- ID:
- ivo://nasa.heasarc/ngc1291cxo
- Title:
- NGC 1291 Chandra X-Ray Point Source Catalog
- Short Name:
- NGC1291CXO
- Date:
- 13 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains some of the results from a study of the X-ray binary (XRB) populations in the bulge and ring regions of the ring galaxy NGC 1291. Utilizing the four available Chandra observations totaling an effective exposure of 179 ks, the authors detect 169 X-ray point sources in the galaxy in the full band (0.3 - 8.0 keV) with a false-positive probability threshold of 10<sup>-6</sup> (implying approximately 2 false detections given the size of the image). Of these sources, 75 are in the bulge and 71 are in the ring. The authors report photometric properties of these sources in a point-source catalog. There are ~ 40% of the bulge sources and ~ 25% of the ring sources showing > 3-sigma long-term variability in their X-ray count rate. The X-ray colors suggest that a significant fraction of the bulge (~ 75%) and ring (~ 65%) sources are likely low-mass X-ray binaries (LMXBs). The spectra of the nuclear source indicate that it is a low-luminosity active galactic nucleus (AGN) with moderate obscuration; spectral variability is observed between individual observations. The authors construct 0.3-8.0 keV X-ray luminosity functions (XLFs) for the bulge and ring XRB populations, taking into account the detection incompleteness and background AGN contamination. They reach 90% completeness limits of ~ 1.5 x 10<sup>37</sup> and ~ 2.2 x 10<sup>37</sup> erg s<sup>-1</sup> for the bulge and ring populations, respectively. Both XLFs can be fit with a broken power-law model, and the shapes are consistent with those expected for populations dominated by LMXBs. In the paper, the authors perform detailed population synthesis modeling of the XRB populations in NGC 1291, which suggests that the observed combined XLF is dominated by an old LMXB population. They compare the bulge and ring XRB populations, and argue that the ring XRBs are associated with a younger stellar population than the bulge sources, based on the relative overdensity of X-ray sources in the ring, the generally harder X-ray color of the ring sources, the overabundance of luminous sources in the combined XLF, and the flatter shape of the ring XLF. This table was created by the HEASARC in May 2012 based on an electronic version of Table 2 from the reference paper obtained from the ApJ website. This is a service provided by NASA HEASARC .
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- ID:
- ivo://nasa.heasarc/ngc6334cxo
- Title:
- NGC 6334 Chandra X-Ray Point Source Catalog
- Short Name:
- NGC6334CXO
- Date:
- 13 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The full stellar population of NGC 6334, one of the most spectacular regions of massive star formation in the nearby Galaxy, has not been well sampled in past studies. The authors have analyzed a mosaic of two Chandra X-ray Observatory images of the region using sensitive data analysis methods, giving a list of 1607 faint X-ray sources with arcsecond positions and approximate line-of-sight absorption. About 95% of these are expected to be cluster members, most lower mass pre-main-sequence stars. Extrapolating to low X-ray levels, the total stellar population is estimated to be 20,000 - 30,000 pre-main-sequence stars. The X-ray sources show a complicated spatial pattern with ~10 distinct star clusters. The heavily obscured clusters are mostly associated with previously known far-infrared sources and radio H II regions. The lightly obscured clusters are mostly newly identified in the X-ray images. Dozens of likely OB stars are found, both in clusters and dispersed throughout the region, suggesting that star formation in the complex has proceeded over millions of years. A number of extraordinarily heavily absorbed X-ray sources are associated with the active regions of star formation. This table was created by the HEASARC in August 2009 based on the electronic version of table 1 from the above reference which were obtained from the AJ web site. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/ngc300cxo
- Title:
- NGC 300 Chandra X-Ray Point Source Catalog
- Short Name:
- NGC300CXO
- Date:
- 13 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the source catalog from a new Chandra ACIS-I observation of the nearby (2.0 Mpc) SA(s)d spiral galaxy NGC 300 which was obtained as part of the Chandra Local Volume Survey (CLVS). This 63-ks exposure covers ~88% of the D<sub>25</sub> isophote (R ~ 6.3 kpc) and yields a catalog of 95 X-ray point sources detected at high significance down to a limiting unabsorbed 0.35-8 keV luminosity of ~ 10<sup>36</sup> erg/s. Sources were cross-correlated with a previous XMM-Newton catalog, and the authors find 75 "X-ray transient candidate" sources that were detected by one observatory, but not the other. They derive an X-ray scale length of 1.7 +/- 0.2 kpc and a recent star formation rate of 0.12 M<sub>sun</sub>/yr in excellent agreement with optical observations. Deep, multi-color imaging from the Hubble Space Telescope, covering ~ 32% of this Chandra field, was used to search for optical counterparts to the X-ray sources, and the authors have developed a new source classification scheme to determine which sources are likely X-ray binaries, supernova remnants, and background active galactic nucleus candidates. In the reference paper, the authors present the X-ray luminosity functions (XLFs) at different X-ray energies, and find the total NGC 300 X-ray point-source population to be consistent with other late-type galaxies hosting young stellar populations (<~ 50 Myr). They find that the XLF of sources associated with older stellar populations has a steeper slope than the XLF of X-ray sources coinciding with young stellar populations, consistent with theoretical predictions. NGC 300 was observed on 2010 September 25 for 63 ks using ACIS-I during the Chandra X-Ray Observatory Cycle 12, observation ID 12238. The source detection strategy that was used is described in Section 2.3 of the reference paper. ACIS-Extract (AE) was run a final time on the source list that was produces after an initial run of wavdetect followed by several iterations of AE, and the Poisson probability of not being a source (pns) value was computed in each of the following nine energy bands: 0.5 - 8.0, 0.5 - 2.0, 2.0 - 8.0, 0.5 - 1.0, 1.0 - 2.0, 2.0 - 4.0, 4.0 - 8.0, 0.35 - 1.0 and 0.35 - 8.0 keV. To be included in the final NGC 300 catalog, a source was required to have a pns value less than 4 x 10<sup>-6</sup> in any of the nine energy bands; if only the 0.35 - 8 keV band were considered, ~4% of significant sources would have been lost. The final CLVS source catalog for NGC 300 contains 95 sources. This table was initially created by the HEASARC in September 2014 based on CDS Catalog J/ApJ/758/15/ files table4.dat, table5.dat, table6.dat and table7.dat containing the X-ray properties of the 95 Chandra point sources found in this study. The information on the optical counterparts to (some of) the Chandra X-ray sources and on the X-ray point source classification (presented in Tables 16 and 17, respectively, of the reference paper) is not included herein. It was updated in September 2015 to include the unabsorbed 0.35-8.0 keV energy fluxes (in the parameter herein called b4_flux) from the second reference paper. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/ngc1893cxo
- Title:
- NGC 1893 Chandra X-Ray Point Source Catalog
- Short Name:
- NGC1893CXO
- Date:
- 13 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The outer Galaxy, where the environmental conditions are different from the solar neighbourhood, is a laboratory in which it is possible to investigate the dependence of the star formation process on the environmental parameters. The authors investigate the X-ray properties of NGC 1893, a young cluster (~ 1 - 2 Myr) in the outer part of the Galaxy (galactic radius >= 11 kpc), where they expect differences in the disk evolution and in the mass distribution of the stars, so as to explore the X-ray emission of its members and compare it with that of young stars in star forming regions near to the Sun. The authors analyze 5 deep Chandra ACIS-I observations with a total exposure time of 450 ks. Source events of the 1021 X-ray sources have been extracted with the IDL-based routine ACIS-Extract. Using spectral fitting and quantile analysis of X-ray spectra, they derive X-ray luminosities and compare the respective properties of Class II and Class III members. They also evaluate the variability of sources using the Kolmogorov-Smirnov test and identify flares in the lightcurves. The X-ray luminosity of NGC 1893 X-ray members is in the range 10<sup>29.5</sup> - 10<sup>31.5</sup> erg s<sup>-1</sup>. Diskless stars are brighter in X-rays than disk-bearing stars, given the same bolometric luminosity. The authors find that 34% of the 1021 lightcurves appear variable and that they show 0.16 flares per source, on the average. Comparing their results with those relative to the Orion Nebula Cluster, they find that, after accounting for observational biases, the X-ray properties of NGC 1893 and the Orion stars are very similar. The authors conclude that the X-ray properties of stars in NGC 1893 are not affected by the environment and that the stellar population in the outer Galaxy may have the same coronal properties as nearby star-forming regions. The X-ray luminosity properties and the X-ray luminosity function appear to be universal and can therefore be used for estimating distances and for determining stellar properties. 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/A74">CDS Catalog J/A+A/539/A74</a> file catalog.dat, the catalog of 1021 X-ray sources detected towards NGC 1893. 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:
- 13 Sep 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/ngc2516xmm
- Title:
- NGC 2516 Cluster XMM-Newton X-Ray Point Source Catalog
- Short Name:
- NGC2516XMM
- Date:
- 13 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the results from a deep X-ray survey of the young (~ 140 Myr), rich open cluster NGC 2516 obtained with the EPIC camera on board the XMM-Newton satellite. By combining the data from six observations, a high sensitivity, greater than a factor of 5 with respect to recent Chandra observations, has been achieved. Kaplan-Meier estimators of the cumulative X-ray luminosity distribution, statistically corrected for non-member contaminants, were built by the authors and compared to those of the nearly coeval Pleiades cluster. 431 X-ray sources were detected, and 234 of them have as optical counterparts cluster stars spanning the entire NGC 2516 main sequence. On the basis of X-ray emission and optical photometry, 20 new candidate members of the cluster have been identified; at the same time there are 49 X-ray sources without known optical or infrared counterpart. The X-ray luminosities of cluster stars span the range log L<sub>x</sub> (erg s<sup>-1</sup>) = 28.4 - 30.8. The representative coronal temperatures span the 0.3 - 0.6 keV (3.5 - 8 MK) range for the cool component and 1.0 - 2.0 keV (12 - 23 MK) for the hot one; similar values were found in other young open clusters like the Pleiades, IC 2391, and Blanco 1. While no significant differences were found in their X-ray spectra, NGC 2516 solar-type stars are definitely less luminous in X-rays than their nearly coeval Pleiades counterparts. The comparison with a previous ROSAT survey reveals the lack of variability amplitudes larger than a factor of 2 in solar-type cluster stars in a ~ 11 yr time scale, and thus activity cycles like in the Sun are probably absent or have a different period and amplitude in young stars. NGC 2516 has been observed several times with XMM-Newton during the first two years of satellite operations for calibration purposes. The observations used in this analysis span a period of 19 months with exposure times between 10 and 20 ks. All of these observations have been performed with the thick filter. In the combined EPIC datasets the authors detected 431 X-ray sources with a significance level greater than 5.0 sigma, which should lead statistically to at most one spurious source in the field of view. This table was created by the HEASARC in May 2007 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/450/993">CDS catalog J/A+A/450/993</a> files tablea1.dat and tableb1.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/ngc1512xmm
- Title:
- NGC 1512/NGC 1510 XMM-Newton X-Ray Point Source Catalog
- Short Name:
- NGC1512XMM
- Date:
- 13 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The galaxy NGC 1512 is interacting with the smaller galaxy NGC 1510 and shows a peculiar morphology, characterized by two extended arms immersed in an HI disc whose size is about four times larger than the optical diameter of NGC 1512. The authors have performed the first deep X-ray observation of the galaxies NGC 1512 and NGC 1510 with XMM-Newton to gain information on the population of X-ray sources and diffuse emission in this system of interacting galaxies. They have identified and classified the sources detected in the XMM-Newton field of view by means of spectral analysis, hardness-ratios calculated with a Bayesian method, X-ray variability, and cross-correlations with catalogs in optical, infrared, and radio wavelengths. They also made use of archival Swift (X-ray) and Australia Telescope Compact Array (radio) data to better constrain the nature of the sources detected with XMM-Newton. They detected 106 sources in the energy range of 0.2 - 12 keV, out of which 15 are located within the D<sub>25</sub> regions of NGC 1512 and NGC 1510 and at least six sources coincide with the extended arms. They identified and classified six background objects and six foreground stars. In the reference paper, they discuss the nature of a source within the D<sub>25</sub> ellipse of NGC 1512, whose properties indicate a quasi-stellar object or an intermediate ultra-luminous X-ray source. Taking into account the contribution of low-mass X-ray binaries and active galactic nuclei, the number of high-mass X-ray binaries detected within the D<sub>25</sub> region of NGC 1512 is consistent with the star formation rate obtained in previous works based on radio, infrared optical, and UV wavelengths. The authors detected diffuse X-ray emission from the interior region of NGC 1512 with a plasma temperature of kT = 0.68(0.31-0.87) keV and a 0.3 - 10 keV X-ray luminosity of 1.3E+38erg/s, after correcting for unresolved discrete sources. The galaxy pair NGC 1512/1510 was observed with XMM-Newton (ObsID: 0693160101) between 2012 June 16 (20:31 UTC) and 2012 June 17 (16:24 UTC) in a single, 63-ks exposure observation. The data analysis was performed through the XMM-Newton Science Analysis System (SAS) software (version 12.0.1). The observation was largely contaminated by high background due to proton flares. After rejecting time intervals affected by high background, the net good exposure time was reduced to 26.0 ks for PN, 39.8 ks for the MOS1 and 34.8 ks for the MOS2. For each instrument, the data were divided into five energy bands: <pre> B<sub>1</sub> : 0.2 - 0.5 keV B<sub>2</sub> : 0.5 - 1.0 keV B<sub>3</sub> : 1.0 - 2.0 keV B<sub>4</sub> : 2.0 - 4.5 keV B<sub>5</sub> : 4.5 - 12.0 keV </pre> For the PN, data were filtered to include only single events (PATTERN = 0) in the energy band B__1, and single and double events (PATTERN <= 4) for the other energy bands. The authors excluded the energy range 7.2 - 9.2 keV to reduce the background produced by strong fluorescence lines in the outer detector area. For the MOS, single to quadruple events (PATTERN <= 12) were selected. The source detection procedure is described in Section 2.1 of the reference paper. In the final step, the authors adopted a minimum likelihood of L = 6. They removed false detections (artifacts on the detectors or diffuse emission structures) by visual inspection. They detected 106 total point sources in the NGC 1512/1510 field of view. This table was created by the HEASARC in July 2014 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/566/A115">CDS Catalog J/A+A/566/A115</a> files tableb1.dat and tableb2.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:
- 13 Sep 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:
- 13 Sep 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/ngc2264xmm
- Title:
- NGC 2264 XMM-Newton X-Ray Point Source Catalog
- Short Name:
- NGC2264XMM
- Date:
- 13 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains (some of) the results from an X-ray imaging survey of the young cluster NGC 2264, carried out with the European Photon Imaging Cameras (EPIC) on board the XMM-Newton spacecraft. XMM-Newton EPIC observations were made separately of the northern and southern portions of NGC 2264 on 2001 March 20 and 2002 March 17 - 18, respectively. Details concerning the two pointings are summarized in Table 1 of the reference paper. The nominal integration time was 42 ks for both observations. The three EPIC cameras were operated in full window mode. To prevent contamination of the X-ray images by the XUV and EUV emission of the optically and UV-bright sources in the field of view, the thick filter was used, which imposes a strong cut-off in the response at the lower energies. The X-ray data are merged with extant optical and near-infrared photometry, spectral classifications, H-alpha emission strengths, and rotation periods to examine the interrelationships between coronal and chromospheric activity, rotation, stellar mass, and internal structure for a statistically significant sample of pre-main-sequence stars. Out of the 316 distinct point-like sources that were detected at >= 3-sigma levels in one or more of six EPIC images, a total of 300 distinct X-ray sources can be identified with optical or near-infrared counterparts. The sources are concentrated within three regions of the cluster: in the vicinity of S Mon, within the large emission/reflection nebulosity southwest of S Mon, and along the broad ridge of molecular gas that extends from the Cone Nebula to the NGC 2264 IRS 2 field. From the extinction-corrected color-magnitude diagram of the cluster, ages and masses for the optically identified X-ray sources are derived. A median age of ~ 2.5 Myr and an apparent age dispersion of ~ 5 Myr are suggested by pre-main-sequence evolutionary models. The X-ray luminosity of the detected sources appears well-correlated with bolometric luminosity, although there is considerable scatter in the relationship. Stellar mass contributes significantly to this dispersion, while isochronal age and rotation do not. X-ray luminosity and mass are well correlated such that L<sub>X</sub> ~ (M/M<sub>solar</sub>)<sup>1.5</sup>, which is similar to the relationship found within the younger Orion Nebula Cluster. No strong evidence is found for a correlation between E(H-K), the near-infrared color excess, and the fractional X-ray luminosity, which suggests that optically thick dust disks have little direct influence on the observed X-ray activity levels. Among the X-ray-detected weak-line T Tauri stars, the fractional X-ray luminosity, L<sub>X</sub>/L<sub>bol</sub>, is moderately well correlated with the fractional H-alpha luminosity, L<sub>H(alpha)</sub>/L<sub>bol</sub>, but only at the 2-sigma level of significance. The cumulative distribution functions for the X-ray luminosities of the X-ray-detected classical and weak-line T Tauri stars within the cluster are comparable, assuming the demarcation between the two classes is at an H-alpha equivalent width of 10 Angstroms. However, if the non-detections in X-rays for the entire sample of H-alpha emitters known within the cluster are taken into account, then the cumulative distribution functions of these two groups are clearly different, such that classical T Tauri stars are underdetected by at least a factor of 2 relative to the weak-line T Tauri stars. Examining a small subsample of X-ray-detected stars that are probable accretors based on the presence of strong H-alpha emission and near-infrared excess, the authors conclude that definitive non-accretors are ~ 1.6 times more X-ray luminous than their accreting counterparts. In agreement with earlier published findings for the Orion Nebula Cluster, the authors find a slight positive correlation (valid at the 2-sigma confidence level) between L<sub>X</sub>/L<sub>bol</sub> and the rotation period in NGC 2264 stars. The lack of a strong anti-correlation between X-ray activity and rotation period in the stellar population of NGC 2264 suggests that either the deeply convective T Tauri stars are rotationally saturated or that the physical mechanism responsible for generating magnetic fields in pre-main-sequence stars is distinct from the one that operates in evolved main-sequence stars. This table was created by the HEASARC in September 2007 based on the electronic version of Table 2 from the reference paper which was obtained from the electronic AJ site. This is a service provided by NASA HEASARC .