- ID:
- ivo://CDS.VizieR/J/A+A/462/449
- Title:
- Chandra point-source counts in galaxy cluster
- Short Name:
- J/A+A/462/449
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With the superb angular resolution of the Chandra Observatory, it is now possible to detect X-ray point sources, either embedded in galaxy clusters or along the cluster line of sight, which could not be resolved by previous instruments. This now allows studies of source counts in distant cluster fields. We want to analyze the inner region of clusters of galaxies to check for the presence of any over-density of X-ray point sources embedded in the gas diffuse emission. These point sources are possible AGN belonging to the clusters and could contaminate the cluster emission. We used a sample of 18 distant (0.25<z<1.01) galaxy clusters from the Chandra archive to construct the logN-logS, in both the soft and hard energy bands, for the X-ray point sources detected in the central cluster region to be compared with the counts of point sources detected in similarly deep fields without clusters.
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- ID:
- ivo://nasa.heasarc/gcptsrccxo
- Title:
- Chandra Point Sources in 18 Distant Galaxy Clusters
- Short Name:
- GCPTSRCCXO
- Date:
- 02 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- With the superb angular resolution of the Chandra Observatory, it is now possible to detect X-ray point sources, either embedded in galaxy clusters or along the cluster line of sight, which could not be resolved by previous instruments. This now allows studies of source counts in distant cluster fields. The authors want to analyze the inner region of clusters of galaxies to check for the presence of any over-density of X-ray point sources embedded in the gas diffuse emission. These point sources are possible AGN belonging to the clusters and could contaminate the cluster emission. The authors used a sample of 18 distant (0.25 < z < 1.01) galaxy clusters from the Chandra archive to construct the log N - log S relation, in both the soft and hard energy bands, for the X-ray point sources detected in the central cluster region to be compared with the counts of point sources detected in similarly deep fields without clusters. The authors find a ~2-sigma excess of cluster region sources at the bright end of the log N - log S distribution. The radial distribution of the brightest X-ray point sources confirms this excess and indicates that it is confined to the inner 0.5 Mpc of the cluster region. The results suggest the possible existence of X-ray sources belonging to the cluster (most probably AGN, given their 0.5-10 keV luminosity ranging from 10<sup>43</sup> to 10<sup>44</sup> erg s<sup>-1</sup>): on average one every three clusters. Unlike previous studies, which have mainly investigated the point-source population in the vicinity of the galaxy clusters, the present study analyzes the content of point sources within the 1 Mpc region covered by the cluster extent. This work confirms the findings of other investigators who analyzed the central 1 Mpc region of more massive clusters and/or groups in a similar redshift range. The X-ray source excess found here is much smaller than the excess of radio galaxies found recently in high-z X-ray selected clusters, possibly due to the better sensitivity of the radio observations. The properties of the clusters and of the Chandra exposures in which they were observed are given in Table 1 of the reference paper, and are reproduced below: <pre> Cluster Name z RA (J2000) Dec ObsID ACIS Mode Exp N_H L_sb L_hb h m s d ' " ks [units are below] Abell 2125 0.246 15 41 12 +66 16 01 2207 I VF 79.7 2.77 0.13 0.56 ZW CL 1454.8+2233 0.258 14 57 15 +22 20 33 4192 I VF 91.4 3.22 0.23 0.74 MS 1008.1-1224 0.302 10 10 32 -12 39 23 926 I VF 44.2 6.74 0.44 1.57 ZW CL 0024.0+1652 0.394 00 26 35 +17 09 39 929 S VF 36.7 4.19 0.34 2.22 MS 1621.5+2640 0.426 16 23 36 +26 34 21 546 I F 30.0 3.59 0.81 3.41 RXJ 1701.3+6414 0.453 17 01 24 +64 14 10 547 I VF 49.5 2.59 0.64 2.67 CL 1641+4001 0.464 16 41 53 +40 01 46 3575 I VF 44.0 1.02 0.67 2.62 V 1524.6+0957 0.516 15 24 40 +09 57 48 1664 I VF 49.9 2.92 0.89 3.29 MS 0451.6-0305 0.539 04 54 12 -03 00 53 902 S F 41.5 5.18 0.73 4.12 V 1121+2327 0.562 11 20 57 +23 26 27 1660 I VF 66.9 1.30 0.73 3.00 MS 2053.7-0449 0.583 20 56 21 -04 37 51 1667 I VF 43.5 4.96 1.32 4.91 V 1221+4918 0.700 12 21 26 +49 18 30 1662 I VF 79.4 1.44 1.18 4.62 MS 1137.5+6625 0.782 11 40 22 +66 08 18 536 I VF 117.5 1.18 0.81 4.04 RDCSJ 1317+2911 0.805 13 17 21 +29 11 19 2228 I VF 111.3 1.04 0.85 3.59 RDCSJ 1350+6007 0.805 13 50 48 +60 06 54 2229 I VF 58.3 1.76 1.77 7.26 RXJ 1716.4+6708 0.813 17 16 49 +67 08 26 548 I F 51.5 3.71 2.17 9.45 MS 1054.4-0321 0.830 10 56 59 -03 37 37 512 S F 67.5 3.67 1.07 6.61 WARPJ 1415.1+3612 1.013 14 15 11 +36 12 00 4163 I VF 89.2 1.10 1.93 7.54 </pre> where Exp is the Chandra exposure time in ks corresponding to the nominal exposure filtered to exclude time periods of high background, N_H is the Galactic hydrogen column density in the direction of the cluster of galaxies, in units of 10<sup>20</sup> cm<sup>-2</sup>, and L_sb and L_hb are the limiting luminosities in units of 10<sup>42</sup> erg s<sup>-1</sup> for point sources in the clusters in the 0.5-2.0 keV and 2-10 keV energy bands, respectively. This table was created by the HEASARC in September 2010 based on the electronic version of Table 2 from the reference paper which was obtained from the CDS, their catalog J/A+A/462/449. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/chansexsi
- Title:
- Chandra Serendipitous Extragalactic X-Ray Source ID (SEXSI) Catalog
- Short Name:
- Chan/Seren/ID
- Date:
- 02 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Serendipitous Extragalactic X-Ray Source Identification (SEXSI) program is designed to extend greatly the sample of identified extragalactic hard X-ray (2 - 10 keV) sources at intermediate fluxes (~10<sup>-13</sup> to 10<sup>-15</sup> erg/cm<sup>2</sup>/s). SEXSI, which studies sources selected from more than 2 deg<sup>2</sup>, provides an essential complement to the Chandra Deep Fields, which reach depths of 5 x 10<sup>-16</sup> erg/cm<sup>2</sup>/s (2 - 10 keV) but over a total area of less than 0.2 deg<sup>2</sup>. In their published paper, the authors describe the characteristics of the survey and their X-ray data analysis methodology. They present the cumulative flux distribution for the X-ray sample of 1034 hard sources and discuss the distribution of spectral hardness ratios. Their log N -log S in this intermediate flux range connects to those found in the Deep Fields, and by combining the data sets, they constrain the hard X-ray population over the flux range in which the differential number counts change slope and from which the bulk of the 2 - 10 keV X-ray background arises. They further investigate the log N - log S distribution separately for soft and hard sources in the sample, finding that while a clear change in slope is seen for the softer sample, the hardest sources are well described by a single power law down to the faintest fluxes, consistent with the notion that they lie at lower average redshift. In the SEXSI program, fields were selected with high Galactic latitude (|b| > 20 degrees) and with declinations accessible to the optical facilities available to the authors (declination > -20 degrees). They used observations taken with Chandra's Advanced Camera for Imaging Spectroscopy (ACIS I- and S-modes; Bautz et al., 1998, Proc. SPIE, 3444, 210) only (for sensitivity in the hard band). All the fields presented in this paper have data that are available in the Chandra public archive. This table was created by the HEASARC in June 2004 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/596/944/table4">CDS Catalog J/ApJ/596/944/table4</a>.dat which is a representation of Table 4 from the published version. Note that it does not include the Soft-Band-Only Source Catalog (Table 6 in the published version of the paper). This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/chansexoid
- Title:
- Chandra Serendipitous Extragalactic X-Ray Source ID (SEXSI) Optical Follow-Up
- Short Name:
- Chan/Seren/Opt
- Date:
- 02 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Serendipitous Extragalactic X-ray Source Identification (SEXSI) Program is designed to expand significantly the sample of identified extragalactic hard X-ray sources at intermediate fluxes, 10<sup>-15</sup> ergs/cm<sup>2</sup>/s < 2-10 keV Flux <~ 10<sup>-13</sup> ergs/cm<sup>2</sup>/s. SEXSI, which includes sources derived from more than 2 square degrees of Chandra images, provides the largest hard X-ray-selected sample yet studied, offering an essential complement to the Chandra Deep Fields (total area of 0.2 square degrees). In Eckart et al. (2005, Paper II) R-band optical imaging of the SEXSI fields from the Palomar P60 and P200, the MDM 2.4m and 1.3m, and the Keck I telescopes is described. The authors have identified counterparts or derived flux limits for nearly 1000 hard X-ray sources. Using the optical images, they have derived accurate source positions. They have investigated correlations between optical and X-ray flux, and optical flux and X-ray hardness ratio. They have also studied the density of optical sources surrounding X-ray counterparts, as well as the properties of optically faint, hard X-ray sources. In Eckart et al. (2006, Paper III) optical spectra of 477 counterparts are presented. These spectra reach to R-band magnitudes of <~24 and have produced identifications and redshifts for 438 hard X-ray sources. Typical completeness levels in the 27 Chandra fields studied are 40-70%. The vast majority of the 2-10 keV selected sample are AGNs with redshifts between 0.1 and 3; the highest redshift source lies at z = 4.33. This table which combines data presented in Eckart et al. (2005, 2006) has links to the list of SEXSI X-ray sources (the HEASARC Browse table CHANSEXSI: see Paper I = Harrison et al. 2003, ApJ, 596, 944). This table was originally created by the HEASARC in June 2005 based on the CDS version of Table 3 from Eckart et al. (2005: CDS table J/ApJS/156/35/table3.dat). It was updated in August 2006 to include information from Table 2 of Eckart et al. (2006: the electronic version available at the electronic ApJ web site). This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/chansexagn
- Title:
- Chandra Serendipitous Extragalactic X-Ray Source ID (SEXSI)/Spitzer AGN Catalog
- Short Name:
- CHANSEXAGN
- Date:
- 02 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The authors compare the relative merits of active galactic nuclei (AGN) selection at X-ray and mid-infrared wavelengths using data from moderately deep fields observed by both Chandra and Spitzer. The X-ray-selected AGN sample and associated photometric and spectroscopic optical follow-up are drawn from a subset of fields studied as part of the Serendipitous Extragalactic X-ray Source Identification (SEXSI) program. Mid-infrared data in these fields are derived from targeted and archival Spitzer imaging, and mid-infrared AGN selection is accomplished primarily through application of the Infrared Array Camera (IRAC) color-color AGN "wedge" selection technique. Nearly all X-ray sources in these fields which exhibit clear spectroscopic signatures of AGN activity have mid-infrared colors consistent with IRAC AGN selection. These are predominantly the most luminous X-ray sources. X-ray sources that lack high-ionization and/or broad lines in their optical spectra are far less likely to be selected as AGNs by mid-infrared color selection techniques. The fraction of X-ray sources identified as AGN in the mid-infrared increases monotonically as the X-ray luminosity increases. Conversely, only 22% of mid-infrared-selected AGN are detected at X-ray energies in the moderately deep (t_exp_n~ 100 ks) SEXSI Chandra data. The authors have expanded the multi-wavelength data available for six SEXSI fields by obtaining Spitzer imaging observations. All six fields have deep Chandra X-ray images, optical imaging, and extensive, deep optical spectroscopy -- all of which has been published in Harrison et al. (2003, ApJ, 596, 944), Eckart et al. (2005, ApJS, 156, 35), and Eckart et al. (2006, ApJS, 165, 19). The authors obtained mid-infrared imaging through both archival and targeted Spitzer programs which include imaging at 3.6, 4.5, 5.8, and 8 micron (µm) from IRAC (PID 00017, 00064, 20694 and 20808), and imaging at 24 um from MIPS (PID 20808 and 00083). This table contains mid-IR photometric data for 290 hard X-ray-selected SEXSI sources. Each of the four IRAC catalogs as well as the MIPS catalog was individually matched to the SEXSI X-ray source positions using a 2.5 arcseconds search radius. To calculate a false match rate, the authors shifted the X-ray source catalog by 1' and matched to the IRAC and MIPS catalogs; this entire procedure was repeated 6 times using different 1' shifts. The resulting false match rates were 10.1% (3.6 um), 7.2% (4.5 um), 3.7% (5.8 um), 2.6% (8.0 um), 1% (24 um), and <1% for four-band-detected IRAC sources. This table was created by the HEASARC in Match 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/708/584">CDS Catalog J/ApJ/708/584</a> file table2.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/MNRAS/383/330
- Title:
- Chandra Small Magellanic Cloud Wing Survey
- Short Name:
- J/MNRAS/383/330
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have detected 523 sources in a survey of the Small Magellanic Cloud (SMC) Wing with Chandra. By cross-correlating the X-ray data with optical and near-infrared catalogues, we have found 300 matches. Using a technique that combines X-ray colours and X-ray to optical flux ratios, we have been able to assign preliminary classifications to 265 of the objects. Our identifications include four pulsars, one high-mass X-ray binary (HMXB) candidate, 34 stars and 185 active galactic nuclei (AGN). In addition, we have classified 32 sources as hard AGN which are likely absorbed by local gas and dust, and nine soft AGN whose nature is still unclear. Considering the abundance of HMXBs discovered so far in the Bar of the SMC the number that we have detected in the Wing is low.
- ID:
- ivo://CDS.VizieR/J/ApJ/716/1217
- Title:
- Chandra SMC deep field sources
- Short Name:
- J/ApJ/716/1217
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a pair of 100ks Chandra observations in the Small Magellanic Cloud (SMC) to survey high-mass X-ray binaries (HMXBs), stars, and low-mass X-ray binaries (LMXBs)/cataclysmic variables down to L_x_=4.3x10^32^erg/s. The two SMC Deep Fields (DFs) are located in the most active star-forming region of the bar, with Deep Field-1 positioned at the most pulsar-rich location identified from previous surveys. Two new pulsars were discovered in the outburst: CXOU J004929.7-731058 (P=892s), CXOU J005252.2-721715 (P=326s), and three new HMXB candidates were identified. Of the 15 Be-pulsars now known in the field, 13 were detected, with pulsations seen in 9 of them. Bright optical counterparts exist for 40 of the X-ray sources, of which 33 are consistent with early-type stars (M_V_<-2, B-V<0.2), and are the subject of a companion paper. The results point to an underlying HMXB population density up to double that of active systems. The full catalog of 394 point sources is presented along with detailed analyses of timing and spectral properties.
3508. Chandra Source Catalog
- ID:
- ivo://cxc.harvard.edu/csc
- Title:
- Chandra Source Catalog
- Short Name:
- CSC
- Date:
- 24 Oct 2019
- Publisher:
- Chandra X-ray Observatory
- Description:
- The Chandra X-ray Observatory is the U.S. follow-on to the Einstein Observatory and one of NASA"s Great Observatories. Chandra was formerly known as AXAF, the Advanced X-ray Astrophysics Facility, but renamed by NASA in December, 1998. Originally three instruments and a high-resolution mirror carried in one spacecraft, the project was reworked in 1992 and 1993. The Chandra spacecraft carries a high resolution mirror, two imaging detectors, and two sets of transmission gratings. Important Chandra features are: an order of magnitude improvement in spatial resolution, good sensitivity from 0.1 to 10 keV, and the capability for high spectral resolution observations over most of this range. The Chandra Source Catalog (CSC) includes information about X-ray sources detected in observations obtained using the Chandra X-ray Observatory. Release 2.0 of the catalog includes 317,167 point, compact, and extended sources detected in ACIS and HRC-I imaging observations released publicly prior to the end of 2014. Observed source positions and multi-band count rates are reported, as well as numerous derived spatial, photometric, spectral, and temporal calibrated source properties that may be compared with data obtained by other telescopes. Each record includes the best estimates of the properties of a source based on data extracted from all observations in which the source was detected. The Chandra Source Catalog is extracted from the CXC"s Chandra Data Archive (CDA). The CXC should be acknowledged as the source of Chandra data. For detailed information on the Chandra Observatory and datasets see: http://cxc.harvard.edu/ for general Chandra information; http://cxc.harvard.edu/cda/ for the Chandra Data Archive; http://cxc.harvard.edu/csc/ for Chandra Source Catalog information.
3509. Chandra Source Catalog
- ID:
- ivo://cxc.harvard.edu/csc.siap
- Title:
- Chandra Source Catalog
- Short Name:
- CSC
- Date:
- 24 Oct 2019
- Publisher:
- Chandra X-ray Observatory
- Description:
- The Chandra X-ray Observatory is the U.S. follow-on to the Einstein Observatory. Chandra was formerly known as AXAF, the Advanced X-ray Astrophysics Facility, but renamed by NASA in December, 1998. Originally three instruments and a high-resolution mirror carried in one spacecraft, the project was reworked in 1992 and 1993. The Chandra spacecraft carries a high resolution mirror, two imaging detectors, and two sets of transmission gratings. Important Chandra features are: an order of magnitude improvement in spatial resolution, good sensitivity from 0.1 to 10 keV, and the capability for high spectral resolution observations over most of this range. The Chandra Source Catalog (CSC) includes information about X-ray sources detected in observations obtained using the Chandra X-ray Observatory. Release 2.0 of the catalog includes 317,167 point, compact, and extended sources detected in ACIS and HRC-I imaging observations released publicly prior to the end of 2014. Observed source positions and multi-band count rates are reported, as well as numerous derived spatial, photometric, spectral, and temporal calibrated source properties that may be compared with data obtained by other telescopes. Each record includes the best estimates of the properties of a source based on data extracted from all observations in which the source was detected. The Chandra Source Catalog is extracted from the CXC"s Chandra Data Archive (CDA). The CXC should be acknowledged as the source of Chandra data. For detailed information on the Chandra Observatory and datasets see: http://cxc.harvard.edu/ for general Chandra information; http://cxc.harvard.edu/cda/ for the Chandra Data Archive; http://cxc.harvard.edu/csc/ for Chandra Source Catalog information.
- ID:
- ivo://cxc.harvard.edu/cscr2.siap
- Title:
- Chandra Source Catalog Release 2
- Short Name:
- CSCR2
- Date:
- 24 Oct 2019
- Publisher:
- Chandra X-ray Observatory
- Description:
- The Chandra X-ray Observatory is the U.S. follow-on to the Einstein Observatory. Chandra was formerly known as AXAF, the Advanced X-ray Astrophysics Facility, but renamed by NASA in December, 1998. Originally three instruments and a high-resolution mirror carried in one spacecraft, the project was reworked in 1992 and 1993. The Chandra spacecraft carries a high resolution mirror, two imaging detectors, and two sets of transmission gratings. Important Chandra features are: an order of magnitude improvement in spatial resolution, good sensitivity from 0.1 to 10 keV, and the capability for high spectral resolution observations over most of this range. The Chandra Source Catalog (CSC) includes information about X-ray sources detected in observations obtained using the Chandra X-ray Observatory. Release 2.0 of the catalog includes 317,167 point, compact, and extended sources detected in ACIS and HRC-I imaging observations released publicly prior to the end of 2014. Observed source positions and multi-band count rates are reported, as well as numerous derived spatial, photometric, spectral, and temporal calibrated source properties that may be compared with data obtained by other telescopes. Each record includes the best estimates of the properties of a source based on data extracted from all observations in which the source was detected. The Chandra Source Catalog is extracted from the CXC"s Chandra Data Archive (CDA). The CXC should be acknowledged as the source of Chandra data. For detailed information on the Chandra Observatory and datasets see: http://cxc.harvard.edu/ for general Chandra information; http://cxc.harvard.edu/cda/ for the Chandra Data Archive; http://cxc.harvard.edu/csc/ for Chandra Source Catalog information.