- ID:
- ivo://nasa.heasarc/lmcn11cxo
- Title:
- LMC N11 Giant HII Region Chandra X-Ray Point Source Catalog
- Short Name:
- LMCN11CXO
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- A very sensitive X-ray investigation of the giant H II region N11 in the Large Magellanic Cloud (LMC) was performed using the Chandra X-ray Observatory in which 165 point sources were detected. The 300-ks observation reveals X-ray sources with luminosities (if at the 50 kpc distance of the LMC) down to 10<sup>32</sup> erg s<sup>-1</sup>, increasing the number of known point sources in the field by more than a factor of five. Among these detections are 13 massive stars (3 compact groups of massive stars, 9 O stars, and one early B star) with log(L<sub>X</sub>/L<sub>BOL</sub>) ~ -6.5 to -7, which may suggest that they are highly magnetic or colliding-wind systems. On the other hand, the stacked signal for regions corresponding to undetected O stars yields log(L<sub>X</sub>/L<sub>BOL</sub>) ~ -7.3, i.e., an emission level comparable to similar Galactic stars despite the lower metallicity. Other point sources coincide with 11 foreground stars, 6 late-B/A stars in N11, and many background objects. This observation also uncovers the extent and detailed spatial properties of the soft, diffuse emission regions, but the presence of some hotter plasma in their spectra suggests contamination by the unresolved stellar population. The Chandra ACIS-I observations of N11 were made in six separate segments within two months in 2007. As summarized in Table 1, the exposure time of each segment was 42-49 ks and the roll angle ranged from 130 to 188 degrees Cleaning of significant background flares, together with a correction for the dead time of the six observations, resulted in a total of 280 ks useful exposure for the subsequent analysis. A combination of source detection algorithms (wavelet, sliding-box, and maximum likelihood centroid fitting) were applied to unsmoothed data in three bands: soft (S): 0.5-2.0 keV, hard (H): 2-8 keV, and total (T): 0.5-8 keV. The final source list contains 165 sources with local false detection probability P < 10<sup>-6</sup> in at least one band (Poisson statistics were used in calculating the significance of a source detection above the local count background). The source detection, though optimized for point-like sources, includes a few strong peaks of diffuse X-ray emission, chiefly associated with the SNR N11L, which lies about ~7' west of the field center. The authors calculated the net (background-subtracted) count rates in four sub-bands (S1 = 0.5-1.0 keV, S2 = 1-2 keV, H1 = 2-4 keV and H2 = 4-8 keV, which were later added to form the count rates in the broader bands (S, H, and T). Source counts for each sub-band were then extracted within the 70% energy-encircled radius (EER) of the PSF, whose size depends on the off-axis angle of the source in the exposure and of the energy band under consideration. A background correction was also applied. Finally, count rates were derived by dividing source net counts by their effective exposure times (values at the source positions in the exposure map of the energy band under consideration), leading to equivalent on-axis values. It should be noted that the presented count rates have thus been corrected for the full PSF and for the effective exposure, which accounts not only for the telescope vignetting, but also for the degradation of the detector sensitivity over time. Therefore, the actual number of counts in a detection aperture is not simply a count rate multiplied by an exposure of 280 ks. The difference could be up to a factor of ~2, depending on a source's spectral shape. The authors searched for counterparts to their X-ray sources in several catalogs: the USNO-B1.0 Catalog (Monet et al. 2003), the Guide Star Catalog V2.3.2 (GSC, Lasker et al. 2008), the 2MASS All-Sky Catalog of Point Sources (Cutri et al. 2003), the Magellanic Clouds Photometric Survey (MCPS; Zaritsky et al. 2004, AJ, 128, 1606), the IRSF Magellanic Clouds Point Source Catalog (Kato et al. 2007, PASJ, 59, 615)), the DENIS Catalogue toward Magellanic Clouds (DCMC; Cioni et al. 2000, A&AS, 144, 235), and JHK<sub>s</sub> photometry of N11 young stellar objects ([HKN2006]; Hatano et al. 2006, AJ, 132, 2653). A best correlation radius of 1" was found to be optimal and was thus used to derive the final list of optical and infrared counterparts to the Chandra X-ray sources: 71 of the 165 sources have at least one counterpart within 1". The HEASARC has modified the counterpart names given in this table compared to those given in the reference paper so that they comply with the forms recommended by the CDS Dictionary of Nomenclature of Celestial Objects. This table was created by the HEASARC in August 2014 based primarily on the contents of Tables 2, 3 and 4 from the reference paper, machine-readable versions of which were obtained from the ApJS web site. Some information from Table 8 of the reference paper, viz., a number of the spectral types quoted for individual stars, was also used in populating the HEASARC-created class parameter. This is a service provided by NASA HEASARC .
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- ID:
- ivo://nasa.heasarc/moxc
- Title:
- Massive Star-Forming Regions Omnibus X-Ray Catalog
- Short Name:
- MOXC
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the Massive Star-forming Regions (MSFRs) Omnibus X-ray Catalog (MOXC), a compendium of X-ray point sources from Chandra/ACIS observations of a selection of MSFRs across the Galaxy, plus 30 Doradus in the Large Magellanic Cloud. MOXC consists of 20,623 X-ray point sources from 12 MSFRs with distances ranging from 1.7 kpc to 50 kpc, and comprises Table 3 of the reference paper. In their paper, the authors show the morphology of the unresolved X-ray emission that remains after the cataloged X-ray point sources are excised from the ACIS data, in the context of Spitzer and WISE observations that trace the bubbles, ionization fronts, and photon-dominated regions that characterize MSFRs. In previous work, they have found that this unresolved X-ray emission is dominated by hot plasma from massive star wind shocks. This diffuse X-ray emission is found in every MOXC MSFR, clearly demonstrating that massive star feedback (and the several-million-degree plasmas that it generates) is an integral component of MSFR physics. The Chandra observations used for the Massive Star-forming Regions Omnibus X-ray Catalog (MOXC) are summarized in Table 2 of the reference paper and have dates ranging from 2000-04-03 to 2013-01-31 for the 12 MSFRs: the 7 MYStIX targets NGC 6334, NGC 6357, M 16, M 17, W 3, W 4 and NGC 3576, and the 5 "beyond-MYStIX" targets G333.6-0.2, W 51A, G29.96-0.02, NGC 3603 and 30 Doradus. A similar table to MOXC for other MYStIX targets was presented by Kuhn et al. (2013, ApJS, 209, 27, available as the HEASARC MYSTIXXRAY table). The main difference between that table and the MOXC version is that the present authors have chosen to omit absorption-corrected X-ray source luminosities from the XPHOT algorithm (Getman et al. 2010, ApJ, 708, 1760) herein, because those quantities are given in Broos et al. (2013, ApJS, 209, 32, available as the HEASARC MYSTIXMPCM table) for relevant MYStIX X-ray sources (those classified as pre-main sequence stars). For beyond-MYStIX targets, the authors chose to postpone XPHOT calculations until the X-ray sources were classified, since XPHOT estimates are only appropriate for pre-MS stars. The XPHOT code is available (Getman et al. 2012, Astrophysics Source Code Library, record ascl.soft12002) if others wish to use it on MOXC sources. All photometric quantities in this table are apparent (not corrected for absorption). The HEASARC has used prefixes 'fb_', 'sb_' and 'hb_' (replacing the suffixes '_t', '_s' and '_h' used in the reference paper) on the names of the X-ray photometric quantities which designate the full (total, 0.5 - 8 keV), soft (0.5 - 2.0 keV) and hard (2-8 keV) energy bands. Correction for finite extraction apertures is applied to the ancillary reference file (ARF) calibration products (see Broos et al. 2010, ApJ, 714, 1582, Section 5.3); the total_counts and counts quantities characterize the extraction and are not aperture-corrected. The only calibrated quantities presented are the apparent photon fluxes, in units of photon cm<sup>-2</sup> s<sup>-1</sup> (see Broos et al. 2010, ApJ, 714, 1582, Section 7.4), and estimates for the apparent energy fluxes, in units of erg cm<sup>-2</sup> s<sup>-1</sup> (Getman et al. 2010, ApJ, 708, 1760). This table was created by the HEASARC in October 2014 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/213/1">CDS Catalog J/ApJS/213/1</a> files table3.dat (the MOXC X-ray Source Catalog) and table6.dat (the list of MOXC sources in previously published Chandra catalogs). This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/mystixmpcm
- Title:
- MassiveYoungStar-FormingComplexStdyinIR&X-Rays:MYStIXProbComplexMbrs
- Short Name:
- MYSTIXMPCM
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Massive Young Star-forming complex Study in Infrared and X-rays (MYStIX) project requires samples of young stars that are likely members of 20 nearby Galactic massive star-forming regions. Membership is inferred from statistical classification of X-ray sources, from detection of a robust infrared excess that is best explained by circumstellar dust in a disk or infalling envelope and from published spectral types that are unlikely to be found among field stars. This table contains the MYStIX membership lists, which total 31,549 probable complex members. In their reference paper, the authors describe in detail the statistical classification of X-ray sources via a "Naive Bayes Classifier". These membership lists provide the empirical foundation for subsequent MYStIX science studies. The MYStIX project, described by Feigelson et al. (2013, ApJS, 209, 26), seeks to identify and study samples of young stars in 20 nearby (0.4 < D < 3.6kpc) Galactic massive star-forming regions (MSFRs). These samples are derived using X-ray data from the Chandra X-ray Observatory, near-infrared (NIR) photometry from the United Kingdom InfraRed Telescope (UKIRT) and from the Two Micron All Sky Survey (2MASS), mid-infrared (MIR) photometry from the Spitzer Space Telescope, and from published spectroscopically-identified massive stars. The purpose of this study is to describe the authors' efforts to minimize contaminants in the MYStIX catalogs of young stars. They refer to these latter objects as the "MYStIX Probable Complex Members" or MPCMs. This table contains the combined MPCM catalog for all 20 of the MYStIX MSFRs. This MPCM catalog is the union of three sets of probable members identified by three different established methods for identifying young stars (see Feigelson et al. 2013, ApJS, 209, 26, Fig. 3). Most of the X-ray information on the MPCMs (with the exception of the X-ray luminosities and absorbing column densities obtained using XPHOT) was produced by the ACIS Extract (AE) software package (Broos et al. 2010, ApJ, 714, 1582 and 2012, Astrophysics Source Code Library, 1203.001). The AE software and User's Guide are available at <a href="http://www.astro.psu.edu/xray/acis/acis_analysis.html">http://www.astro.psu.edu/xray/acis/acis_analysis.html</a>. X-ray quantities using the 'fb' prefix are for the full or total energy band from 0.5 - 8.0 keV, those using the 'sb' prefix are for the soft band from 0.5 - 2.0 keV, and those using the 'hb' prefix are for the hard band from 2.0 - 8.0 keV. L. K. Townsley and P. S. Broos (2013, in preparation) and Kuhn et al. (2013, ApJS, 209, 27) identify a few very bright X-ray sources in each region that suffer from a type of instrumental non-linearity known as photon pile-up (<a href="http://cxc.harvard.edu/ciao/why/pileup_intro.html">http://cxc.harvard.edu/ciao/why/pileup_intro.html</a>); X-ray properties reported for those sources are biased and should be used with caution. This table was created by the HEASARC in February 2014 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/209/32">CDS Catalog J/ApJS/209/32</a> file mpcm.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/mystixxray
- Title:
- MassiveYoungStar-FormingComplexStudyinIR&X-Rays:X-RaySourceCatalog
- Short Name:
- MYSTIXXRAY
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Massive Young Star-forming complex Study in Infrared and X-ray (MYStIX) uses data from the Chandra X-Ray Observatory to identify and characterize the young stellar populations in 20 Galactic (d < 4 kpc) massive star-forming regions. In this present study, the X-ray analysis for Chandra ACIS-I observations of 10 of the MYStIX fields is described, and a catalog of > 10,000 X-ray sources is presented in this table. In comparison to other published Chandra source lists for the same regions, the number of MYStIX-detected faint X-ray sources in a region is often doubled. While the higher catalog sensitivity increases the chance of false detections, it also increases the number of matches to infrared stars. X-ray emitting contaminants include foreground stars, background stars, and extragalactic sources. The X-ray properties of sources in these classes are discussed in the reference paper. The X-ray observations were made with the imaging array on the Advanced CCD Imaging Spectrometer (ACIS-I) on board the Chandra X-Ray Observatory. This array of four CCD detectors subtends 17' x 17' on the sky. The number of different Chandra pointings for each region, the total exposures for these pointings, and details of how the observations were taken are provided in Table 1 of the reference paper. Overall, 29 Chandra ObsIDs are included with typical integration times for a pointing of 40 - 100 ks, sufficient to detect most OB stars and lower-mass pre-main-sequence stars down to ~ 0.5 - 1 solar masses for the MYStIX regions. The 10 MYStIX MSFRs treated herein are listed in Table 2 of the reference paper. The data were acquired from the Chandra Data Archive from 2001 Jan to Mar 2008 for 10 MYStIX fields (the Flame Nebula, RCW 36, NGC 2264, the Rosette Nebula, the Lagoon Nebula, NGC 2362, DR 21, RCW 38, Trifid Nebula and NGC 1893). The X-ray photometry is from Broos et al. (2010, ApJ, 714, 1582; ACIS Extract); see also the CCCP, Broos et al. (2011, ApJS, 194, 2). The source significance quantities (fb_prob_no_src, sb_prob_no_src, hb_prob_no_src and prob_no_src_min) are computed using a subset of each source's extractions chosen to maximize significance (Broos et al. 2010, ApJ, 714, 1582, Section 6.2). The source position and positional uncertainty quantities are computed using a subset of each source's extractions chosen to minimize the position uncertainty (Broos et al. 2010, ApJ, 714, 1582, Sections 6.2 and 7.1). All other quantities are computed using a subset of each source's extractions chosen to balance the conflicting goals of minimizing photometric uncertainty and of avoiding photometric bias (Broos et al. 2010, ApJ, 714, 1582, Sections 6.2 and 7). The observed and absorption-corrected energy fluxes and their associated errors and the estimated hydrogen column densities and their uncertainties are derived using non-parametric procedures (XPHOT, Getman et al. 2010, ApJ, 708, 1760). XPHOT assumes the X-ray spectral shapes of young, low-mass stars, which come from coronal X-ray emission. XPHOT quantities will therefore be unreliable for high-mass stars, for which X-ray emission is associated with the stellar wind. This table was created by the HEASARC in January 2014 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/209">CDS Catalog J/ApJS/209</a> 27 file xmystix.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/m31cxo2
- Title:
- M 31 Bulge Chandra X-Ray Point Source Catalog
- Short Name:
- M31CXO2
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The authors explore the population of X-ray point sources in the bulge of M 31 so as to contrast properties of various subpopulations, such as persistent and transient sources and primordial LMXBs and dynamically formed ones. Based on the data from 26 archival Chandra ACIS observations with aim-points within 10 arcminutes of the center of M 31 (J2000 coordinates of 00:42:44.31, +41:16:09.4), the authors study the source content and properties of various subpopulations of X-ray sources to a maximum distance of 12 arcminutes from the center of M 31. To a limiting luminosity of ~10<sup>35</sup> erg s<sup>-1</sup>, the authors find 263 X-ray point sources, with ~1/3 of these being background galaxies. A study of the spatial distribution and the luminosity function of the X-ray sources shows that the distribution of primordial LMXBs is consistent with the distribution of the K-band light and that their luminosity function flattens below ~10<sup>37</sup> erg s<sup>-1</sup> to the dN/dL ~ L<sup>-1</sup> law in agreement with the behavior found earlier for LMXBs in the Milky Way and in Cen A. Within a radius of 12 arcminutes, the luminosity function is independent of distance to the center of M 31, in contrast to earlier Chandra studies. The LMXBs located in globular clusters and within ~1 arcminute from the center of M 31 are presumably created via dynamical interactions. The dynamical origin of the r < 1 arcminute sources is strongly suggested by their radial distribution which follows the rho<sub>*</sub><sup>2</sup> profile rather than the K-band light distribution. Their luminosity function shows a prominent fall-off below log(L<sub>X</sub>) <~ 36.5. Although the statistics are insufficient to claim a genuine low-luminosity cut-off in the luminosity function, the best fit power-law with a slope of -0.6 +/- 0.2 is significantly flatter than the dN/dL ~ L<sup>-1</sup> law. The authors also searched for transients and found 28 sources that varied by a factor larger than 20. Their spatial distribution follows the distribution of the persistent LMXBs within the accuracy allowed by the limited number of transients. This HEASARC table was created in March 2010 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/468/49">CDS catalog J/A+A/468/49</a> file table2.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/m31cfcxo
- Title:
- M 31 Central Field Chandra HRI X-Ray Point Source Catalog
- Short Name:
- M31CFCXO
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The central field of the Andromeda galaxy (M 31) was monitored from 2006 to 2012 using the Chandra HRC-I detector (about 0.1 - 10 keV energy range) with the main aim of detecting X-rays from optical novae. The authors present a systematic analysis of all X-ray sources found in the 41 nova monitoring observations, along with 23 M 31 central field HRC-I observations available from the Chandra data archive starting in December 1999. Based on these observations, they studied the X-ray long-term variability of the source population and especially of the X-ray binaries in M31. The authors created a catalog of sources detected in the 64 available observations that adds up to a total exposure time of about 1 Ms. To study the variability, they developed a processing pipeline to derive long-term Chandra HRC-I light curves for each source over the 13 years of observations, and also searched for extended X-ray sources in the merged images. This table contains the point-source catalog of 318 X-ray sources with detailed long-term variability information, 28 of which are published for the first time. The spatial and temporal resolution of the catalog allows the authors to classify 115 X-ray binary candidates showing high X-ray variability or even outbursts, as well as 14 globular cluster X-ray binary candidates showing no significant variability. The analysis may suggest that outburst sources are less frequent in globular clusters than in the field of M 31. Seven supernova remnants (not included in the point-source catalog) were detected, one of which is a new candidate, and also the first X-rays from a known radio supernova remnant were resolved. In addition to 33 known optical nova/X-ray source correlations, the authors discovered one previously unknown super-soft X-ray outburst and several new nova candidates. A large sample of detailed long-term X-ray light curves of sources in the M31 central field has been obtained in this study (see Appendix B.1 of the reference paper), which helps in understanding the X-ray population of our neighboring spiral galaxy M 31. Based on all the available Chandra HRC-I observations (see Table A.1 in the reference paper for the complete list), a source catalog has been created (available in this HEASARC table) and the energy flux of each source in every individual observation derived (these are not available in this HEASARC table, but are obtainable at the CDS: for more details, see the files <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A%2BA/555/A65/ReadMe">https://cdsarc.cds.unistra.fr/ftp/cats/J/A%2BA/555/A65/ReadMe</a> and <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J_A%2BA/555/A65/table2.dat.gz">https://cdsarc.cds.unistra.fr/ftp/cats/J_A%2BA/555/A65/table2.dat.gz</a>). One thing to be aware of is that, in the latter file, upper limits are denoted by a '>' symbol rather than the more usual '<' symbol!). These fluxes were calculated assuming a generic power law spectrum and Galactic foreground absorption for each source. This table was created by the HEASARC in August 2013 based on the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/555/A65">CDS catalog J/A+A/555/A65</a> files table1.dat and xcorr.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/m31cxoxray
- Title:
- M 31 Central Region Chandra X-Ray Point Source Catalog
- Short Name:
- Chan/M31
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table countains the M 31 Central Region Catalog of Chandra X-Ray Point Sources. It is based on Chandra observations of the central region of M 31. By combining eight Chandra ACIS-I observations which were taken between 1999 and 2001, the authors have identified 204 X-ray sources within the central ~17'x17' region of M 31, with a detection limit of ~2x10<sup>35</sup> erg/s. Of these 204 X-ray sources, 22 are identified with globular clusters, two with supernova remnants, nine with planetary nebulae, and nine with supersoft sources. By comparing individual images, about 50% of the sources were found to be variable on timescales of months. The authors also found 13 transients, with light curves showing a variety of shapes. They also extracted the energy spectra of the 20 brightest sources; they can be well fitted by a single power law with a mean photon index of 1.8. The spectral shapes of 12 sources were variable, suggesting that they went through state changes. All sources in the catalog have S/N > 2.5 and only five have S/N < 3.0. The detection limit for the sources varies across the image due to the variation of exposure time, background, and instrumental PSF, and is highest near the edges, where the PSF broadens rapidly and the exposure time is lowest. Over the inner 4' of the field, the detection limit is 2.1 x 10<sup>-4</sup> ct/s, which is equivalent to an X-ray luminosity of about 2 x 10<sup>35</sup> erg/s. Additional information about optical identifications and cross-correlated ROSAT X-ray sources not provided in this HEASARC table is available in the published paper (Tables 4 and 5) and/or the CDS at <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/577/738/">https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/577/738/</a> (table4.dat & table5.dat). This table was created by the HEASARC in October 2004 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/577/738/table2">CDS Catalog J/ApJ/577/738/table2</a>.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/m33chase
- Title:
- M 33 Chandra ACIS Survey (ChASeM33) Final Source Catalog
- Short Name:
- M33CHASE
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the final source catalog of the Chandra ACIS Survey of M33 (ChASeM33). With a total exposure time of 1.4 Ms, ChASeM33 covers ~70% of the D<sub>25</sub> isophote (radial extent ~ 4.0 kpc) of M33 and provides the deepest, most complete, and detailed look at a spiral galaxy in X-rays. The source catalog includes 662 sources, reaches a limiting unabsorbed luminosity of ~2.4 x 10<sup>34</sup> erg s<sup>-1</sup> in the 0.35-8.0 keV energy band, and contains source positions, source net counts, fluxes and significances in several energy bands, and information on source variability. The analysis challenges posed by ChASeM33 and the techniques adopted to address these challenges are discussed. To constrain the nature of the detected X-ray source, hardness ratios were constructed and spectra were fit for 254 sources, follow-up Multiple Mirror Telescope (MMT) spectra of 116 sources were acquired, and cross-correlations with previous X-ray catalogs and other multi-wavelength data were generated. Based on this effort, 183 of the 662 ChASeM33 sources could be identified. Finally, in the reference paper, the luminosity function (LF) for the detected point sources as well as the one for the X-ray binaries (XRBs) in M33 were presented. The LFs in the soft band (0.5-2.0 keV) and the hard band (2.0-8.0 keV) have a limiting luminosity at the 90% completeness limit of 4.0 x 10<sup>34</sup> erg s<sup>-1</sup> and 1.6 x 10<sup>35</sup> erg s<sup>-1</sup> (for an assumed distance D to M33 of 817 kpc), respectively, which is significantly lower than what was reported by previous XRB population studies in galaxies more distant than M33. The resulting distribution is consistent with a dominant population of high-mass XRBs as would be expected for M33. The list of all the Chandra ACIS observations that were used in the construction of this source catalog is given in table 2 of the 2011 reference paper. X-ray source properties, such as counts, dns values, and photon fluxes were computed in the following energy bands: <pre> Band Energy Range (keV) 1 0.5 - 8.0 2 0.5 - 2.0 3 2.0 - 8.0 4 0.35- 8.0 5 0.35- 1.1 6 1.1 - 2.6 7 2.6 - 8.0 8 0.35- 2.0 </pre> This table was created by the HEASARC in April 2011 based on electronic versions of Tables 3, 4, 5, 6, 7 and 9 from the 2011 reference paper which were obtained from the ApJS web site. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/m31cxohrc2
- Title:
- M 31 Chandra HRC X-Ray Source Catalog
- Short Name:
- M31CXOHRC2
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The authors have obtained 17 epochs of Chandra High Resolution Camera (HRC) snapshot images, each covering most of the M31 disk. The data cover a total baseline of ~2.5 yr and contain a mean effective exposure of 17 ks. The authors measured the mean fluxes and long-term light curves for 166 objects detected in these data. At least 25% of the sources show significant variability. The cumulative luminosity function (CLF) of the disk sources is well fitted by a power law with a slope comparable to those observed in typical elliptical galaxies. The CLF of the bulge is a broken power law similar to measurements made by previous surveys. The authors note several sources in the southwestern disk with L<sub>X</sub> > 10<sup>37</sup> ergs s<sup>-1</sup>. They cross-correlate all of their sources with published optical and radio catalogs, as well as new optical data, finding counterpart candidates for 55 sources. In addition, 17 sources are likely X-ray transients. Finally, the frequency of bright X-ray transients in the M31 bulge suggests that the ratio of neutron star to black hole primaries in low-mass X-ray binaries (NS/BH) is 1. The data for this project were originally part of a survey program to look for X-ray transients in M31. Nearly every month from 1999 November to 2001 February, Chandra took HRC-I images of five fields covering most of M31. Observations were then made every few months until 2002 June. The details of the 81 Chandra observations are summarized in Table 1 of the reference paper, which is available in a machine-readable form at <a href="http://cdsarc.u-strasbg.fr/ftp/cats/J_ApJ/609/735/">http://cdsarc.u-strasbg.fr/ftp/cats/J_ApJ/609/735/</a>. The authors combined all the data into three data sets using the task merge_all. One set contained the data for the northern half of the galaxy, another contained the southern half, and the last contained the center. The authors searched for sources in the three data sets using the CIAO task wavdetect. They ran this task searching for sources on four size scales: 1, 2, 4, and 8 pixels. The pixels in the merged images were 1 arcsecond in the central 18 arcmin by 18 arcmin and 2 arcsec outside of this region. By searching on several scales, wavdetect is able to overcome the large changes in the size of the Chandra PSF from about 0.5 arcsec near the center of the field to over 10 arcsec in the outer regions of the field. A total of 166 sources were detected above their 3.5-sigma detection threshold. This table was created by the HEASARC in September 2015 based on the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/609">CDS Catalog J/ApJ/609</a>, 735 file table2.dat . This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/m108cxo
- Title:
- M 108 Chandra X-Ray Compact Source Catalog
- Short Name:
- M108CXO
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains a list of discrete sources found in a 60-ks Chandra ACIS-S observation of the isolated edge-on spiral galaxy NGC 3556 (M108). In the reference paper in which the authors present this table, they also give a multiwavelength analysis of the various discrete X-ray sources and of the diffuse X-ray features. Among 33 discrete X-ray sources detected within the I<sub>B</sub> = 25 mag arcsec<sup>-2</sup> isophotal ellipse of the galaxy, the authors identify a candidate for the galactic nucleus, an ultraluminous X-ray source that might be an accreting intermediate-mass black hole, a possible X-ray binary with a radio counterpart, and two radio-bright giant H II regions. They also detect large amounts of extraplanar diffuse X-ray emission, which extend about 10 kpc radially in the disk and >~4 kpc away from the galactic plane. The diffuse X-ray emission exhibits significant substructures, possibly representing various blown-out superbubbles or chimneys of hot gas heated in massive star-forming regions. This Chandra observation of NGC 3556 (observation ID 2025) was taken between 2001 September 8 and 9 for an exposure of 60 ks. The ACIS-S instrument was at the focal plane of the telescope. This table was created by the HEASARC in August 2015 based on the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/598/969">CDS Catalog J/ApJ/598/969</a> file table2.dat. This is a service provided by NASA HEASARC .
