OMEGCENCX2 ivo://nasa.heasarc/omegcencx2 NASA/GSFC HEASARC Henleywillis et al. 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source The authors identify 233 X-ray sources, of which 95 are new, in a 222-ks exposure of omega Centauri with the Chandra X-ray Observatory's Advanced CCD Imaging Spectrometer detector. The limiting unabsorbed flux in the core is f<sub>X</sub>(0.5-6.0keV) ~= 3 x 10<sup>-16</sup> erg/s/cm<sup>2</sup> (L<sub>x</sub> ~= 1 x 10<sup>30</sup> erg/s at 5.2kpc). The authors estimate that ~60 +/- 20 of these are cluster members, of which ~30 lie within the core (r<sub>c</sub> = 155 arcsec), and another ~30 between 1-2 core radii. They identify four new optical counterparts, for a total of 45 likely identifications. Probable cluster members include 18 cataclysmic variables (CVs) and CV candidates, one quiescent low-mass X-ray binary, four variable stars, and five stars that are either associated with omega Cen's anomalous red giant branch or are sub-subgiants. The authors estimate that the cluster contains 40 +/- 10 CVs with L_x_> 10<sup>31</sup> erg/s, confirming that CVs are underabundant in omega Cen relative to the field. Intrinsic absorption is required to fit X-ray spectra of six of the nine brightest CVs, suggesting magnetic CVs, or high-inclination systems. Though no radio millisecond pulsars (MSPs) are currently known in omega Cen, more than 30 unidentified sources have luminosities and X-ray colors like those of MSPs found in other globular clusters; these could be responsible for the Fermi-detected gamma-ray emission from the cluster. The authors identify a CH star as the counterpart to the second brightest X-ray source in the cluster and argue that it is a symbiotic star. This is the first such giant/white dwarf binary to be identified in a globular cluster. The data were obtained over two long exposures of omega Cen using the imaging array of the Chandra X-ray Observatory's ACIS-I on 2012 April 16 and 17. The data sets have a combined exposure time of ~222ks (173.7 and 48.5ks for ObsIDs 13726 and 13727, respectively). This table was created by the HEASARC in June 2018 based upon the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/MNRAS/479/2834">CDS Catalog J/MNRAS/479/2834</a> file table1.dat. This is a service provided by NASA HEASARC . 2018MNRAS.479.2834H https://heasarc.gsfc.nasa.gov/W3Browse/all/omegcencx2.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=omegcencx2& GET text/xml 180 99999 true 201.65279167 -47.62484722 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=omegcencx2 GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_omegcencx2&Action=More+Options&Action=Parameter+Search&ConeAdd=1 CHANDRA 0.0166666666666667 X-ray public omegcencx2 Omega Centauri Globular Cluster Chandra Deep Survey X-Ray Point name Catalog Source Designation meta.id;meta.main char nullable ra Right Ascension degree pos.eq.ra;meta.main double nullable dec Declination degree pos.eq.dec;meta.main double nullable mb_flux Medium (0.5-4.5keV) Band X-Ray Flux erg/s/cm^2 phot.flux;em.X-ray double nullable tb_flux Total (0.5-6.0keV) Band X-Ray Flux erg/s/cm^2 phot.flux;em.X-ray double nullable sb_flux Soft (0.5-2.0keV) Band X-Ray Flux erg/s/cm^2 phot.flux;em.X-ray double nullable fluxvar 0.5-6.0keV Band Flux Ratio phot.flux;arith.ratio double nullable optical_id Optical Identification meta.note char nullable bii Galactic Latitude degree pos.galactic.lat double nullable error_radius 95% Confidence Error Radius arcsec stat.error;pos double nullable radial_distance Offset pos.angDistance double nullable hardness_ratio Logarithm of the Soft-to-Hard X-Ray Count Ratio phot.flux;arith.ratio;em.X-ray double nullable hb_total_counts Detected Hard (1.5-6.0keV) Band X-Ray Counts ct phot.count;em.X-ray short nullable sb_total_counts Detected Soft (0.5-1.5keV) Band X-Ray Counts ct phot.count;em.X-ray short nullable fluxvar_flag Flag [g] Indicates Note Concerning Flux Ratio meta.note char nullable mb_total_counts Detected Medium (0.5-4.5keV) Band X-Ray Counts ct phot.count;em.X-ray short nullable source_flag Flag [Y] Indicates Name Assigned in This Work meta.code;src char nullable hb_counts Corrected Hard (1.5-6.0keV) Band X-Ray Counts ct phot;em.X-ray double nullable mb_counts Corrected Medium (0.5-4.5keV) Band X-Ray Counts ct phot.count;em.X-ray double nullable sb_counts Corrected Soft (0.5-1.5keV) Band X-Ray Counts ct phot;em.X-ray double nullable lii Galactic Longitude degree pos.galactic.lon double nullable source_id Unique Source Identifier meta.id;src char nullable "__x_ra_dec" System unit vector column double nullable "__y_ra_dec" System unit vector column double nullable "__z_ra_dec" System unit vector column double nullable "__row" System index column char nullable