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2621. Chandra Lockman Area North Survey (CLANS) X-Ray Source Catalog
ID:
ivo://nasa.heasarc/clans
Title:
Chandra Lockman Area North Survey (CLANS) X-Ray Source Catalog
Short Name:
CLANS
Date:
28 Feb 2025
Publisher:
NASA/GSFC HEASARC
Description:
This table contains the catalogs for the X-ray sources detected in the Chandra Lockman Area North Survey (CLANS). (The information on the optical and infrared counterparts to these sources is contained in the CLANSOID table.) The nine ACIS-I fields which constitute the CLANS cover a solid angle of ~0.6 deg<sup>2</sup> and reach fluxes of 7 x 10<sup>-16</sup> ergs cm<sup>-2</sup> s<sup>-1</sup> (0.5-2 keV) and 3.5 x 10<sup>-15</sup> ergs cm<sup>-2</sup> s<sup>-1</sup> (2-8 keV). The authors find a total of 761 X-ray point sources. 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. CLANS consists of nine separate 70 ks Chandra ACIS-I exposures centered at J2000.0 RA and Dec of (10 46,+59 01) (see Table 2 of the reference paper for the full observational details) which were combined to create an 0.6 deg<sup>2</sup> image containing 761 sources. The CLANS observations consist of a raster with an ~2 arcminute overlap between contiguous pointings. Following the prescription in Yang et al. (2004, AJ, 128, 1501) for the CLASXS field, the authors merged the nine individual pointing catalogs to create the final CLANS X-ray catalog. For sources with more than one detection in the nine fields, they used the detection from the observation in which the effective area of the source was the largest. This table was created by the HEASARC in December 2008 based on the electronic versions of Tables 4 and 5 from the paper which were obtained from the ApJ web site. This is a service provided by NASA HEASARC .
2622. Chandra/2MASS sources in Cygnus OB2
ID:
ivo://CDS.VizieR/J/ApJ/643/238
Title:
Chandra/2MASS sources in Cygnus OB2
Short Name:
J/ApJ/643/238
Date:
21 Oct 2021
Publisher:
CDS
Description:
A 50ks Chandra observation of the unidentified TeV source in Cygnus reported by the HEGRA collaboration reveals no obvious diffuse X-ray counterpart. However, 240 point-like X-ray sources are detected within or nearby the extended TeV J2032+4130 source region, of which at least 36 are massive stars and two may be radio emitters. That the HEGRA source is a composite, having as a counterpart the multiple point-like X-ray sources we observe, cannot be ruled out. Indeed, the distribution of point-like X-ray sources appears nonuniform and concentrated broadly within the extent of the TeV source region. We offer a hypothesis for the origin of the very high energy gamma-ray emission in Cyg OB2 based on the local acceleration of TeV-range cosmic rays and the differential distribution of OB versus less massive stars in this association.
2623. Chandra multi-epoch study of the spiral gal. NGC7331
ID:
ivo://CDS.VizieR/J/ApJ/879/112
Title:
Chandra multi-epoch study of the spiral gal. NGC7331
Short Name:
J/ApJ/879/112
Date:
21 Oct 2021
Publisher:
CDS
Description:
X-ray point sources in galaxies are dominated by X-ray binaries (XRBs) that are variables or transients, and whether their variability would alter the X-ray luminosity functions (XLFs) is still in debate. Here we report on NGC 7331 as an example to test this with seven Chandra observations. Their detection limit is 7x10^37^erg/s in the energy range 0.3-8.0keV by assuming a power-law (PL) spectral model with a photon index of 1.7. We detected 55 X-ray sources. Thirteen of them are variables, of which three are transients, and some of the sources possess a bimodal feature in their luminosity-hardness ratio, which is often observed among XRBs. Nine more ultraluminous X-ray sources are found in comparison with previous studies and eight are likely to be low-mass or high-mass XRBs. Twenty-one optical counterpart candidates are found based on the Hubble Space Telescope images, but we cannot rule out the possibility of positional coincidence. The spectral analysis of SN 2014C shows a trend of increasing soft photons and decreasing hydrogen column densities as its outer shell expands. We fit the seven incompleteness-corrected XLFs to both a PL and a PL with an exponential cut-off (PLC) model using the Bayesian method, which is used for the first time in XLF fitting. The hierarchical PLC model can describe the XLF of NGC 7331 best with a slope of ~0.5 and a luminosity cut-off around 8x10^38^erg/s. This study proves that multi-epoch observations decrease the deviation due to the variable luminous sources in XLFs.
2624. Chandra Multiwavelength Plane Survey Optical ID Catalog
ID:
ivo://nasa.heasarc/champlane
Title:
Chandra Multiwavelength Plane Survey Optical ID Catalog
Short Name:
CHAMPLANE
Date:
28 Feb 2025
Publisher:
NASA/GSFC HEASARC
Description:
The authors have carried out optical and X-ray spectral analyses on a sample of 136 candidate optical counterparts of X-ray sources found in five Galactic bulge fields included in their Chandra Multiwavelength Plane (ChaMPlane) Survey. They used a combination of optical spectral fitting and quantile X-ray analysis to obtain the hydrogen column density toward each object, and a three-dimensional dust model of the Galaxy to estimate the most probable distance in each case. They present the discovery of a population of stellar coronal emission sources, likely consisting of pre-main-sequence, young main-sequence, and main-sequence stars, as well as a component of active binaries of RS CVn or BY Dra type. They identify one candidate quiescent low-mass X-ray binary with a sub-giant companion, but note that this object may also be an RS CVn system. They report the discovery of 3 new X-ray-detected cataclysmic variables (CVs) in the direction of the Galactic center (at distances <~2 kpc). This number is in excess of predictions made with a simple CV model based on a local CV space density of <~10<sup>-5</sup> pc<sup>-3</sup>, and a scale height of ~200 pc. They discuss several possible reasons for this observed excess in their paper. This table was created by the HEASARC in October 2008 based on the version of Table 5 from the paper which was obtained from the electronic ApJ web site. This is a service provided by NASA HEASARC .
2625. Chandra Multiwavelength Project (ChaMP) Point Source Catalog
ID:
ivo://nasa.heasarc/champpsc
Title:
Chandra Multiwavelength Project (ChaMP) Point Source Catalog
Short Name:
ChaMPPS
Date:
28 Feb 2025
Publisher:
NASA/GSFC HEASARC
Description:
This table represents the `Main Chandra Multiwavelength Project (ChaMP) X-Ray Point Source Catalog' and contains the basic parameters, photometry, and fluxes of 6512 ChaMP sources in 130 Chandra observations from Chandra Cycles 1 and 2. This table lists fluxes for 2 assumed spectral energy distributions with the photon indices of Gamma=1.4 and Gamma=1.7. This catalog was distributed by the ChaMP team based on the "Chandra Multiwavelength Project: X-ray Point Source Catalog (Kim et al., 2007, ApJS, 169, 401)", and was downloaded from <a href="http://hea-www.harvard.edu/CHAMP/">http://hea-www.harvard.edu/CHAMP/</a>. If you have any comments/questions on this catalog, please contact mkim @ cfa.harvard.edu or dkim @ cfa.harvard.edu. The full Chandra Multiwavelength Project (ChaMP) X-ray point source catalog lists ~ 6800 X-ray sources detected in 149 Chandra observations covering ~ 10 square degrees. The full ChaMP catalog sample is 7 times larger than the initial published ChaMP catalog (Kim et al. 2004, ApJS, 150, 19). The exposure times of the fields in this sample range from 0.9 to 124 ks, corresponding to a deepest X-ray flux limit in the 0.5 - 8.0 keV band of 9 x 10<sup>-16</sup> ergs cm<sup>-2</sup> s<sup>-1</sup>. The ChaMP X-ray data were uniformly reduced and analyzed with ChaMP-specific pipelines and then carefully validated by visual inspection. The ChaMP catalog includes X-ray photometric data in eight different energy bands as well as X-ray spectral hardness ratios and colors, source reliability, detection probability, and positional uncertainties. The false source detection rate is ~1% of all detected ChaMP sources, while the detection probability is better than ~ 95% for sources with counts >~ 30 and off-axis angle <5'. The typical positional offset between ChaMP X-ray source and their SDSS optical counterparts is 0.7" +/- 0.4", derived from ~ 900 matched sources. This HEASARC table contains the main ChaMP catalog of 6512 X-ray point sources in 130 ChaMP fields observed once and in the overlapping fields which had the longest exposures. It does not contain the supplementary ChaMP catalog of 853 sources in 19 ChaMP overlapping fields with shorter exposure times. This table was created by the HEASARC in October 2006 based on the table <a href="http://hea-www.cfa.harvard.edu/CHAMP/IMAGES_DATA/champ_xpc.tab">http://hea-www.cfa.harvard.edu/CHAMP/IMAGES_DATA/champ_xpc.tab</a> on the ChaMP website. This is a service provided by NASA HEASARC .
2626. Chandra Nearby Galaxies Point Source Catalog
ID:
ivo://nasa.heasarc/chpngptsrc
Title:
Chandra Nearby Galaxies Point Source Catalog
Short Name:
ChanNGalPSC
Date:
28 Feb 2025
Publisher:
NASA/GSFC HEASARC
Description:
The authors have analyzed Chandra ACIS observations of 32 nearby spiral and elliptical galaxies. The properties (e.g., counts in 3 energy bands, hardness ratios and inferred X-ray luminosities) of the 1441 X-ray point sources that were detected in these galaxies are listed in this table. The total point-source X-ray (0.3 - 8.0 keV) luminosity L<sub>XP</sub> is found to be well correlated with the B-band, K-band, and FIR+UV luminosities of spiral host galaxies, and is well correlated with the B-band and K-band luminosities of elliptical galaxies. This suggests an intimate connection between L<sub>XP</sub> and both the old and the young stellar populations, for which K and FIR+UV luminosities are reasonable proxies for the galaxy mass and the star formation rate (SFR). This table was created by the HEASARC in October 2006 based on CDS table J/ApJ/602/231/tablea1.dat This is a service provided by NASA HEASARC .
2627. Chandra Nearby Spiral Galaxies Point Source Catalog
ID:
ivo://nasa.heasarc/channsgpsc
Title:
Chandra Nearby Spiral Galaxies Point Source Catalog
Short Name:
ChanNSPiral
Date:
28 Feb 2025
Publisher:
NASA/GSFC HEASARC
Description:
Emission from discrete point sources dominates the X-ray luminosity in spiral galaxies. This table contains the results from a survey of 11 nearby, nearly face-on spiral galaxies observed with the Chandra X-ray Observatory in 22 observations for a total of 869 ks. The galaxies in this sample are at high Galactic latitude to minimize the absorbing column in the line of site, are nearby to minimize source confusion, and span the Hubble sequence for spirals (types 0-7), allowing insights into the X-ray source population of many diverse systems. More than 820 unique point sources are detected in at least one observation within the D25 ellipses of the galaxies. A minimum of 27% of the sources exhibit detectable long- or short-term variability, indicating a source population dominated by accreting XRBs. 17 ultraluminous X-ray sources are detected, with typical rates per galaxy of 1 or 2. In this table, source lists for the 11 galaxies are presented, along with source counts, fluxes, luminosities, X-ray colors, and variability properties. It should be noted that the X-ray source counts presented in this table are raw, background-subtracted counts, so the count rates in sources from the same galaxy that fall on different CCDs cannot be directly compared. The colors presented have been corrected for the differences between front-illuminated and back-illuminated CCDs. This table was created by the HEASARC in November 2006 based on the electronic version of Table 4 obtained from the electronic ApJ web site. This is a service provided by NASA HEASARC .
2628. Chandra normal galaxies at intermediate redshift
ID:
ivo://CDS.VizieR/J/ApJ/644/829
Title:
Chandra normal galaxies at intermediate redshift
Short Name:
J/ApJ/644/829
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have investigated 136 Chandra extragalactic sources, including 93 galaxies with narrow emission lines (NELGs) and 43 with only absorption lines (ALGs). Based on fX/fO, LX, X-ray spectral hardness, and optical emission-line diagnostics, we have conservatively classified 36 normal galaxies and 71 AGNs. Their redshift ranges from 0.01 to 1.2, with normal galaxies in the range z=0.01-0.3. Our normal galaxies appear to share characteristics with local galaxies, as expected from the X-ray binary populations and the hot interstellar matter (ISM). In conjunction with normal galaxies found in other surveys, we found no statistically significant evolution in LX/LB, within the limited z range (<~0.1).
2629. Chandra observation of M67
ID:
ivo://CDS.VizieR/J/A+A/418/509
Title:
Chandra observation of M67
Short Name:
J/A+A/418/509
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a 47-ks Chandra/ACIS observation of the old open cluster M67. We detected 25 proper-motion cluster members (including ten new sources) and 12 sources (all new) that we suspect to be members from their locations close to the main sequence (1<B-V<1.7). Of the detected members, 23 are binaries.
2630. Chandra observation of NGC 2146
ID:
ivo://CDS.VizieR/J/PASJ/57/135
Title:
Chandra observation of NGC 2146
Short Name:
J/PASJ/57/135
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present six monitoring observations of the starburst galaxy NGC 2146 using the Chandra X-ray Observatory. We detected 67 point sources in the field of view of the ACIS-S detector. Six of these sources were Ultra-Luminous X-ray Sources, the brightest of which had a luminosity of 5x10^39^erg/s. One of them, with a luminosity of ~1x10^39^erg/s, is coincident with the dynamical center location, which may be a low-luminosity active galactic nucleus. We have produced a table where the positions and main characteristics of the detected sources are reported. A comparison between the positions of the X-ray sources and those detected in NIR or radio indicates no definite counterpart. We have derived a logN-logS relation and a luminosity function. The luminosity function has a slope of 0.71 above a detection limit, which is similar to those found in other starburst galaxies. Diffuse emissions were detected in both soft (0.5-2.0keV) and hard (2.0-10.0keV) energy bands. The spectra of the diffuse component were fitted with two (hard and soft) components. The hard power-law component, with a luminosity of ~4x10^39^erg/s, is likely to have originated by unresolved point sources.

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