- ID:
- ivo://nasa.heasarc/m31cxoxray
- Title:
- M 31 Central Region Chandra X-Ray Point Source Catalog
- Short Name:
- Chan/M31
- Date:
- 13 Sep 2024
- 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="ftp://cdsarc.u-strasbg.fr/pub/cats/J/ApJ/577/738/">ftp://cdsarc.u-strasbg.fr/pub/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 .
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- ID:
- ivo://nasa.heasarc/m33chase
- Title:
- M 33 Chandra ACIS Survey (ChASeM33) Final Source Catalog
- Short Name:
- M33CHASE
- Date:
- 13 Sep 2024
- 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:
- 13 Sep 2024
- 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:
- 13 Sep 2024
- 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 CDS Catalog J/ApJ/598/969 file table2.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/m51cxo
- Title:
- M 51 Chandra X-Ray Discrete Source Catalog
- Short Name:
- M51CXO
- Date:
- 13 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the results of two Chandra observations (separated by 1 year) of the population of X-ray sources in the spiral galaxy M 51 (NGC 5194 and NGC 5195). One hundred and thirteen X-ray sources have been detected in an 8.4' x 8.4'(20.4 x 20.4kpc) region, and 84 and 12 of them project within the disks of NGC 5194 and NGC 5195, respectively. Nine and 28 sources have luminosities exceeding 1 x 10^39 erg/s (ultraluminous X-ray sources or ULXs) and 1 x 10^38 erg/s in the 0.5 - 8 keV band, respectively, assuming that they are associated with M 51. The number of ULXs is much higher than found in most normal spiral and elliptical galaxies. Most of the X-ray sources and all seven of the ULXs in NGC 5194 are located in, or close to, a spiral arm, suggesting a connection with recent star formation. The Chandra observations of M 51 were performed on 2000 June 20 and 2001 June 23 with the ACIS instrument. The background was stable in both observations, and effective exposure times of 14.9 and 26.8ks were obtained for the observations in 2000 and 2001, respectively. This table was created by the HEASARC in March 2007 based on CDS catalog J/ApJ/601/735 files table2.dat, table3.dat and table4.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/m81cxo
- Title:
- M 81 Chandra X-Ray Discrete Source Catalog
- Short Name:
- M81CXO
- Date:
- 13 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- A Chandra X-Ray Observatory ACIS-S imaging observation is used to study the population of X-ray sources in the nearby (3.6 Mpc) Sab galaxy M 81 (NGC 3031). A total of 177 sources are detected, with 124 located within the D_25 isophote to a limiting X-ray luminosity of ~ 3 x 10<sup>36</sup> erg/s. Source positions, count rates, luminosities in the 0.3 - 8.0 keV band, limiting optical magnitudes, and potential counterpart identifications are tabulated. Spectral and timing analysis of the 36 brightest sources are reported, including the low-luminosity active galactic nucleus, SN 1993J, and the Einstein-discovered ultraluminous X-ray source X6. The primary X-ray data set is a 49926 s observation of M81 obtained on 2000 May 7 with the Chandra Advanced CCD Imaging Spectrometer (ACIS) spectroscopy array operating in imaging mode. The X-ray data were reprocessed by the Chandra X-ray Center (CXC) on 2001 January 4. These reprocessed data were used in this work. There are no significant differences between the reprocessed data and the originally distributed data analyzed by Tennant et al. (2001ApJ...549L..43T). The observation was taken in faint timed exposure mode at 3.241 s/frame at a focal plane temperature of -120 C. Standard CXC processing has applied aspect corrections and compensated for spacecraft dither. The primary target, SN 1993J, was located near the nominal aimpoint on the back-illuminated (BI) device S3. The nucleus of M81 lies 2.79' from SN 1993J toward the center of S3 in this observation. Accurate positions of these two objects and two G0 stars located on device S2 were used to identify any offset and to determine absolute locations of the remaining Chandra sources as well as objects in other X-ray images and those obtained at other wavelengths. No offset correction was applied to the Chandra X-ray positions. This table was created by the HEASARC in March 2007 based on the CDS table J/ApJS/144/213, files table2.dat and table3.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/m71cxo
- Title:
- M 71 Chandra X-Ray Point Source and Optical/Infrared Counterparts Catalog
- Short Name:
- M71CXO
- Date:
- 13 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The authors observed the nearby, low-density globular cluster M71 (NGC 6838) with the Chandra X-Ray Observatory to study its faint X-ray populations. Five X-ray sources were found inside the cluster core radius, including the known eclipsing binary millisecond pulsar (MSP) PSR J1953+1846A. The X-ray light curve of the source coincident with this MSP shows marginal evidence for periodicity at the binary period of 4.2hr. Its hard X-ray spectrum and luminosity resemble those of other eclipsing binary MSPs in 47 Tuc, suggesting a similar shock origin of the X-ray emission. A further 24 X-ray sources were found within the half-mass radius r<sub>h</sub>, reaching to a limiting luminosity of 1.5 x 10<sup>30</sup> ergs/s (0.3-8 keV). From a radial distribution analysis, the authors find that 18 +/- 6 of these 29 sources are associated with M71, somewhat more than predicted, and that 11 +/- 6 are background sources, both Galactic and extragalactic. M71 appears to have more X-ray sources in the range L<sub>X</sub> = 10<sup>30</sup> - 10<sup>31</sup> ergs/s than expected by extrapolating from other studied clusters using either mass or collision frequency. In their paper, the authors explore the spectra and variability of these sources and describe the results of ground-based optical counterpart searches. The authors obtained a 52.4 ks Chandra observation (ObsID 5434) of M71 (nominal center of cluster at J2000.0 RA and Dec of 19 53 46.1 +18 46 42) on 2004 December 20-21 using the Advanced CCD Imaging Spectrometer (ACIS) in very faint (VF), timed-exposure mode with a 3.141s frame time. They searched for X-ray sources in the observed field by employing techniques described in Tennant (2006, AJ, 132, 1372) which use a circular Gaussian approximation to the point-spread function (PSF). Within twice the M71 half-mass radius (r<sub>h</sub> = 1.65 arcminutes), they set the signal-to-noise threshold (S/N) for detection to 2.0, but also required the number of source counts to be at least 5 times the statistical uncertainty in the local background estimate. The empirical relation derived by Tennant, C<sub>min</sub> = (S/N)<sup>2</sup>/0.81, then implies a point-source sensitivity limit of about 4.9 counts for r<sub>M71</sub> <= 2r<sub>h</sub> and in the energy band 0.3-8.0 keV. Because of the increase in PSF size with off-axis distance and the associated increase in background within a detection cell, for R<sub>M71</sub> > 2r<sub>h</sub> they set the S/N threshold for detection to 2.4 and again required the number of source counts to be at least 5 times the statistical uncertainty in the local background estimate. The point-source sensitivity limit thus rises to about seven counts. This table contains 63 X-ray sources and their optical/infrared counterpart information, if any, for those sources with r<sub>M71</sub> <= 2r_h which are listed in Table 1 of the reference paper: these sources have name prefixes of s01 to s63. It also contains 73 X-ray sources and their optical/infrared counterpart information, if any, for those sources with r<sub>M71</sub> > 2r_h which are listed in Table 2 of the reference paper: these sources have name prefixes of ss01 to ss59 and is01 to is14. Each entry in this table corresponds to an X-ray source if there is no counterpart information or only a single identified counterpart or to a particular X-ray source and counterpart match if there are multiple counterpart identifications. There are thus 165 entries in this HEASARC table corresponding to 136 X-ray sources. This table was created by the HEASARC in March 2011 based on the electronic version of Tables 1 and 2 of the reference paper which were obtained from the CDS (their catalog J/ApJ/687/1019 files table1.dat and table2.dat). Some of the values for the alt_name parameter in the HEASARC's implementation of this table were corrected in April 2018. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/m33cxoxray
- Title:
- M 33 Chandra X-Ray Point Source Catalog
- Short Name:
- ChandraM33
- Date:
- 13 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This database table contains a source list for three Chandra observations of the Local Group galaxy M 33. The observations were centered on the nucleus and on the star-forming region NGC 604. A total of 261 sources were detected in an area of about 0.2 square degrees down to a flux limit of 3 x 10<sup>-16</sup> erg/s/cm<sup>2</sup>, which corresponds to a luminosity of ~2 x 10<sup>34</sup> erg/s at a distance of 840 kpc. The luminosity functions of the X-ray sources observed in M 33 have been constructed and are consistent with those of other star-forming galaxies, taking into account background contamination. In addition, the combination of X-ray color analysis and the existence of "blue" optical counterparts strongly indicates that the X-ray point source population in M 33 consists of young objects. Above 3 x 10<sup>35</sup> erg/s, there are few X-ray sources in the locus of the X-ray hardness ratio diagram that is generally populated by low-mass X-ray binaries. Notice that each of the 261 X-ray sources in the source list has 3 entries in this table, one for each separate Chandra observation, making a total of 783 entries. The Chandra datasets from which this source list was compiled are available by <a href="/db-perl/W3Browse/w3query.pl?tablehead=name%3Dheasarc_chanmaster&sortvar=obsid&bparam_obsid=786%3B+1730%3B+2023">querying CHANMASTER for obsids 786, 1730, and 2023</a>. This table was created by the HEASARC in December 2005 based on the machine-readable version of Table 3 in the above-mentioned Grimm et al. (2005) reference obtained from the ApJ Electronic Edition website. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/m87cxo
- Title:
- M 87 Chandra X-Ray Point Source Catalog
- Short Name:
- M87CXO
- Date:
- 13 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The ACIS instrument on board the Chandra X-Ray Observatory has been used to carry out the first systematic study of low-mass X-ray binaries (LMXBs) in M 87 (NGC 4486), the giant elliptical galaxy near the dynamical center of the Virgo Cluster. These images - with a total exposure time of 154 ks - are the deepest X-ray observations obtained as of 2004 of M 87. The authors identified 174 X-ray point sources, (contained in this Browse table) of which ~ 150 are likely LMXBs. This LMXB catalog was combined with deep F475W and F850LP images taken with ACS on the Hubble Space Telescope (HST) (as part of the ACS Virgo Cluster Survey) to examine the connection between LMXBs and globular clusters in M87. Of the 1688 globular clusters in the authors' catalog, a fraction f<sub>X</sub> = 3.6% +/- 0.5% contain an LMXB. M 87 (NGC 4486) was observed with the Chandra Advanced CCD Imaging Spectrometer (ACIS) for 121 ks on 2002 July 5-6. In this table, only the S3 chip data are used. The data were processed following the CIAO data reduction threads, including a correction for charge transfer inefficiency (CTI). In addition, the authors used 38 ks of archival ACIS observations of M 87 taken on 2000 July 29. These data were processed in a fashion similar to the 2002 July data, except that no CTI correction was possible because the data were telemetered in graded mode. All reductions were carried out with CIAO, version 2.3, coupled with CALDB, version 2.21. In order to combine the event files into a single image for point-source detection, the authors obtained relative offsets by matching the celestial coordinates of two X-ray point sources. The relative offset was ~ 0.5". The total exposure time of the co-added image, excluding four background flares totaling ~ 2.5 ks, was 154 ks. This table was created by the HEASARC in March 2007 based on the CDS table J/ApJ/613/279, file table1.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/m83cxo
- Title:
- M 83 Chandra X-Ray Point Source Catalog
- Short Name:
- M83CXO
- Date:
- 13 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The authors of this table have obtained a series of deep X-ray images of the nearby (4.61 Mpc) galaxy M 83 using Chandra, with a total exposure of 729 ks. Combining the new data with earlier archival observations totaling 61 ks, they find 378 point sources within the D<sub>25</sub> contour of the galaxy. The authors find 80 more sources, mostly background active galactic nuclei (AGNs), outside of the D<sub>25</sub> contour. Of the X-ray sources, 47 have been detected in a new radio survey of M 83 obtained using the Australia Telescope Compact Array (ATCA). Of the X-ray sources, at least 87 seem likely to be supernova remnants (SNRs), based on a combination of their properties in X-rays and at other wavelengths. The authors attempt to classify the point source population of M 83 through a combination of spectral and temporal analysis. As part of this effort, in the reference paper they carry out an initial spectral analysis of the 29 brightest X-ray sources. The soft X-ray sources in the disk, many of which are SNRs, are associated with the spiral arms, while the harder X-ray sources, mostly X-ray binaries (XRBs), do not appear to be. After eliminating AGNs, foreground stars, and identified SNRs from the sample, the authors construct the cumulative luminosity function (CLF) of XRBs brighter than 8 x 10<sup>35</sup> erg s<sup>-1</sup>. Despite M 83's relatively high star formation rate, the CLF indicates that most of the XRBs in the disk are low mass X-ray binaries (XRBs). The X-ray observations of M 83 in this survey were all carried out with the ACIS-S in order to maximize the sensitivity to soft X-ray sources, such as SNRs, and to diffuse emission. The nucleus of M 83 was centered in the field of the back-illuminated S3 chip to provide reasonably uniform coverage of M 83. In addition to the S3 chip, data were also obtained from chips S1, S2, S4, I2, and I3. All of the observations were made in the "very faint" mode to optimize background subtraction. Observations were spaced over a period of one year from 2010 December to 2011 December, as indicated in Table 1 of the reference paper. The only difference among observations was the roll orientation of the spacecraft and the differing exposure times. All of the observations were nominal, and yielded a total of 729 ks of useful data. In order to maximize their sensitivity and more importantly to improve their ability to identify time variable sources, the authors included in their analysis earlier Chandra observations of M 83 in 2000 and 2001 totaling 61 ks which were obtained by G. Rieke (Prop ID. 1600489) and by A. Prestwich (Prop ID. 267005758). These data were obtained in a very similar manner to that of the present survey, and increased the total exposure to 790 ks. The authors used ACIS EXTRACT (AE) to derive net count rates from the sources in various energy bands: 0.35 - 8.0 keV (total or T), 0.35 - 1.1 keV (soft or S), 1.1 - 2.6 keV (medium or M), 2.6 - 8.0 keV (hard or H), 0.5 - 2.0 keV ("normal" soft band) and 2.0 - 8.0 keV ("normal" hard band). Their choice of these bands was based on a variety of overlapping goals. The broad 0.35 - 8.0 keV band samples the full energy range accessible to Chandra observations. The three bands S, M and H provide energy ranges intended to classify sources on the basis of their hardness ratios. The boundary at 1.1 keV, in particular, is just above the region containing strong features due to Ne and Fe seen in the spectra of most SNRs. The 0.5 - 2.0 keV and 2.0 - 8.0 keV bands are needed because number counts of active galactic nuclei (AGNs) and of X-ray binary populations are normally carried out in these bands and because the 0.5 - 2.0 keV band, encompassing the peak of the response curve, provides better statistics for some purposes than S+M. The AE count rates were used to establish which of the sources in the candidate list were statistically valid. The authors retained any source that had a probability-of-no-source < 5 x 10<sup>-6</sup> in any one of these bands in the total data set. For their final run of AE, their list of source candidates had 847 potential sources. Of those, they find a total of 458 valid point sources, whose properties are listed in this table. Of the 458 point sources, 378 are located within the area defined by the D<sub>25</sub> ellipse of the galaxy (which the authors take to have a major axis diameter of 12.9 arcminutes), and the remaining 80 are outside this region. There were 43 sources in the nuclear region (defined to be any source within a projected radius of 0.5 kpc from the optical nucleus). This table was created by the HEASARC in July 2014 based on electronic versions of Tables 3, 4 and 5 from the reference paper which were obtained from the ApJS website. This is a service provided by NASA HEASARC .