J/ApJS/269/10ivo://CDS.VizieR/J/ApJS/269/10doi:10.26093/cds/vizier.22690010CDSKashyap V.L.Guarcello M.G.Wright N.J.Drake J.J.Flaccomio E.,Aldcroft T.L.Albacete Colombo J.F.Briggs K.Damiani F.Drew J.E.,Martin E.L.Micela G.Naylor T.Sciortino S.2024-11-06T20:30:15Z2024-02-28T09:34:40ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frx-ray-sourcesWe have devised a predominantly Naive Bayes-based method to classify X-ray sources detected by Chandra in the Cygnus OB2 association into members, foreground objects, and background objects. We employ a variety of X-ray, optical, and infrared characteristics to construct likelihoods using training sets defined by well-measured sources. Combinations of optical photometry from the Sloan Digital Sky Survey (riz) and Isaac Newton Telescope Photometric H{alpha} Survey (rIiIH{alpha}), infrared magnitudes from United Kingdom Infrared Telescope Deep Sky Survey and Two-Micron All Sky Survey (JHK), X-ray quantiles and hardness ratios, and estimates of extinction Av are used to compute the relative probabilities that a given source belongs to one of the classes. Principal component analysis is used to isolate the best axes for separating the classes for the photometric data, and Gaussian component separation is used for X-ray hardness and extinction. Errors in the measurements are accounted for by modeling as Gaussians and integrating over likelihoods approximated as quartic polynomials. We evaluate the accuracy of the classification by inspection and reclassify a number of sources based on infrared magnitudes, the presence of disks, and spectral hardness induced by flaring. We also consider systematic errors due to extinction. Of the 7924 X-ray detections, 5501 have a total of 5597 optical/infrared matches, including 78 with multiple counterparts. We find that ~6100 objects are likely association members, ~1400 are background objects, and ~500 are foreground objects, with an accuracy of 96%, 93%, and 80%, respectively, with an overall classification accuracy of approximately 95%.2023ApJS..269...10Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/269/10CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)I/345 : Gaia DR2 (Gaia Collaboration, 2018)J/AJ/101/1408 : Massive stars in Cyg OB2. (Massey+ 1991)J/A+A/474/495 : X flares from CygOB2 young stars (Albacete Colombo+, 2007)J/ApJ/663/320 : IR-through-UV extinction curve (Fitzpatrick+, 2007)J/ApJ/659/585 : X-ray classif. of young star clusters (Hojnacki+, 2007)J/ApJS/184/84 : X-ray sources in Cyg OB2 region (Wright+, 2009)J/ApJ/720/679 : Optical spectroscopy in Cygnus X region (Beerer+, 2010)J/A+A/521/A18 : Blue stars with disk phot. in NGC 6611 (Guarcello+, 2010)J/ApJ/713/871 : Sources in Cyg-OB2 from X-ray (Wright+, 2010)J/ApJS/194/4 : Classification of CCCP X-ray sources (Broos+, 2011)J/ApJS/202/19 : riz photometry in Cyg OB2 (Guarcello+, 2012)J/ApJ/773/135 : Disk-bearing stars in Cygnus OB2 (Guarcello+, 2013)J/ApJS/209/28 : MYStIX Wide-Field NIR data: crowded fields (King+, 2013)J/ApJS/209/27 : MYStIX: the Chandra X-ray sources (Kuhn+, 2013)J/MNRAS/449/741 : The massive star population of Cygnus OB2 (Wright+, 2015)J/MNRAS/485/1085 : Classification of emission-line galaxies (Stampoulis+, 2019)J/ApJS/269/7 : Chandra Cyg OB2 Legacy Survey: X-ray Catalog (Wright+ 2023)J/ApJS/269/9 : Opt-IR xids of Chandra sources in CygOB2 (Guarcello+, 2023)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/269/10https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/269/10http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/269/10https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJS/269/10https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJS/269/10http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJS/269/10GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJS/269/10/table3 (Catalog of classifications)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/269/10/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/269/10/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/269/10/table3?GETtext/xml+votable180.050000true307.5313441.467568060.0055555555555555566/14670-14671 14692-14694https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJS/269/10?format=asciiX-raydefaultJ/ApJS/269/10/table3Catalog of classificationsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint[WDG2023][1/7924] Source number as in Wright+ 2023, J/ApJS/269/7 (1)meta.id;meta.mainintMatchOptical/IR match? ("Multiple": 174 occurrences, "Yes": 5423 occurrences, or "No")meta.codecharpFore[0/1] Probability value of being a foreground memberstat.probabilityfloatpMemb[0/1] Probability value of being a memberstat.probabilityfloatpBack[0/1] Probability value of being a background memberstat.probabilityfloatClassClassification ("background": 1360 occurrences, "foreground": 491 occurrences or "member":6169 occurrences)meta.code.membercharn_ClassAdditional note(s) on Class (2)meta.notechar_RAPositions from the Chandra Cygnus OB2 Legacy Survey (Wright+ 2023, J/ApJS/269/7) (right ascension part)degpos.eq.ra;meta.main_DEPositions from the Chandra Cygnus OB2 Legacy Survey (Wright+ 2023, J/ApJS/269/7) (declination part)degpos.eq.dec;meta.main