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2611. Chandra Large-Area Synoptic X-Ray Survey of Lockman Hole-NW
ID:
ivo://nasa.heasarc/clasxs
Title:
Chandra Large-Area Synoptic X-Ray Survey of Lockman Hole-NW
Short Name:
Chan/Syn/LHN
Date:
28 Feb 2025
Publisher:
NASA/GSFC HEASARC
Description:
This table contains the X-ray catalog and basic results from the wide-area, moderately deep Chandra Large Area Synoptic X-ray Survey (CLASXS) of the Lockman Hole-Northwest (LHNW) field (Yang et al. 2004), as well as the results from optical and near-infrared photometric and spectroscopic observations of these X-ray sources (Steffen et al. 2004). The nine ACIS-I fields cover a contiguous solid angle of 0.4 square degrees and reach fluxes of 5 x 10<sup>-16</sup> ergs/cm<sup>2</sup>/s (0.4 - 2 keV) and 3 x 10<sup>-15</sup> ergs/cm<sup>2</sup>/s (2 - 8 keV). (Note that fields LHNW 1-3 were observed during 2001 April 30-May 17, and that the rest of the fields were observed during 2002 April 29-May 4). This survey bridges the gap between ultra-deep pencil-beam surveys, such as the Chandra Deep Fields (CDFs), and shallower, large-area surveys, allowing a better probe of the X-ray sources that contribute most of the 2 - 10 keV cosmic X-ray background (CXB). A total of 525 X-ray point sources and four extended sources were found. There are B, V, R, I, and z' photometry for 521 (99%) of the 525 sources in the X-ray catalog and spectroscopic redshifts for 271 (52%), including 20 stars. The authors did not find evidence for redshift groupings of the X-ray sources, like those found in the Chandra Deep Field surveys, because of the larger solid angle covered by this survey. They separated the X-ray sources by optical spectral type and examined the colors, apparent and absolute magnitudes, and redshift distributions for the broad-line and non-broad-line active galactic nuclei. Combining their wide-area survey with other Chandra and XMM-Newton hard X-ray surveys, they find a definite lack of luminous, high accretion rate sources at z < 1, consistent with previous observations that showed that super-massive black hole growth is dominated at low redshifts by sources with low accretion rates. This table was created by the HEASARC in May 2005 from the merger of 3 CDS tables, corresponding to Tables 2 and 3 from Yang et al. 2005 and Table 1 of Steffen et al. (2005): <p> <pre> J/AJ/128/1501/table2.dat J/AJ/128/1501/table3.dat J/AJ/128/1483/table1.dat </pre> This is a service provided by NASA HEASARC .
2612. ChandraLarge-AreaSynopticX-RaySurveyOptical&IRCatalog
ID:
ivo://nasa.heasarc/clasxsoid
Title:
ChandraLarge-AreaSynopticX-RaySurveyOptical&IRCatalog
Short Name:
CLASXSOID
Date:
28 Feb 2025
Publisher:
NASA/GSFC HEASARC
Description:
This table contains the redshift catalog for the X-ray sources detected in the Chandra Large Area Synoptic X-ray Survey (CLASXS). The catalog for the CLASXS field 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 Deep Field-North (CDF-N) 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. As a result, they probe the X-ray sources that contribute the bulk of the 2-8 keV X-ray background and cover the flux range of the observed break in the log N - log S distribution. This table also contains updated optical and infrared photometric catalogs for the X-ray sources in the CLASXS field. Note that for any source with both CFHT and Subaru data in the R and z' bands, the authors used the CFHT magnitude. Typical photometric uncertainties are given in Section 3.6 of the reference paper (Trouille et al. 2008). The X-ray information for the CLASXS catalog which was published in Yang et al. (2004, AJ, 128, 1501) is available as the HEASARC CLASXS table. This table was created by the HEASARC in January 2009 based on the electronic version of Table 12 from the paper which was obtained from the ApJ web site. This is a service provided by NASA HEASARC .
2613. Chandra large-scale extragalactic jets. I.
ID:
ivo://CDS.VizieR/J/ApJS/197/24
Title:
Chandra large-scale extragalactic jets. I.
Short Name:
J/ApJS/197/24
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this paper, we report the first stages of an investigation into the X-ray properties of extragalactic jets (XJET project). Our approach is to subject all sources for which X-ray emission has been detected by Chandra to uniform reduction procedures. Using Chandra archival data for 106 such sources, we measure X-ray fluxes in three bands and compare these to radio fluxes. We discuss the sample, the reduction methods, and present first results for the ratio of X-ray to radio flux for jet knots and hotspots. In particular, we apply statistical tests to various distributions of key observational parameters to evaluate differences between the different classes of sources.
2614. Chandra Legacy Survey (CLS) Catalog
ID:
ivo://nasa.heasarc/clscat
Title:
Chandra Legacy Survey (CLS) Catalog
Short Name:
CLSCAT
Date:
28 Feb 2025
Publisher:
NASA/GSFC HEASARC
Description:
The COSMOS-Legacy survey is a 4.6-Ms Chandra program that has imaged 2.2 deg<sup>2</sup> of the COSMOS field with an effective exposure of ~160 ks over the central 1.5 deg<sup>2</sup> and of ~80 ks 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. In the reference paper, the authors describe the reduction and analysis of the new observations and the properties of 2273 point sources detected above a spurious probability of 2 x 10<sup>-5</sup>. The authors also present the updated properties of the C-COSMOS sources detected in the new data. The whole survey includes 4,016 point sources (3,814, 2,920 and 2,440 in the full, soft, and hard band). The limiting depths are 2.2 x 10<sup>-16</sup>, 1.5 x 10<sup>-15</sup>, and 8.9 x 10<sup>-16</sup> erg/cm<sup>2</sup>/s in the 0.5-2, 2-10, and 0.5-10 keV bands, respectively. The observed fraction of obscured active galactic nuclei with a column density > 10<sup>22</sup> cm<sup>-2</sup> from the hardness ratio (HR) is ~ 50<sup>+17</sup>_-16_%. Given the large sample, the authors compute source number counts in the hard and soft bands, significantly reducing the uncertainties of 5% - 10%. For the first time, they 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 unprecedented large exposure, the 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. The half-a-field shift tiling strategy was designed to uniformly cover the COSMOS Hubble area in depth and point-spread function (PSF) size by combining the old C-COSMOS (Elvis et al., 2009, ApJS, 184, 158) observations with the new Chandra ones (see Figure 1 in the reference paper). The main properties of the new ACIS-I Chandra COSMOS-Legacy observations are summarized in Table 1 therein. The observations took place in four blocks: 2012 November to 2013 January; 2013 March to July; 2013 October to 2014 January; and 2014 March. The mean net effective exposure time per field was 48.8 ks after all the cleaning and reduction operations. This table was created by the HEASARC in July 2016 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/819/62">CDS Catalog J/ApJ/819/62</a>, file table5.dat. Some of the values for the name parameter in the HEASARC's implementation of this table were corrected in April 2018. This is a service provided by NASA HEASARC .
2615. Chandra LMXB in NGC 1332
ID:
ivo://CDS.VizieR/J/ApJ/612/848
Title:
Chandra LMXB in NGC 1332
Short Name:
J/ApJ/612/848
Date:
21 Oct 2021
Publisher:
CDS
Description:
Chandra ACIS-S3 (Advanced CCD Imaging Spectrometer) observations of the nearby S0 galaxy NGC 1332 resolve much of the X-ray emission into 73 point sources, of which 37 lie within the D_25_ isophote.
2616. Chandra LMXB in NGC 4649
ID:
ivo://CDS.VizieR/J/ApJ/600/729
Title:
Chandra LMXB in NGC 4649
Short Name:
J/ApJ/600/729
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a Chandra X-ray observation of the X-ray bright E2 elliptical galaxy NGC 4649. In addition to bright diffuse emission, we resolve 165 discrete sources, most of which are presumably low-mass X-ray binaries. As found in previous studies, the luminosity function of the resolved sources is well-fitted by a broken power law. In NGC 4697 and NGC 1553, the break luminosity was comparable to the Eddington luminosity of a 1.4M_{sun}_ neutron star.
2617. Chandra LMXB in NGC 4365 and NGC 4382
ID:
ivo://CDS.VizieR/J/ApJ/599/218
Title:
Chandra LMXB in NGC 4365 and NGC 4382
Short Name:
J/ApJ/599/218
Date:
21 Oct 2021
Publisher:
CDS
Description:
We used the Chandra X-Ray Observatory ACIS-S3 to image the X-ray-faint elliptical galaxy NGC 4365 and lenticular galaxy NGC 4382. The observations resolve much of the X-ray emission into 99 and 58 sources, respectively, most of which are low-mass X-ray binaries (LMXBs) associated with each of the galaxies. Within one effective radius of NGC 4365, about 45% of the counts are resolved into sources, 30% are attributed to unresolved LMXBs, and 25% are attributed to diffuse gas. Within two effective radii of NGC 4382, about 22% of the counts are resolved into sources, 33% are attributed to unresolved LMXBs, and 45% are attributed to diffuse gas. We identify 18 out of the 37 X-ray sources in a central field in NGC 4365 with globular clusters.
2618. Chandra Local Volume Survey. I.
ID:
ivo://CDS.VizieR/J/AJ/150/94
Title:
Chandra Local Volume Survey. I.
Short Name:
J/AJ/150/94
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present comprehensive X-ray point source catalogs of NGC55, NGC2403, and NGC4214 as part of the Chandra Local Volume Survey. The combined archival observations have effective exposure times of 56.5ks, 190ks, and 79ks for NGC55, NGC2403, and NGC4214, respectively. When combined with our published catalogs for NGC300 and NGC404, our survey contains 629 X-ray sources total down to a limiting unabsorbed luminosity of ~5x10^35^erg/s in the 0.35-8keV band in each of the five galaxies. We present X-ray hardness ratios, spectral analysis, radial source distributions, and an analysis of the temporal variability for the X-ray sources detected at high significance. To constrain the nature of each X-ray source, we carried out cross-correlations with multi-wavelength data sets. We searched overlapping Hubble Space Telescope observations for optical counterparts to our X-ray detections to provide preliminary classifications for each X-ray source as a likely X-ray binary, background active galactic nucleus, supernova remnant, or foreground star.
2619. Chandra Local Volume Survey: NGC 404 sources
ID:
ivo://CDS.VizieR/J/ApJ/763/128
Title:
Chandra Local Volume Survey: NGC 404 sources
Short Name:
J/ApJ/763/128
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a comprehensive X-ray point-source catalog of NGC 404 obtained as part of the Chandra Local Volume Survey. A new 97ks Chandra ACIS-S observation of NGC 404 was combined with archival observations for a total exposure of ~123ks. Our survey yields 74 highly significant X-ray point sources and is sensitive to a limiting unabsorbed luminosity of ~6x10^35^erg/s in the 0.35-8keV band. To constrain the nature of each X-ray source, cross-correlations with multi-wavelength data were generated. We searched overlapping Hubble Space Telescope observations for optical counterparts to our X-ray detections, but find only two X-ray sources with candidate optical counterparts. We find 21 likely low-mass X-ray binaries (LMXBs), although this number is a lower limit due to the difficulties in separating LMXBs from background active galactic nuclei. The X-ray luminosity functions (XLFs) in both the soft and hard energy bands are presented. The XLFs in the soft band (0.5-2keV) and the hard band (2-8keV) have a limiting luminosity at the 90% completeness limit of 10^35^erg/s and 10^36^erg/s, respectively, significantly lower than previous X-ray studies of NGC 404. We find the XLFs to be consistent with those of other X-ray populations dominated by LMXBs. However, the number of luminous (>10^37^erg/s) X-ray sources per unit stellar mass in NGC 404 is lower than is observed for other galaxies. The relative lack of luminous XRBs may be due to a population of LMXBs with main-sequence companions formed during an epoch of elevated star formation ~0.5Gyr ago.
2620. ChandraLockmanAreaNorthSurvey(CLANS)Optical&IRCatalog
ID:
ivo://nasa.heasarc/clansoid
Title:
ChandraLockmanAreaNorthSurvey(CLANS)Optical&IRCatalog
Short Name:
CLANSOID
Date:
28 Feb 2025
Publisher:
NASA/GSFC HEASARC
Description:
This table contains the redshift catalog for the X-ray sources detected in the Chandra Lockman Area North Survey (CLANS). The redshifts for the CLANS field are all new. For fluxes above 10<sup>-14</sup> ergs cm<sup>-2</sup> s<sup>-1</sup> (2-8 keV) the authors have redshifts for 76% of the sources in the CLANS, CLASXS, and CDF-N surveys. They extend the redshift information for the full sample using photometric redshifts. The goal of the OPTX Project is to use these three surveys, 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 optical and infrared photometric catalog for the CLANS X-ray sources is presented here (see the CLANS Browse table for the X-ray information). The CLANS and CLASXS surveys bridge the gap between the ultra-deep pencil-beam surveys, such as the CDFs, and the shallower, very large-area surveys. As a result, they probe the X-ray sources that contribute the bulk of the 2-8 keV X-ray background and cover the flux range of the observed break in the log N - log S distribution. This table was created by the HEASARC in December 2008 based on the electronic version of Table 11 from the paper which was obtained from the ApJ web site. This is a service provided by NASA HEASARC .

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