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171. SSA22 Field Chandra X-Ray Point Source Catalog

ID:: ivo://nasa.heasarc/ssa22cxo
Title:: SSA22 Field Chandra X-Ray Point Source Catalog
Short Name:: SSA22CXO
Date:: 18 Apr 2025
Publisher:: NASA/GSFC HEASARC
Description:: This table contains the main X-ray point-source catalog for a deep ~400-ks Chandra ACIS-I (Advanced CCD Imaging Spectrometer) exposure of the SSA22 field. The observations were centred on a z = 3.09 protocluster, which is populated by Lyman break galaxies (LBGs), Lyman-alpha emitters (LAEs) and extended Lyman-alpha-emitting blobs (LABs). The survey reached ultimate (3 count) sensitivity limits of ~5.7 x 10-17 and ~3.0 x 10-16 erg cm-2 s-1 for the 0.5-2 and 2-8 keV bands, respectively (corresponding to L(2-10 keV) ~ 5.7 x 1042 erg s-1 and L(10-30 keV) ~ 2.0 x 1043 erg s-1 at z = 3.09, respectively, for an assumed photon index of Gamma = 1.4). These limits make SSA22 the fourth deepest extragalactic Chandra survey yet conducted, and the only one focused on a known high-redshift structure. In total, the authors detect 297 X-ray point sources and identify one obvious bright extended X-ray source (not included in the current table) over a ~330 arcmin2 region. In addition to the X-ray data, the authors provide all available optical spectroscopic redshifts and near-infrared and mid-infrared photometry available for their sources. The basic X-ray and infrared properties of their Chandra sources indicate a variety of source types, although absorbed active galactic nuclei (AGN) appear to dominate. In total, they have identified 12 X-ray sources (either via optical spectroscopic redshifts or LAE selection) at z = 3.06 - 3.12 that are likely to be associated with the SSA22 protocluster. These sources have X-ray and multiwavelength properties that suggest they are powered by AGN with 0.5 - 8 keV luminosities in the range of ~ 1043 - 1045 erg s-1. The authors have analysed the AGN fraction of sources in the protocluster as a function of local LAE source density and find suggestive evidence for a correlation between AGN fraction and local LAE source density (at the ~96 per cent confidence level), implying that supermassive black hole growth at z ~3 is strongest in the highest density regions. This table was created by the HEASARC in February 2010 based on the electronic version of Table 2 from the reference paper which was obtained from the Monthly Notices web site. This is a service provided by NASA HEASARC .

172. S254-S258 Star-Forming Region Chandra X-Ray Point Source Catalog

ID:: ivo://nasa.heasarc/s254258cxo
Title:: S254-S258 Star-Forming Region Chandra X-Ray Point Source Catalog
Short Name:: S254258CXO
Date:: 18 Apr 2025
Publisher:: NASA/GSFC HEASARC
Description:: The aim of this study was to find an explanation for the remarkable morphology of the central part of the S254-S258 star forming complex. The authors performed a deep Chandra X-ray observation of the S254-S258 region in order to efficiently discriminate young stars (with and without circumstellar matter) from the numerous older field stars in the area. They detected 364 X-ray point sources in a 17' x 17' (~ 8 x 8 pc) field. This X-ray catalog provides, for the first time, a complete sample of all young stars in the region down to about 0.5 M_{sun}_. A clustering analysis identifies three significant clusters: the central embedded cluster S255-IR and two smaller clusterings in S256 and S258. Sixty-four X-ray sources can be classified as members in one of these clusters. After accounting for X-ray background contaminants, this implies that about 250 X-ray sources constitute a widely scattered population of young stars, distributed over the full field-of-view of the X-ray image. This distributed young stellar population is considerably larger than the previously known number of non-clustered young stars selected by infrared excesses. Comparison of the X-ray luminosity function with that of the Orion Nebula Cluster suggests a total population of ~ 2000 young stars in the observed part of the S254-S258 region. The S254-S258 complex was observed (PI: Preibisch) in November 2009 with the Imaging Array of the Chandra Advanced CCD Imaging Spectrometer (ACIS-I). ACIS-I provides a field of view of 17' x 17' on the sky. At the 1.6 kpc distance of S254-S258 this corresponds to 7.9 x 7.9 pc. The aimpoint of the observation was RA(J2000) = 06h12m54.0s, Dec(J2000) = +17d 59' 24". The observation was performed in the standard 'Timed Event, Faint' mode (with 3 x 3 pixel event islands). The total net exposure time of 74725 s (20.76 h) was split into two parts, separated by about 4 days. The details of these two observation parts are given in Table 1 of the reference paper. The authors first employed the wavdetect algorithm (Freeman et al. 2002, ApJS, 138, 185, a CIAO mexican-hat wavelet source detection tool) for locating X-ray sources in the merged image, and used a rather low detection threshold of 10-5. This step was performed in three different energy bands, the total band (0.5 - 8.0 keV), the soft band (0.5 - 2.0 keV), and the hard band (2.0 - 8.0) keV, and with wavelet scales between 1 and 16 pixels. They also performed a visual inspection of the images and added some 30 additional candidates to the merged catalog from the wavelet analysis, resulting in a final catalog of 511 potential X-ray sources. To clean this catalog from spurious sources, they then performed a detailed analysis of each individual candidate source with the ACIS Extract (AE hereafter) software package (Broos et al. 2010, ApJ, 714, 1582). The Poisson probability (PB) associated with the "null hypothesis", i.e. that no source exists and the extracted events are solely due to Poisson fluctuations in the local background, was computed for each source using AE. All candidate sources with PB > 0.01 were rejected as background fluctuations. After 8 iterations of this pruning procedure the final catalog consisted of 364 sources. It contains 344 primary sources with PB < 0.003, and 20 tentative sources with 0.003 < PB < 0.01. To obtain an estimate of the intrinsic, i.e. extinction-corrected, X-ray luminosity for sources that are too weak for a detailed spectral analysis, the authors used the XPHOT software, developed by Getman et al. (2010, ApJ, 708, 1760). XPHOT is based on a non-parametric method for the calculation of fluxes and absorbing X-ray column densities of weak X-ray sources. X-ray extinction and intrinsic flux are estimated from the comparison of the apparent median energy of the source photons and apparent source flux with those of high signal-to-noise spectra that were simulated using spectral models characteristic of much brighter sources of similar class previously studied in detail. This method requires at least 4 net counts per source (in order to determine a meaningful value for the median energy) and can thus be applied to 255 of the 364 sources in this table. To calculate luminosities, a distance of 1.6 kpc was assumed. The resulting intrinsic X-ray lumonosities range from 1029.4 to 1032.3 erg s-1. This table was created by the HEASARC in October 2011 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/533/A121">CDS Catalog J/A+A/533/A121</a> files table2.dat, table3.dat and table5.dat. This is a service provided by NASA HEASARC .

173. Star Formation in Nearby Clouds (SFiNCs) X-Ray Source Catalog

ID:: ivo://nasa.heasarc/sfincsxray
Title:: Star Formation in Nearby Clouds (SFiNCs) X-Ray Source Catalog
Short Name:: SFINCSXRAY
Date:: 18 Apr 2025
Publisher:: NASA/GSFC HEASARC
Description:: The Star Formation in Nearby Clouds (SFiNCs) project is aimed at providing a detailed study of the young stellar populations and of star cluster formation in the nearby 22 star-forming regions (SFRs) for comparison with our earlier MYStIX survey of richer, more distant clusters. As a foundation for the SFiNCs science studies, in the reference paper homogeneous data analyses of the Chandra X-ray and Spitzer mid-infrared archival SFiNCs data are described, and the resulting catalogs of over 15,300 X-ray and over 1,630,000 mid-infrared point sources are presented. On the basis of their X-ray/infrared properties and spatial distributions, nearly 8500 point sources have been identified as probable young stellar members of the SFiNCs regions. Compared to the existing X-ray/mid-infrared publications, the SFiNCs member list increases the census of YSO members by 6%-200% for individual SFRs and by 40% for the merged sample of all 22 SFiNCs SFRs. Sixty-five X-ray observations of the 22 SFiNCs SFRs made with the imaging array on the Advanced CCD Imaging Spectrometer (ACIS) were extracted from the Chandra archive (spanning from 2000 January to 2015 April). See Tables 1 and 2 of the reference paper for the list of SFRs and the log of Chandra ACIS observations, respectively. The final Chandra-ACIS catalog for the 22 SFiNCs SFRs comprises 15,364 X-ray sources (presented in Tables 3 and 4 and section 3.2 of the reference paper, and the contents of this HEASARC table, SFINCSXRAY). To obtain MIR photometry for X-ray objects and to identify and measure MIR photometry for additional non-Chandra disky stars that were missed in previous studies of the SFiNCs regions (typically faint YSOs), the authors have reduced the archived Spitzer-IRAC data by homogeneously applying the MYStIX-based Spitzer-IRAC data reduction methods of Kuhn et al. (2013, ApJS, 209, 29) to the 423 Astronomical Object Request (AORs) data sets for the 22 SFiNCs SFRs (Table 5 of the reference paper). As in MYStIX, the SFiNCs IRAC source catalog retains all point sources with the photometric signal-to-noise ratio > 5 in both [3.6] and [4.5] um channels. This catalog covers the 22 SFiNCs SFRs and their vicinities on the sky and comprises 1,638,654 IRAC sources with available photometric measurements for 100%, 100%, 29%, and 23% of these sources in the 3.6, 4.5, 5.8, and 8.0um bands, respectively (see table 6 and section 3.4 of the reference paper). Source position cross-correlations between the SFiNCs Chandra X-ray source catalog and an IR catalog, either the "cut-out" IRAC or 2MASS, were made using the steps described in section 3.5 of the reference paper. Tables 7 and 8 of the reference paper provide the list of 8,492 SFiNCs probable cluster members (SPCMs) and their main IR and X-ray properties (see section 4 of the reference paper): this list as available at the HEASARC as the SFINCSPCM table (q.v.). This table was created by the HEASARC in September 2017 based on the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/229/28">CDS Catalog J/ApJS/229/28</a> files table3.dat (the list of SFiNCs X-ray sources and their basic properties) and table4.dat (the list of SFiNCs X-ray source fluxes). This is a service provided by NASA HEASARC .

174. Trifid Nebula (M 20) Chandra X-Ray Point Source Catalog

ID:: ivo://nasa.heasarc/trifidcxo
Title:: Trifid Nebula (M 20) Chandra X-Ray Point Source Catalog
Short Name:: TRIFIDCXO
Date:: 18 Apr 2025
Publisher:: NASA/GSFC HEASARC
Description:: This table contains a list of the Trifid Nebula (M 20) X-Ray point sources detected by the Chandra X-ray Observatory (CXO) in an observation carried out on 2002 June 13. The Trifid Nebula, a young star-forming H II region, was observed for 16 hr by the Advanced CCD Imaging Spectrometer imaging array, ACIS-I, detector. 304 X-ray sources were detected, 30% of which are hard sources (defined as those sources having a 0.5-2.0 keV to 2.0-8.0 keV hardness ratio > -0.2) and 70% of which have near-infrared counterparts. This table was created by the HEASARC in January 2007 based on CDS table J/ApJ/607/904/table1.dat. This is a service provided by NASA HEASARC .

175. 47 Tuc Globular Cluster Chandra X-Ray Point Source Catalog (2005 Version)

ID:: ivo://nasa.heasarc/gc47tuccxo
Title:: 47 Tuc Globular Cluster Chandra X-Ray Point Source Catalog (2005 Version)
Short Name:: GC47TUCCXO
Date:: 18 Apr 2025
Publisher:: NASA/GSFC HEASARC
Description:: The authors have detected 300 X-ray sources within the half-mass radius (2.79') of the globular cluster 47 Tucanae in a deep (281 ks) Chandra exposure. They perform photometry and simple spectral fitting for our detected sources and construct luminosity functions, X-ray color-magnitude, and color-color diagrams. Eighty-seven X-ray sources show variability on timescales from hours to years. Thirty-one of the new X-ray sources are identified with chromospherically active binaries from the catalogs of Albrow and coworkers (2001, <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/559/1060">CDS Catalog <J/ApJ/559/1060></a>). The authors estimate that the total number of neutron stars in 47 Tuc is of order 300, reducing the discrepancy between theoretical neutron star retention rates and observed neutron star populations in globular clusters. The data used in this paper are from the 2000 and 2002 Chandra observations of the globular cluster 47 Tuc. The 2000 observations, initially described in Grindlay et al. (2001, Science 292, 2290), were performed with the ACIS-I CCD array at the telescope focus, while the 2002 observations placed the back-illuminated ACIS-S aim point at the focus for maximum low-energy sensitivity. The authors combined the results from wavdetect source detection runs with a threshold probability of 1 x 10-5, in two energy bands (0.5 - 2.0 keV and 0.5 - 6.0 keV for the 2000 observations, and (0.3 - 2.0 keV and 0.3 - 6.0 keV for the 2002 observations), to make independent source lists for the 2000 and 2002 observations, given in Tables 2 and 3 of the reference paper, which have been combined in the present HEASARC table. A total of 146 sources were detected in this way in the 2000 observations (entries with dataset_year = 2000), while 300 sources were detected in the 2002 observations (dataset_year = 2002). A total of 143 of the sources were clearly detected in both observations, while only three of the sources from the 2000 observations were not detected in the 2002 observations. See also the related <a href="gc47tuccx2.html">2017 source catalog</a>. This table was created by the HEASARC in June 2007 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/625/796">CDS Catalog J/ApJ/625/796</a> files table2.dat, table3.dat, and (part of) table5.dat. This is a service provided by NASA HEASARC .

176. 47 Tuc Globular Cluster Chandra X-Ray Point Source Catalog (2017 Version)

ID:: ivo://nasa.heasarc/gc47tuccx2
Title:: 47 Tuc Globular Cluster Chandra X-Ray Point Source Catalog (2017 Version)
Short Name:: GC47TUCCX2
Date:: 18 Apr 2025
Publisher:: NASA/GSFC HEASARC
Description:: The authors combined Chandra ACIS observations of the globular cluster 47 Tucanae (47 Tuc) from 2000, 2002, and 2014-2015 to create a deeper X-ray source list and study some of the faint radio millisecond pulsars (MSPs) present in this cluster. This work combined 180 ks of new Chandra ACIS data on 47 Tuc with 370 ks of archival data and used improved algorithms to generate a new source catalog, finding 81 new sources for a total of 370 within the half-mass region (2.79 arcsec) of the cluster. The majority of the newly identified sources are in the crowded core region, indicating cluster membership. The authors associated five of the new X-ray sources with chromospherically active BY Dra or W UMa variables identified by Albrow et al. (2001, <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/559/1060">CDS Cat. <J/ApJ/559/1060></a>). See also the related <a href="gc47tuccxo.html">2005 source catalog</a>. This table was created by the HEASARC in September 2020 based upon the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/MNRAS/472/3706">CDS Catalog J/MNRAS/472/3706</a> files table2.dat, table4.dat, and table5.dat. The optical names from Albrow et al. (2001) were subsequently corrected in October 2020 in order to use the recommendation from the CDS Dictionary of Nomenclature of Celestial Objects. This is a service provided by NASA HEASARC .

177. Ultraluminous X-Ray Sources in Nearby Galaxies Catalog

ID:: ivo://nasa.heasarc/ulxngcat
Title:: Ultraluminous X-Ray Sources in Nearby Galaxies Catalog
Short Name:: ULXNGCAT
Date:: 18 Apr 2025
Publisher:: NASA/GSFC HEASARC
Description:: One hundred and seven ultraluminous X-ray sources (ULXs) with 0.3-10.0 keV luminosities in excess of 1039 erg s-1 are identified in a complete sample of 127 nearby galaxies. The sample includes all galaxies within 14.5 Mpc above the completeness limits of both the Uppsala Galaxy Catalogue and the Infrared Astronomical Satellite survey. The galaxy sample spans all Hubble types, a four-decade range in mass, 7.5 < log (M/Msun) < 11.4, and in star formation rate, 0.0002 < SFR(Msun yr-1) <= 3.6. ULXs are detected in this sample at rates of one per 3.2 x 1010 Msun, one per ~0.5 Msun yr-1 star formation rate, and one per 57 Mpc3 corresponding to a luminosity density of ~2 x 1037 erg s-1 Mpc-3. At these rates, the authors estimate as many as 19 additional ULXs remain undetected in fainter dwarf galaxies within the survey volume. An estimated 14 objects, or 13%, of the 107 ULX candidates are expected to be background sources. The differential ULX luminosity function shows a power-law slope alpha ~ -0.8 to -2.0 with an exponential cutoff at ~20 x 1039 erg s-1 with precise values depending on the model and on whether the ULX luminosities are estimated from their observed numbers of counts or, for a subset of candidates, from their spectral shapes. Extrapolating the observed luminosity function predicts at most one very luminous ULX, LX ~ 1041 erg s-1, within a distance as small as 100 Mpc. The luminosity distribution of ULXs within the local universe cannot account for the recent claims of luminosities in excess of 2 x 1041 erg s-1, requiring a new population class to explain these extreme objects. This table was created by the HEASARC in November 2011 based on an electronic version of Table 1 from the reference paper that was obtained from the ApJ web site. This is a service provided by NASA HEASARC .

178. VLA Extended-Chandra Deep Field-South 1.4-GHz Sources Opt/IR Counterparts

ID:: ivo://nasa.heasarc/vlaecdfsoi
Title:: VLA Extended-Chandra Deep Field-South 1.4-GHz Sources Opt/IR Counterparts
Short Name:: VLAECDFSOI
Date:: 18 Apr 2025
Publisher:: NASA/GSFC HEASARC
Description:: This table contains a sample of 883 sources detected in a deep Very Large Array (VLA) survey at 1.4 GHz in the Extended-Chandra Deep Field South (E-CDFS). The reference paper focuses on the identification of their optical and infrared (IR) counterparts. The authors use a likelihood-ratio technique that is particularly useful when dealing with deep optical images to minimize the number of spurious associations. They find a reliable counterpart for 95% of their radio sources. Most of the counterparts (74%) are detected at optical wavelengths, but there is a significant fraction (21%) that are only detectable in the IR. Combining newly acquired optical spectra with data from the literature, the authors are able to assign a redshift to 81% of the identified radio sources (37% spectroscopic). They also investigate the X-ray properties of the radio sources using the Chandra 4 Ms and 250 ks observations. In particular, the authors use a stacking technique to derive the average properties of radio objects undetected in the Chandra images. The results of their analysis are collected in this new catalog containing the position of the optical/IR counterpart, the redshift information, and the X-ray fluxes. It is the deepest multi-wavelength catalog of radio sources, which will be used for future study of this galaxy population. The E-CDFS was observed at 1.4 GHz with the VLA between 2007 June and September (Miller et al. 2008, ApJS, 179, 114). The mosaic image covered an area of about 34 by 34 arcminutes with near-uniform sensitivity. The typical rms is 7.4 µJy for a 2.8 by 1.6 arcseconds beam. The second data release (N. Miller et al. 2012, in preparation) provides a new source catalog with a 5-sigma point-source detection limit, for a total of 883 sources. The median value of the distribution is 58.5 µJy and the median signal-to-noise ratio (S/N) is 7.6. The authors note that ~ 90% of the sample has a flux density below 1 mJy, a regime where radio-quiet AGNs and star-forming galaxies (SFGs) become the dominant populations This table was created by the HEASARC in November 2012 based on the files table3.dat and table5.dat which were obtained from the ApJS web site. This is a service provided by NASA HEASARC .

179. Westerlund 1 Chandra X-Ray Point Source Catalog

ID:: ivo://nasa.heasarc/wd1cxo
Title:: Westerlund 1 Chandra X-Ray Point Source Catalog
Short Name:: WD1CXO
Date:: 18 Apr 2025
Publisher:: NASA/GSFC HEASARC
Description:: The nature of the X-ray point source population within the young massive cluster Westerlund 1 (Wd 1) is investigated. Chandra X-ray Observatory (CXO) observations were used to determine the X-ray properties of emitters within Wd 1, while a comprehensive multi-wavelength dataset was employed to constrain their nature. Wd 1 (l=339.5, b=-0.4) was observed with the CXO Advanced CCD Spectrometer Spectroscopic array on 2005 May 22 for 18 ks (sequence 6283) and 2005 June 20 for 42 ks (sequence 5411). 241 sources were found above a sensitivity threshold that corresponded to a 10-6 chance per PSF element of detecting a spurious source. X-ray emission from a multitude of different stellar sources within Wd 1, including both evolved high mass and low-mass pre-MS stars, is found. This table was created by the HEASARC in May 2008 based on CDS table J/A+A/477/147 files table1.dat and table3.dat. This is a service provided by NASA HEASARC .

180. W 40 Star-Forming Region Chandra X-Ray Point Source Catalog

ID:: ivo://nasa.heasarc/w40sfrcxo
Title:: W 40 Star-Forming Region Chandra X-Ray Point Source Catalog
Short Name:: W40SFRCXO
Date:: 18 Apr 2025
Publisher:: NASA/GSFC HEASARC
Description:: The young stellar cluster illuminating the W40 H II region, one of the nearest massive star-forming regions (SFRs), has been observed with the ACIS detector on board the Chandra X-ray Observatory. Due to its high obscuration, this is a poorly studied stellar cluster with only a handful of bright stars visible in the optical band, including three OB stars identified as primary excitation sources. The authors detect 225 X-ray sources, of which 85% are confidently identified as young stellar members of the region. Two potential distances of the cluster, 260 pc and 600 pc, are used in the paper. Supposing the X-ray luminosity function of SFRs to be universal, it supports a 600 pc distance as a lower limit for W40 and a total population of at least 600 stars down to 0.1 Msun under the assumption of a coeval population with a uniform obscuration. In fact, there is strong spatial variation in Ks-band-excess disk fraction and non-uniform obscuration due to a dust lane that is identified in absorption in optical, infrared, and X-ray. The dust lane is likely part of a ring of material which includes the molecular core within W40. In contrast to the likely ongoing star formation in the dust lane, the molecular core is inactive. The star cluster has a spherical morphology, an isothermal sphere density profile, and mass segregation down to 1.5 Msun. However, other cluster properties, including a <= 1 Myr age estimate and ongoing star formation, indicate that the cluster is not dynamically relaxed. X-ray diffuse emission and a powerful flare from a young stellar object are also reported in the reference paper. This table was created by the HEASARC in March 2011 based on electronic versions of Tables, 1, 2 and 4 of the reference paper which were obtained from the ApJ web site. This is a service provided by NASA HEASARC .

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171. SSA22 Field Chandra X-Ray Point Source Catalog

172. S254-S258 Star-Forming Region Chandra X-Ray Point Source Catalog

173. Star Formation in Nearby Clouds (SFiNCs) X-Ray Source Catalog

174. Trifid Nebula (M 20) Chandra X-Ray Point Source Catalog

175. 47 Tuc Globular Cluster Chandra X-Ray Point Source Catalog (2005 Version)

176. 47 Tuc Globular Cluster Chandra X-Ray Point Source Catalog (2017 Version)

177. Ultraluminous X-Ray Sources in Nearby Galaxies Catalog

178. VLA Extended-Chandra Deep Field-South 1.4-GHz Sources Opt/IR Counterparts

179. Westerlund 1 Chandra X-Ray Point Source Catalog

180. W 40 Star-Forming Region Chandra X-Ray Point Source Catalog

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