<sup>2</sup>). The on-axis sensitivity limits are ~2.5x10<sup>-17</sup> ergs/cm<sup>2</sup>/s (0.5 - 2.0 keV) and 1.4x10<sup>-16</sup> ergs/cm<sup>2</sup>/s (2 - 8 keV). Source positions are determined using matched-filter and centroiding techniques; the median positional uncertainty is ~0.3". The X-ray colors of the detected sources indicate a broad variety of source types, although absorbed AGN (including a small number of possible Compton-thick sources) are clearly the dominant type. The average backgrounds in the 0.5 - 2.0 keV and 2 - 8 keV bands are 0.056 and 0.135 counts Ms<sup>-1</sup> pixel<sup>-1</sup>, respectively. The background count distributions are very similar to Poisson distributions. This 2 Ms exposure is approximately photon limited in all seven X-ray bands for regions close to the aim point. This observation does not suffer from source confusion within ~6 arcminutes of the aim point. This table was created by the HEASARC in April 2004 based on CDS catalog table J/AJ/126/539/cdfn.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/chandfn1ms
- Title:
- Chandra Deep Field North 1-Megasecond Catalog
- Short Name:
- ChanDF
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table is the Chandra Deep Field North 1-Megasecond Catalog. It lists point sources detected in an extremely deep X-ray survey (1 Ms) of the Hubble Deep Field North (HDF-N) and its environs (~450 square arcminutes) which has been performed with the Advanced CCD Imaging Spectrometer on board the Chandra X-Ray Observatory. This is one of the two deepest X-ray surveys ever performed; for point sources near the aim point, it reaches 0.5 - 2.0 keV and 2 - 8 keV flux limits of ~3 x 10<sup>-17</sup> and ~2 x 10<sup>-16</sup> ergs cm-2 s-1, respectively. 370 distinct point sources have been detected: 360 in the full (0.5 - 8.0 keV) band, 325 in the soft (0.5 - 2.0 keV) band, 265 in the hard (2 - 8 keV) band, and 145 in the ultrahard (4 - 8 keV) band. Source positions are accurate to within 0.6 - 1.7 arcseconds (at ~90% confidence), depending mainly on the off-axis angle. Source densities of 7100 (+1100, -940) deg<sup>-2</sup> (at 4.2 x 10<sup>-17</sup> ergs cm<sup>-2</sup> s<sup>-1</sup>) and 4200 (+670, -580) deg<sup>-2</sup> (at 3.8 x 10<sup>-16</sup> ergs cm<sup>-2</sup> s<sup>-1</sup>) are observed in the soft and hard bands, respectively. This online catalog was created by the HEASARC in March 2002 based on a machine-readable version of Table 3 of Brandt et al. (2001) that was obtained from the Astronomical Journal website. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/cdfn2msnew
- Title:
- Chandra Deep Field North 2-Megasecond Improved Point Source Catalog
- Short Name:
- CDFN2MSNEW
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the improved point-source catalog for the 2-Ms Chandra Deep Field-North (CDF-N) Survey, implementing a number of recent improvements in Chandra source-cataloguing methodology. For the CDF-N, the main catalog (entries from which are indicated with parameter values of source_sample = "Main" in this HEASARC representation) contains 683 X-ray sources detected with wavdetect at a false-positive probability threshold of 10<sup>-5</sup> that also satisfy a binomial-probability source-selection criterion of P <= 0.004. Such an approach maximizes the number of reliable sources detected: a total of 196 main-catalog sources are new compared to the Alexander et al. (2003, AJ, 126, 539) CDF-N main catalog. The authors also provide a CDF-N supplementary catalog that consist of 72 sources (entries from which are indicated with parameter values of source_sample = "Supp" in this HEASARC representation) detected at the same wavdetect threshold and having P of 0.004-0.1 and K<sub>s</sub> <= 22.9 mag counterparts. For all 755 CDF-N sources, including the 234 newly detected ones (these being generally fainter and more obscured), the authors determine X-ray source positions utilizing centroid and matched-filter techniques; they also provide multi-wavelength identifications, apparent magnitudes of counterparts, spectroscopic and/or photometric redshifts, basic source classifications, and estimates of observed active galactic nucleus and galaxy source densities around respective field centers. Simulations show that the CDF-N main catalog is highly reliable and reasonably complete. Background and sensitivity analyses indicate that the on-axis mean flux limits reached represent a factor of ~1.5-2.0 improvement over the previous CDF-N limit. The 2 Ms CDF-N consists of a total of 20 separate Chandra observations taken between 1999 November 13 and 2002 February 22 with ACIS (see Alexander et al., 2003, AJ, 126, 539 for more details). This table was created by the HEASARC in August 2016 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/224/15">CDS Catalog J/ApJS/224/15</a> files table3.dat (the main source catalog) and table6.dat (the supplementary source catalog). This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/cdfn2msoid
- Title:
- ChandraDeepFieldNorth2-MegasecondOptical&IRCatalog
- Short Name:
- Chan/DF2S
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Chandra Deep Field North (CDFN) 2-Megasecond (2Ms) Optical and IR Catalog is an optical and near-infrared catalog for the X-ray sources in the 2Ms Chandra observation of the Hubble Deep Field North region. It has high-quality multicolor imaging data for all 503 X-ray point sources in the X-ray-selected catalog and reliable spectroscopic redshifts for 284. The authors have spectroscopically identified six high-redshift (z > 1) type II quasars (L<sub>2-8keV</sub> > 10<sup>44</sup> ergs/s) in their sample. The spectroscopic completeness for the R <= 24 sources is 87%. The spectroscopic redshift distribution shows two broad redshift spikes that have clearly grown over those originally seen in the 1Ms exposure. The spectroscopically identified extragalactic sources already comprise 75% of the measured 2-8 keV light. Redshift slices versus 2-8 keV flux show that an impressive 54% of the measured 2-8 keV light arises from sources at z < 1 and 68% from sources at z < 2. The X-ray sample is presented in Alexander et al. (2003, AJ, 126, 539, hereafter ABB2003) and in <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/AJ/126/539">CDS Catalog <J/AJ/126/539></a>, and is also available in the HEASARC Browse system as the CHANDFN2MS table. The optical imaging data consist of Johnson B, Johnson V, Cousins R, Cousins I, and Sloan z' observations obtained with the Subaru prime-focus camera Suprime-Cam on the Subaru 8.2m telescope during February-April of 2001 and 2002. This table was created by the HEASARC in April 2004 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/AJ/126/632/table1a">CDS Catalog J/AJ/126/632/table1a</a>.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/cdfn2msoi2
- Title:
- ChandraDeepFieldNorthUpdatedOptical&IRCatalog
- Short Name:
- CDFN2MSOI2
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the redshift catalog for the X-ray sources detected in the Chandra Deep Field-North (CDF-N). The catalog for the CDF-N includes redshifts from previous work. The authors have extended the redshift information for the full sample using photometric redshifts. The goal of the OPTX Project is to use this survey, together with the Chandra Large-Area Synoptic X-Ray Survey (CLASXS) and the Chandra Lockman Area North Survey (CLANS), which are among the most spectroscopically complete surveys to date, to analyze the effect of spectral type on the shape and evolution of the X-ray luminosity functions and to compare the optical spectral types with the X-ray spectral properties. The CLANS and CLASXS surveys bridge the gap between the ultra-deep pencil-beam surveys, such as the Chandra Deep Fields, and the shallower, very large-area surveys. This table also contains updated optical and infrared photometric data for the X-ray sources in the CDF-N. Typical photometric uncertainties are given in Section 3.6 of the reference paper (Trouille et al. 2008). The X-ray information for the sources detected in the CDF-N 2-megasecond exposure which was published in Alexander et al. (2003, AJ, 126, 539) is available as the HEASARC CHANDFN2MS table, while the earlier catalog which listed information about optical and infrared counterparts (Barger et al. 2003, AJ, 126, 632) is available as the HEASARC CDFN2MSOID table. This table was created by the HEASARC in January 2009 based on the electronic version of Table 13 from the paper which was obtained from the ApJ web site. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/cdfsagncxo
- Title:
- Chandra Deep Field South AGN Spectral Properties Catalog
- Short Name:
- CDFSAGNCXO
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the results of a detailed X-ray spectral analysis of the sources in the 1 Ms catalog of the Chandra Deep Field South (CDFS, Giacconi et al. 2002, <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/139/369">CDS Cat. J/ApJS/139/369</a>, available in Browse as the CHANDFS1MS table), taking advantage of optical spectroscopy and photometric redshifts for 321 extragalactic sources out of the total sample of 347 sources. As a default spectral model, the authors adopt a power law with a slope Gamma with an intrinsic redshifted absorption N<sub>H</sub>, a fixed Galactic absorption and an unresolved Fe emission line. For 82 X-ray bright sources, they are able to perform the X-ray spectral analysis leaving both Gamma and N<sub>H</sub> free. The weighted mean value for the slope of the power law is 1.75 +/- 0.02, and the distribution of best fit values shows an intrinsic dispersion of 0.30. The authors do not find hints of a correlation between the spectral index Gamma and the intrinsic absorption column density N<sub>H</sub>. They then investigate the absorption distribution for the whole sample, deriving the N<sub>H</sub> values in faint sources by fixing Gamma to be 1.8. The authors find that the fraction of absorbed sources (with N<sub>H</sub> > 10<sup>22</sup> cm<sup>-2</sup>) in the sample is constant (at the level of about 75%) or moderately increasing with redshift. Finally, they compare the optical classification to the X-ray spectral properties, confirming that the correspondence of unabsorbed (absorbed) X-ray sources to optical type I (type II) AGN is accurate for at least 80% of the sources with spectral identification (1/3 of the total X-ray sample). This table was created by the HEASARC in August 2007 primarily based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/451/457">CDS Catalog J/A+A/451/457</a> file table1.dat. The positions of the X-ray sources were taken from <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/139/369">CDS Catalog J/ApJS/139/369</a> (Giacconi et al. 2002), except for that of source number 901 which was taken from Table 5 of Szokoly et al. (2004, ApJS, 155, 271). This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/chandfs4ms
- Title:
- Chandra Deep Field South 4-Megasecond Catalog
- Short Name:
- CHANDFS4MS
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the main Chandra source catalog for the 4 megasecond (Ms) Chandra Deep Field-South (CDF-S), which is the deepest Chandra survey to date and covers an area of 464.5 arcmin<sup>2</sup>. It contains 740 X-ray sources that are detected with wavdetect at a false-positive probability threshold of 10<sup>-5</sup> in at least one of three X-ray bands (0.5-8 keV, full band; 0.5-2 keV, soft band; and 2-8 keV, hard band) and also satisfy a binomial-probability source-selection criterion of P < 0.004 (i.e., the probability of sources not being real is less than 0.004); this approach is designed to maximize the number of reliable sources detected. A total of 300 main-catalog sources are new compared to the previous 2 Ms CDF-S main-catalog (the HEASARC CHANDFS2MS table) sources. The authors determined X-ray source positions using centroid and matched-filter techniques and obtained a median positional uncertainty of ~0.42 arcseconds. In their paper, they also provided a supplementary catalog (not included in this HEASARC table), which consists of 36 sources that are detected with wavdetect at a false-positive probability threshold of 10<sup>-5</sup>, satisfy the condition of 0.004 < P < 0.1, and have an optical counterpart with R < 24. Multiwavelength identifications, basic optical/infrared/radio photometry, and spectroscopic/photometric redshifts are provided for the X-ray sources in the main and supplementary catalogs. Seven hundred sixteen (~97%) of the 740 main-catalog sources have multiwavelength counterparts, with 673 (~94% of 716) having either spectroscopic or photometric redshifts. The 740 main-catalog sources span broad ranges of full-band flux and 0.5-8 keV luminosity; the 300 new main-catalog sources span similar ranges although they tend to be systematically lower. Basic analyses of the X-ray and multiwavelength properties of the sources indicate that >75% of the main-catalog sources are active galactic nuclei (AGNs); of the 300 new main-catalog sources, about 35% are likely normal and starburst galaxies, reflecting the rise of normal and starburst galaxies at the very faint flux levels uniquely accessible to the 4 Ms CDF-S. Near the center of the 4 Ms CDF-S (i.e., within an off-axis angle of 3'), the observed AGN and galaxy source densities have reached 9800 (+1300,-1100) deg<sup>-2</sup> and 6900 (+1100,-900) deg<sup>-2</sup>, respectively. Simulations show that the main catalog is highly reliable and is reasonably complete. The mean backgrounds (corrected for vignetting and exposure-time variations) are 0.063 and 0.178 counts Ms<sup>-1</sup> pixel<sup>-1</sup> (for a pixel size of 0.492 arcseconds) for the soft and hard bands, respectively; the majority of the pixels have zero background counts. The 4 Ms CDF-S reaches on-axis flux limits of ~3.2 x 10<sup>-17</sup>, 9.1 x 10<sup>-18</sup>, and 5.5 x 10<sup>-17</sup> erg cm<sup>-2</sup> s<sup>-1</sup> for the full, soft, and hard bands, respectively. An increase in the CDF-S exposure time by a factor of ~2-2.5 would provide further significant gains and probe key unexplored discovery space. This HEASARC table comprises Table 3 from the reference paper, the Main Chandra Source Catalog of 740 X-ray sources. The 36 optically bright Chandra sources that were listed in Table 6 of the reference paper are thus not included herein. This table was created by the HEASARC in July 2011 based on an electronic version of Table 3 from the reference paper which was obtained from the ApJS web site. This is a service provided by NASA HEASARC .
