- ID:
- ivo://nasa.heasarc/ngc1333cxo
- Title:
- NGC 1333 Chandra X-Ray Point Source Catalog
- Short Name:
- NGC1333CXO
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- NGC 1333, a highly active star formation region within the Perseus molecular cloud complex, has been observed on 2000 July 12.96 - 13.48 with the ACIS-I detector on board the Chandra X-Ray Observatory. The aim point of the array was 3 29 06.1, +31 19 38 (J2000,0 RA and Dec), the satellite roll angle was 95.7 degrees, and the effective exposure time after removing time intervals contaminated by background flaring was 37.8 ks. In this image with a sensitivity limit in luminosity of ~10<sup>28</sup> erg/s for X-ray sources at the 318 pc distance of NGC 1333, 127 X-ray sources were detected, most with sub-arcsecond positional accuracy. While 32 of these sources appear to be foreground stars and extragalactic background objects, 95 X-ray sources are identified with known cluster members. The X-ray luminosity function of the discovered young stellar object (YSO) population spans a range of log L<sub>X</sub> ~= 28.0 - 31.5 erg s<sup>-1</sup> in the 0.5 - 8 keV band, and the absorption column densities range from log N<sub>H</sub> ~=20 to 23 cm<sup>-2</sup>. Most of the sources have plasma temperatures between 0.6 and 3 keV, but a few sources show higher temperatures up to ~7 keV. Comparison with K-band source counts indicates that all of the known cluster members with K < 12 and about half of the members with K > 12 were detected. (K ~= 11, the peak of the K-band luminosity function, corresponds to 0.2 - 0.4 M_solar stars for a cluster age of ~1 Myr). Seven of the 20 known YSOs in NGC 1333 which are producing jets or molecular outflows were detected, as well as one deeply embedded object without outflows. No evident difference in X-ray emission of young stars with and without outflows is found. This present table contains X-ray, optical and near-infrared information on the 109 X-ray sources that were detected above a source significance threshold of 1 x 10<sup>-6</sup> in any of 3 energy bands: soft: 0.5 - 2.0 keV, hard: 2.0 - 8.0 keV, or full: 0.5 - 8.0 keV, excluding 8 sources that were deemed to be spurious on visual examination of the images. The faintest on-axis source emerging from the wavelet detection procedure has 5 extracted counts, corresponding to a source of log L<sub>X</sub> ~ 28.0 in the total (0.5 - 8.0 keV) band for a source with negligible interstellar absorption (A<sub>V</sub> ~ 1) and a typical source spectrum of a kT ~ 1 keV thermal plasma. This limit increases to 28.6 (29.3) if the absorption is increased to A<sub>V</sub> ~ 5 (10). The sensitivity decreases by a factor of 4 at the edge of the field compared to the central regions. 80 of the significant 109 sources (73%) have counterparts in a non-X-ray band. This table does not include 18 tentative X-ray sources listed in Table 3 of the reference paper that were found by the authors by searching for concentrations of photons spatially coincident with known sources from near-IR, mm/sub-mm, and radio catalogs of this region which did not reach the detection significance given above. Most of these tentative sources are believed to be real sources. This table was created by the HEASARC in March 2007 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/575/354">CDS catalog J/ApJ/575/354</a> files table1.dat and table2.dat. This is a service provided by NASA HEASARC .
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- ID:
- ivo://nasa.heasarc/ngc6357cxo
- Title:
- NGC 6357 Chandra X-Ray Point Source Catalog
- Short Name:
- NGC6357CXO
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This contains some of the results from the first high spatial resolution X-ray study of the massive star-forming region NGC 6357, which were obtained in a 38 ks Chandra/ACIS observation. Inside the brightest constituent of this large H II region complex is the massive open cluster Pismis 24. It contains two of the brightest and bluest stars known, yet remains poorly studied; only a handful of optically bright stellar members have been identified. The authors have investigated the cluster extent and initial mass function and detected ~800 X-ray sources with a limiting sensitivity of ~ 10<sup>30</sup> erg s<sup>-1</sup>: this provides the first reliable probe of the rich intermediate-mass and low-mass population of this massive cluster, increasing the number of known members from optical studies by a factor of ~ 50. The high-luminosity end (log L[2-8 keV] >= 30.3 erg s<sup>-1</sup>) of the observed X-ray luminosity function in NGC 6357 is clearly consistent with a power-law relation as seen in the Orion Nebula Cluster and Cepheus B, yielding the first estimate of NGC 6357's total cluster population, a few times the known Orion population. The long-standing L<sub>X</sub> ~ 10<sup>-7</sup> L<sub>bol</sub> correlation for O stars is confirmed. Twenty-four candidate O stars and one possible new obscured massive YSO or Wolf-Rayet star are presented. Many cluster members are estimated to be intermediate-mass stars from available infrared photometry (assuming an age of ~ 1 Myr), but only a few exhibit K-band excess. The authors report the first detection of X-ray emission from an evaporating gaseous globule at the tip of a molecular pillar; this source is likely a B0-B2 protostar. NGC 6357 was observed on 2004 July 9 with the Imaging Array of the Advanced CCD Imaging Spectrometer (ACIS-I) on board Chandra. Four front-illuminated (FI) CCDs form the ACIS-I, which covers a field of view (FOV) of ~ 17 by 17 arcminutes. The observation was made in the standard Timed Exposure, Very Faint mode, with 3.2 s integration time and 5 pixel by 5 pixel event islands. The total exposure time was 38 ks and the satellite roll angle was 289 degrees. The aim point was centered on the O3 If star Pis 24-1, the heart of the OB association Pismis 24. The Chandra observation ID is 4477. Data reduction started with filtering the Level 1 event list processed by the Chandra X-ray Center pipeline to recover an improved Level 2 event list. To improve absolute astrometry, X-ray positions of ACIS-I sources were obtained by running the wavdetect wavelet-based source detection algorithm within the Chandra Interactive Analysis of Observations (CIAO) package on the original Level 2 event list, using only the central 8 by 8 arcminutes of the field. The resulting X-ray sources were matched to the 2MASS point source catalog. The authors calculated the position offsets between 277 X-ray sources and their NIR counterparts and applied an offset of +0.02" in right ascension (R.A.) and -0.33" in declination to the X-ray coordinates. From an initial list of 910 potential X-ray sources, the authors rejected sources with a P<sub>B</sub> > 1% likelihood of being a background fluctuation. The trimmed source list includes 779 sources, with full-band (0.5 - 8.0 keV) net (background-subtracted) counts ranging from 1.7 to 1837 counts. The 779 valid sources were purposely divided by the authors into two lists: the 665 sources with P<sub>B</sub> < 0.1% make up the primary source list of highly reliable sources (Table 1 in the reference paper; sources with source_type = 'M' in this table), and the remaining 114 sources with P<sub>B</sub> >= 0.1% likelihood of being spurious background fluctuations were listed as tentative sources in Table 2 of the reference paper (source_type = 'T' in this table). The authors believe that most of these tentative sources are likely real detections. This table was created by the HEASARC in October 2007 based on the merger of the electronic versions of Tables 1 (Main Source Catalog) and 2 (Tentative Sources which were obtained from the ApJ website. To help distinguish from which original table entries in this Browse table come from, the HEASARC has created a parameter called source_type which is set to 'M' for sources from Table 1 and to 'T' for sources from Table 2. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/ngc6231cx2
- Title:
- NGC 6231 Chandra X-Ray Point Source Catalog 2
- Short Name:
- NGC6231CX2
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- NGC 6231 is a young cluster (age ~2-7 Myr) dominating the Sco OB1 association (distance ~1.59 kpc) with ~100 O and B stars and a large pre-main-sequence stellar population. The authors combine a reanalysis of archival Chandra X-ray data with multi-epoch near-infrared (NIR) photometry from the VISTA Variables in the Via Lactea (VVV) survey and published optical catalogs to obtain a catalog of 2148 probable cluster members. This catalog is 70% larger than previous censuses of probable cluster members in NGC 6231. It includes many low-mass stars detected in the NIR but not in the optical and some B stars without previously noted X-ray counterparts. In addition, the authors identify 295 NIR variables, about half of which are expected to be pre-main-sequence stars. With the more complete sample, they estimate a total population in the Chandra field of 5700-7500 cluster members down to 0.08 M<sub>sun</sub> (assuming a universal initial mass function) with a completeness limit at 0.5 M<sub>sun</sub>. A decrease in stellar X-ray luminosities is noted relative to other younger clusters. However, within the cluster, there is little variation in the distribution of X-ray luminosities for ages less than 5 Myr. The X-ray spectral hardness for B stars may be useful for distinguishing between early-B stars with X-rays generated in stellar winds and B-star systems with X-rays from a pre-main-sequence companion (>35% of B stars). A small fraction of catalog members have unusually high X-ray median energies or reddened NIR colors, which might be explained by absorption from thick or edge-on disks or being background field stars. This work makes use of some basic cluster properties available from the literature. Summaries of older studies are provided by Sana et al. (2006, J/A+A/454/1047), available in <a href="/W3Browse/xmm-newton/ngc6231xmm.html">NGC6231XMM</a>, and Reipurth (2008hsf2.book.....R). Expanded catalogs of cluster members have been provided by Sung et al. (2013, J/AJ/145/37) and Damiani et al. 2016, J/A+A/596/A82 (DMS2016), available at <a href="/W3Browse/chandra/ngc6231cxo.html">NGC6231CXO</a>. Chandra X-ray observations were made using the imaging array on the Advanced CCD Imaging Spectrometer (ACIS-I; Garmire et al. 2003SPIE.4851...28G). This instrument is an array of four CCD detectors that subtends 17'x17'. The target was observed in 2005 July (Sequence 200307; PI: S. Murray) in two observations (ObsID 5372 and 6291), and the data were retrieved from the Chandra Data Archive. The NIR ZYJHK<sub>s</sub> data were obtained from the VVV survey (Minniti et al. 2010NewA...15..433M; Saito et al. 2012, Cat. II/337). VVV is a multi-epoch NIR survey that covers both the Galactic bulge and an adjacent Galactic disk region and was carried out using the 4.1 m VISTA telescope on Cerro Paranal. The VVV data were taken with the VISTA Infrared CAMera (VIRCAM; Dalton et al. 2006SPIE.6269E..0XD), a 4x4 array of Raytheon VIRGO 2048x2048 20 micron pixel detectors with a pixel scale of 0.34". In addition to the VVV photometry, public optical or infrared catalogs are available from surveys and publications. We have included VPHAS+ photometry (Drew et al. 2014, J/MNRAS/440/2036), UBVRI (Johnson-Cousins system) and H-alpha photometry from Sung et al. (2013, J/AJ/145/37), and Spitzer/IRAC photometry from the GLIMPSE survey (Benjamin et al. 2003, Cat. II/293). This table was created by the HEASARC in October 2020 based upon the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/AJ/154/87">CDS Catalog J/AJ/154/87</a> file table1.dat, table3.dat, and table5.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/ngc6530cxo
- Title:
- NGC 6530 Chandra X-Ray Point Source Catalog
- Short Name:
- NGC6530CXO
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- In a deep 60 ks Chandra ACIS-I X-ray observation of the very young (~ 1.5 - 2.0 Myr) cluster NGC 6530 on 2001 Jun 18-19, the authors have detected 884 X-ray point sources and argue that a very large fraction of them (90%-95%) must be pre-main-sequence (PMS) cluster members, mostly low-mass stars. This is a significant enlargement of the known NGC 6530 stellar population with respect to previous optical studies, including H-alpha surveys. They identify 220 X-ray sources with catalogued stars down to V = 17, while most unidentified sources have fainter counterparts. Moreover, they find an infrared counterpart in the 2MASS (CDS. No. <II/246>) Catalog for 731 X-ray sources. The optically identified cluster X-ray sources are found in a band in the H-R diagram above the main sequence, in the locus of 0.5 - 1.5 Myr PMS stars, with masses down to 0.5 - 1.5 solar masses (M_sun). The pointing direction for the Chandra observation was the NGC 6530 cluster center at RA = 18^h 04^m 24.38^s, Dec = -24^o 21' 05.8" (J2000.0). The PWDetect algorithm found 884 X-ray point sources in the ACIS-I image above a detection significance threshold chosen to ensure only 1 spurious detection on the average. The Sung et al. (2000, AJ, 120, 333; <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/AJ/120/333">CDS Cat. <J/AJ/120/333></a>) = SCB Catalog of optical objects against which the X-ray point source list was compared doed not cover the easternmost 2.25' of the ACIS FOV (RAs later than 18^h 04^m 52^s), notice, which comprises about 13% of the ACIS FOV. There are 46 detected X-ray sources (5.2% of the total) in the area not covered by the SCB Catalog. A matching distance of 4 times the X-ray error radius or 2.0" (whichever is greater) was used to identify optical counterparts to the X-ray sources, after a systematic shift between the X-ray and optical positions of -0.4" and 1.84" in RA and declination, respectively, was applied. The authors estimate that as many as 28 of their 220 optical identifications may be spurious, preferentially those in the outer parts of the FOV where the positional uncertainties are larger. There are 8792 'good' 2MASS sources in the ACIS FOV. A matching distance of 4 times the X-ray error radius or 1.5" (whichever is greater) was used to identify 2MASS counterparts to the X-ray sources, after systematic corrections of 0.3" and 1.75" in RA and declination, respectively, were applied to the 'raw' X-ray positions. There are 13 cases where there are two possible IR counterparts to a single X-ray source, and 2 cases where there are three possible IR Counterparts to a single X-ray source. (Notice that, in such cases, this table contains multiple entries, one for each counterpart, and hence there are 901 entries compared to 884 X-ray sources.) The authors conclude that the plausible number of spurious X-ray-2MASS identifications is between 30 and 50. Overall, there remain 146 X-ray sources with no optical or IR identification. This table was created by the HEASARC in December 2006 based on CDS table J/ApJ/608/781, the file table1.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/ngc5866cxo
- Title:
- NGC 5866 Chandra X-Ray Point Source Catalog
- Short Name:
- NGC5866CXO
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- S0 galaxies are often thought to be passively evolved from spirals after star formation is quenched. To explore what is actually occurring in such galaxies, the authors conducted a multi-wavelength case study of NGC 5866 - a nearby edge-on S0 galaxy in a relatively isolated environment. This study shows strong evidence for dynamic activities in the interstellar medium, which are most likely driven by supernova explosions in the galactic disk and bulge. Understanding these activities can have strong implications for studying the evolution of such galaxies. The authors utilized Chandra, Hubble Space Telescope, and Spitzer data as well as ground-based observations to characterize the content, structure, and physical state of the medium and its interplay with the stellar component in NGC 5866. These reveal the presence of diffuse X-ray-emitting hot gas, which extends as far as 3.5 kpc away from the galactic plane and can be heated easily by Type Ia SNe in the bulge. The Chandra/ACIS observation of NGC 5866 was taken on 2002 November 14. The authors reprocessed the archived data for their study. See Figure 1 in the reference paper for the Chandra/ACIS-S image of NGC 5866 in the 0.3-7 keV band. This table contains the detected X-ray point sources listed in table 2 of this paper. This table was created by the HEASARC in May 2018 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/706/693">CDS Catalog J/ApJ/706/693</a> file table2.dat, the list of detected X-ray sources in the Chandra observation of NGC 5866. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/ngc1399cxo
- Title:
- NGC 1399 Chandra X-Ray Source Catalog
- Short Name:
- NGC1399CXO
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains results from a wide-field study of the globular cluster (GC)/low-mass X-ray binary (LMXB) connection in the giant elliptical NGC 1399. The large field of view of the Advanced Camera for Surveys/WFC, combined with the high resolution of the Hubble Space Telescope and Chandra, allow the authors to constrain the LMXB formation scenarios in elliptical galaxies. They confirm that NGC 1399 has the highest LMXB fraction in GCs of all nearby elliptical galaxies studied so far, even though the exact value depends on galactocentric distance due to the interplay of a differential GC versus galaxy light distribution and the GC color dependence. In fact, LMXBs are preferentially hosted by bright, red GCs out to > 5 R<sub>eff</sub> of the galaxy light. The finding that GCs hosting LMXBs follow the radial distribution of their parent GC population argues against the hypothesis that the external dynamical influence of the galaxy affects the LMXB formation in GCs. On the other hand, field-LMXBs closely match the host galaxy light, thus indicating that they are originally formed in situ and not inside GCs. The authors measure GC structural parameters, finding that the LMXB formation likelihood is influenced independently by mass, metallicity, and GC structural parameters. In particular, the GC central density plays a major role in predicting which GCs host accreting binaries. Finally, this analysis shows that LMXBs in GCs are marginally brighter than those in the field, and in particular the only color-confirmed GC with L<sub>X</sub> > 10<sup>39</sup> erg/s shows no variability, which may indicate a superposition of multiple LMXBs in these systems. The optical data were taken with the ACS on board the HST (GO-10129), in the F606W filter. A detailed description of the HST data and source catalogs are given in Puzia T.H. et al. 2011, in preparation. The X-ray data were retrieved from the Chandra public archive (CXC). The authors selected observations 319 (ACIS-S; 2000 Jan 18) and 1472 (ACIS-I; 2003 May 26). This table contains the list of 230 X-ray sources detected in the overlap region common to Chandra ACIS-I, Chandra ACIS-S and HST ACS observation (see Fig 1 of the reference paper). Details of the X-ray source detection methodology are given in Section 2.2 of the reference paper. This table was created by the HEASARC in January 2013 based on the CDS Catalog J/ApJ/736/90 file table3.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/ngc6357oid
- Title:
- NGC 6357/Pismis 24 Chandra Point Source Optical/IR Identifications Catalog
- Short Name:
- NGC6357OID
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- Circumstellar disks are expected to evolve quickly in massive young clusters harboring many OB-type stars. Two processes have been proposed to drive the disk evolution in such cruel environments: (1) gravitational interaction between circumstellar disks and nearby passing stars (stellar encounters), and (2) photoevaporation by UV photons from massive stars. The relative importance of both mechanisms is not well understood. Studies of massive young star clusters can provide observational constraints on the processes of driving disk evolution. The authors investigate the properties of young stars and their disks in the NGC 6357 complex, concentrating on the most massive star cluster within the complex: Pismis 24. They use infrared data from the 2MASS and Spitzer GLIMPSE surveys, complemented with their own deep Spitzer imaging of the central regions of Pismis 24, in combination with X-ray data to search for young stellar objects (YSOs) in the NGC 6357 complex. The infrared data constrain the disk presence and are complemented by optical photometric and spectroscopic observations, obtained with VLT/VIMOS, that constrain the properties of the central stars. For those stars with reliable spectral types, they combine spectra and photometry to estimate the masses and ages. For cluster members without reliable spectral types, they obtain the mass and age probability distributions from R and I-band photometry, assuming these stars have the same extinction distribution as those in the "spectroscopic" sample. The authors compare the disk properties in the Pismis 24 cluster with those in other clusters/star-forming regions employing infrared color-color diagrams. The authors discover two new young clusters in the NGC 6357 complex. They give a revised distance estimate for Pismis 24 of 1.7 +/- 0.2 kpc. They also find that the massive star Pis 24-18 is a binary system, with the secondary being the main X-ray source of the pair. The authors provide photometry in 9 bands between 0.55 and 8 micron (µm) for the members of the Pismis 24 cluster. They derive the cluster mass function and find that up to the completeness limit at low masses it agrees well with the initial mass function of the Trapezium cluster. They derive a median age of 1 Myr for the Pismis 24 cluster members. The R-band observations were performed on 2008 April 1 and 6, and the I-band observations were done on 2008 May 1, both using the VIMOS instrument on the VLT. The near-IR photometry in the J, H and K<sub>s</sub> bands were taken from the 2MASS. The mid-IR photometry at 3.6, 4.5, 5.8 and 8.0 um were obtained withe the Spitzer IRAC camera, both from the GLIMPSE I survey and from deep observations of the central Pismis 24 region carried out by the authors on 2006 September 29. The X-ray observations were made by the Chandra ACIS-I instrument and previously published by Wang et al. (2007, ApJS, 168, 100: the HEASARC NGC6357CXO table). The X-ray sources were matched to sources detected in the VIMOS R and I bands based on positional coincidence, using a 1.5 arcseconds tolerance. The accuracy of the optical and X-ray positions was 0.6 and 1.0 arcseconds, respectively. Given the high space density of sources in the central regions of Pismis 24, there may be a substantial number (up to 1/6 of the sources) of "false positives", according to the authors. This table contains the list of 643 optical/IR counterparts to the Chandra X-ray sources found by Wang et al. (2007) which were identified by the present authors: for 136 of the 779 X-ray sources, no counterparts were found. This table was created by the HEASARC in March 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/539/A119">CDS Catalog J/A+A/539/A119</a> files table1.dat and table3.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/ngc2244cxo
- Title:
- NGC 2244/Rosette Nebula Chandra X-Ray Point Source Catalog
- Short Name:
- NGC2244CXO
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the point source catalog based on the first high spatial resolution X-ray study of NGC 2244, the 2 Myr old stellar cluster in the Rosette Nebula, using Chandra. Over 900 X-ray sources are detected within 20 arcminutes of the cluster central position (J2000.0 RA and Dec of 6 31 59.9, +4 55 36); 77% of these X-ray sources have optical or FLAMINGOS NIR stellar counterparts and are mostly previously uncataloged young cluster members. The X-ray-selected population is estimated to be nearly complete between 0.5 and 3 M<sub>solar</sub>. A number of further results emerge from the analysis: (1) The X-ray luminosity function (XLF) and the associated K-band LF indicate a normal Salpeter IMF for NGC 2244. This is inconsistent with the top-heavy IMF reported from earlier optical studies that lacked a good census of < 4 M<sub>solar</sub> stars. By comparing the NGC 2244 and Orion Nebula Cluster XLFs, the authors estimate a total population of ~2000 stars in NGC 2244. (2) The spatial distribution of X-ray stars is strongly concentrated around the central O5 star, HD 46150. The other early O star, HD 46223, has few companions. The cluster's stellar radial density profile shows two distinctive structures: a power-law cusp around HD 46150 that extends to ~0.7 pc, surrounded by an isothermal sphere extending out to 4 pc with core radius 1.2 pc. This double structure, combined with the absence of mass segregation, indicates that this 2 Myr old cluster is not in dynamical equilibrium. (3) The fraction of X-ray-selected cluster members with K-band excesses caused by inner protoplanetary disks is 6%, slightly lower than the 10% disk fraction estimated from the FLAMINGOS study based on the NIR-selected sample. (4) X-ray luminosities for 24 stars earlier than B4 confirm the long-standing log (L<sub>X</sub>/L<sub>bol</sub>) ~ -7 relation. The Rosette OB X-ray spectra are soft and consistent with the standard model of small-scale shocks in the inner wind of a single massive star. This table was created by the HEASARC in July 2008 based on electronic versions of Tables 2, 3, 4, 5 and 6 of the reference paper which were obtained from the electronic ApJ web site. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/narcscat
- Title:
- NormaArmRegionChandraSurveyPoint&ExtendedSourceCatalog
- Short Name:
- NARCSCAT
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the catalog of 1,415 X-ray sources identified in the Norma Arm Region Chandra Survey (NARCS), which covers a 2 degree x 0.8 degree region in the direction of the Norma spiral arm to a depth of ~ 20 ks. Of these sources, 1,130 are point-like sources detected with >= 3-sigma confidence in at least one of three energy bands (0.5 - 10, 0.5 - 2, and 2 - 10 keV), five have extended emission, and the remainder are detected at low significance. Since most sources have too few counts to permit individual classification, they are divided into five spectral groups defined by their quantile properties. The authors analyze stacked spectra of X-ray sources within each group, in conjunction with their fluxes, variability, and infrared counterparts, to identify the dominant populations in this survey. They find that ~ 50% of their sources are foreground sources located within 1 - 2 kpc, which is consistent with expectations from previous surveys. Approximately 20% of sources are likely located in the proximity of the Scutum-Crux and near Norma arm, while 30% are more distant, in the proximity of the far Norma arm or beyond. The authors argue that a mixture of magnetic and non-magnetic cataclysmic variables dominates the Scutum-Crux and near Norma arms, while intermediate polars and high-mass stars (isolated or in binaries) dominate the far Norma arm. In the paper, they also present the cumulative number count distribution for sources in this survey that are detected in the hard energy band. A population of very hard sources in the vicinity of the far Norma arm and active galactic nuclei dominate the hard X-ray emission down to f<sub>X</sub> ~ 10<sup>-14</sup> erg cm<sup>-2</sup> s<sup>-1</sup>, but the distribution curve flattens at fainter fluxes. The authors find good agreement between the observed distribution and predictions based on other surveys. Chandra ACIS-I observations were performed in faint mode of a 2 degree by 0.8 degree region of the Norma spiral arm in 2011 June. This field was subdivided into 27 pointings; Table 1 in the reference paper reports their coordinates and exposure times and Figure 1 (op. cit.) is a mosaic image of the survey. The observing strategy was to cover a wide area with relatively uniform flux sensitivity and good spatial resolution; therefore, the authors chose field centers spaced by 12 arcminutes, which provided roughly 70 arcminute<sup>2</sup> of overlap on the outskirts of adjacent observations such that the additional exposure time in these overlapping regions partly made up for the worsening point-spread function (PSF) at large off-axis angles. This table was created by the HEASARC in March 2015 based on electronic versions of Tables 3, 4 and 5 from the reference paper which were obtained from the ApJ web site. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/omc2p3cxo
- Title:
- OMC-2 and OMC-3 Chandra X-Ray Point Source Catalog
- Short Name:
- OMC2P3CXO
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The OMC-2 and OMC-3 Chandra X-Ray Point Source Catalog contains the results of the Chandra X-ray observation of Orion Molecular Clouds 2 and 3 (OMC-2 and OMC-3). A deep exposure of ~100 ks detects ~400 X-ray sources in the field of view (FOV) of the ACIS array, providing one of the largest X-ray catalogs in a star-forming region as of the date that this was published (February 2002). Coherent studies of the source detection, time variability, and energy spectra were performed. The authors classified the X-ray sources into Class I, Class II, and Class III+MS types based on the J-, H-, and K-band colors of their near-infrared counterparts, and discussed the X-ray properties (temperature, absorption, and time variability) along these evolutionary phases. The results of the X-ray imaging analysis and a correlation with the 2MASS Catalog are given for all the detected X-ray sources. Notice that the sources '[TKT2002] I1' - '[TKT2002] I354' and '[TKT2002] S1' - '[TKT2002] S11' were detected in the total-band image (0.5 - 8.0 keV) images of the ACIS-I and the ACIS-S2 CCDs, respectively, but that source '[TKT2002] I355' - '[TKT2002] I369' and '[TKT2002] S12' - '[TKT2002] S13' were detected only in the hard-band (2.0 - 8.0 keV) images of the ACIS-I and the ACIS-S2 CCDs, and '[TKT2002] I370' - '[TKT2002] I385' were detected only in the soft-band (0.5 - 2.0 keV) image of the ACIS-I. No new source was detected in the soft band image of the ACIS-S2 CCD. This table was created by the HEASARC in January 2007 based on CDS table J/ApJ/566/974, files table1.dat and table2.dat. This is a service provided by NASA HEASARC .