J/ApJS/177/465ivo://CDS.VizieR/J/ApJS/177/465doi:10.26093/cds/vizier.21770465CDSFridriksson J.K.Homan J.Lewin W.H.G.Kong A.K.H.Pooley D.2018-02-01T11:50:43Z2009-10-28T14:37:16ZCDS support team

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

cds-question@unistra.frx-ray-sourcesx-ray-binary-starsgalaxiesWe analyze data from five Chandra observations of the spiral galaxy NGC 6946 and from three Chandra observations of the irregular/spiral interacting galaxy pair NGC 4485/4490, with an emphasis on investigating the long-term variability exhibited by the source populations. We detect 90 point sources coincident with NGC 6946 down to luminosities of a few times 10^36^ergs/s, and 38 sources coincident with NGC 4485/90 down to a luminosity of ~1x10^37^ergs/s. Twenty-five (15) sources in NGC 6946 (NGC 4485/90) exhibit long-term (i.e., weeks to years) variability in luminosity; 11 (4) are transient candidates. The single ultraluminous X-ray source (ULX) in NGC 6946 and all but one of the eight ULXs in NGC 4485/90 exhibit long-term flux variability. Two of the ULXs in NGC 4485/90 have not been identified before as ultraluminous sources. The widespread variability in both systems is indicative of the populations being dominated by X-ray binaries, and this is supported by the X-ray colors of the sources. The distribution of colors among the sources indicates a large fraction of high-mass X-ray binaries in both systems. The shapes of the X-ray luminosity functions of the galaxies do not change significantly between observations and can be described by power laws with cumulative slopes ~0.6-0.7 (NGC 6946) and ~0.4 (NGC 4485/90).2008ApJS..177..465Fhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/177/465CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/chandra : The Chandra Archive Log (CXC, 1999-)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/177/465https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/177/465http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/177/465https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJS/177/465https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJS/177/465http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJS/177/465GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJS/177/465/ngc6946 (Basic and spectral properties for NGC 6946)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/177/465/ngc6946?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/177/465/ngc6946?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/177/465/ngc6946?GETtext/xml+votable180.050000true308.5794260.168840.005555555555555556Cone search capability for table J/ApJS/177/465/ngc4485 (Basic and spectral properties for NGC 4485)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/177/465/ngc4485?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/177/465/ngc4485?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/177/465/ngc4485?GETtext/xml+votable180.050000true187.6050641.656910.0055555555555555566/10905 15592 15593https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJS/177/465?format=asciiX-raydefaultJ/ApJS/177/465/ngc6946Basic and spectral properties for NGC 6946CommComments (5)meta.notechare_HR2? Error on HR2stat.errorfloatnullableHR1co? HR1 for combined observations (3)meta.notefloatnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint[FHL2008]Number identificationmeta.idintCXOUSource designation (HHMMSS.s+DDMMSS)meta.id;meta.maincharRAJ2000Right ascension in decimal degrees (J2000)degpos.eq.ra;meta.mainDEJ2000Declination in decimal degrees (J2000)degpos.eq.dec;meta.mainSNSignal-to-noise ratio (1)stat.snrfloatObsIDObservation ID numbermeta.idintl_FluxLimit flag on Flux (2)meta.code.error;phot.fluxcharFlux? Photon flux in the 0.3-7keV band (2)ph.ks**-1.m**-2phot.flux;em.X-ray.mediumfloatnullableE_Flux? Positive error of Flux (2)ph.ks**-1.m**-2stat.error;stat.maxfloatnullablee_Flux? Negative error of Flux (2)ph.ks**-1.m**-2stat.error;phot.fluxfloatnullableFcoPhoton flux in the co-added exposure (2)ph.ks**-1.m**-2phot.flux;em.X-rayfloate_FcoError on Fco (2)ph.ks**-1.m**-2stat.errorfloatXLumAverage X-ray luminosity in the 0.3-7keV band (3)1e+30Wphys.luminosity;em.X-rayfloatXLumaxMaximum of X-ray luminosity in the 0.3-7keV band (4)1e+30Wphys.luminosity;em.X-rayfloatHR1? HR1 (1)meta.notefloatnullablee_HR1? Error on HR1stat.errorfloatnullableHR2? HR2 (2)meta.notefloatnullablee_HR1co? Error on HR1costat.errorfloatnullableHR2co? HR2 for combined observationsmeta.notefloatnullablee_HR2co? Error on HR2costat.errorfloatnullableJ/ApJS/177/465/ngc4485Basic and spectral properties for NGC 4485CommComments (5)meta.notecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint[FHL2008]Number identificationmeta.idintCXOUSource designation (HHMMSS.s+DDMMSS)meta.id;meta.maincharRAJ2000Right ascension in decimal degrees (J2000)degpos.eq.ra;meta.mainDEJ2000Declination in decimal degrees (J2000)degpos.eq.dec;meta.mainSNSignal-to-noise ratio (1)stat.snrfloatObsIDObservation ID numbermeta.idintl_FluxLimit flag on Flux (2)meta.code.error;phot.fluxcharFlux? Photon flux in the 0.3-7keV band (2)ph.ks**-1.m**-2phot.flux;em.X-ray.mediumfloatnullableE_Flux? Positive error of Flux (2)ph.ks**-1.m**-2stat.error;stat.maxfloatnullablee_Flux? Negative error of Flux (2)ph.ks**-1.m**-2stat.error;phot.fluxfloatnullableFcoPhoton flux in the co-added exposure (2)ph.ks**-1.m**-2phot.flux;em.X-rayfloate_FcoError on Fco (2)ph.ks**-1.m**-2stat.errorfloatXLumAverage X-ray luminosity in the 0.3-7keV band (3)1e+30Wphys.luminosity;em.X-rayfloatXLumaxMaximum of X-ray luminosity in the 0.3-7keV band (4)1e+30Wphys.luminosity;em.X-rayfloatHR1? HR1 (1)meta.notefloatnullablee_HR1? Error on HR1stat.errorfloatnullableHR2? HR2 (2)meta.notefloatnullablee_HR2? Error on HR2stat.errorfloatnullableHR1co? HR1 for combined observations (3)meta.notefloatnullablee_HR1co? Error on HR1costat.errorfloatnullableHR2co? HR2 for combined observationsmeta.notefloatnullablee_HR2co? Error on HR2costat.errorfloatnullableJ/ApJS/177/465/table9Chandra variability properties for NGC 6946 sourcesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint[FHL2008]Number identificationmeta.id;meta.mainintCXOUSource designation (HHMMSS.s+DDMMSS)meta.idcharK-S1043? K-S test for short-term flux variability for obs. ID 1043 (G1)stat.probability;src.vardoublenullableK-S4404? K-S test for short-term flux variability for obs. ID 4404 (G1)stat.probability;src.vardoublenullableK-S4631? K-S test for short-term flux variability for obs. ID 4631 (G1)stat.probability;src.vardoublenullableK-S4632? K-S test for short-term flux variability for obs. ID 4632 (G1)stat.probability;src.vardoublenullableK-S4633? K-S test for short-term flux variability for obs. ID 4633 (G1)stat.probability;src.varfloatnullableSvarSignificance parameter for long-term flux variability (G2)stat.probability;src.varfloatl_RLimit flag on Rmeta.code.errorcharRLong-term flux variability (G3)phot.flux;arith.ratiofloatSHR1Significance parameter for the variability in the Hardness Ratio 1 (G4)stat.probability;src.varfloatSHR2Significance parameter for the variability in the Hardness Ratio 2 (G5)stat.probability;src.varfloatCommComments (G6)meta.notecharJ/ApJS/177/465/table10Chandra variability properties for NGC 4485/4490 sourcesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint[FHL2008]Number identificationmeta.id;meta.mainintCXOUSource designation (HHMMSS.s+DDMMSS)meta.idcharK-S1579? K-S test for short-term flux variability for obs. ID 1579 (G1)stat.probability;src.vardoublenullableK-S4725? K-S test for short-term flux variability for obs. ID 4725 (G1)stat.probability;src.vardoublenullableK-S4726K-S test for short-term flux variability for obs. ID 4726 (G1)stat.probability;src.vardoubleSvarSignificance parameter for long-term flux variability (G2)stat.probability;src.varfloatl_RLimit flag on Rmeta.code.errorcharRLong-term flux variability (G3)phot.flux;arith.ratiofloatSHR1Significance parameter for the variability in the Hardness Ratio 1 (G4)stat.probability;src.varfloatSHR2Significance parameter for the variability in the Hardness Ratio (G5)stat.probability;src.varfloatCommComments (G6)meta.notechar