J/ApJ/735/26ivo://CDS.VizieR/J/ApJ/735/26doi:10.26093/cds/vizier.17350026CDSSell P.H.Pooley D.Zezas A.Heinz S.Homan J.Lewin W.H.G.2017-06-22T14:29:11Z2013-01-15T16:37:32ZCDS support team

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

cds-question@unistra.frgalaxiesx-ray-sourcesspectroscopyastronomical-modelsWe present an analysis of 15 Chandra observations of the nearby spiral galaxy M81 taken over the course of six weeks in 2005 May-July. Each observation reaches a sensitivity of ~10^37^erg/s. With these observations and one previous deeper Chandra observation, we compile a master source list of 265 point sources, extract and fit their spectra, and differentiate basic populations of sources through their colors. We also carry out variability analyses of individual point sources and of X-ray luminosity functions (XLFs) in multiple regions of M81 on timescales of days, months, and years. We find that, despite measuring significant variability in a considerable fraction of sources, snapshot observations provide a consistent determination of the XLF of M81. We also fit the XLFs for multiple regions of M81 and, using common parameterizations, compare these luminosity functions to those of two other spiral galaxies, M31 and the Milky Way.2011ApJ...735...26Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/735/26CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/chandra : The Chandra Archive Log (CXC, 1999-2012)J/ApJS/192/10 : Chandra ACIS survey in 383 nearby galaxies. I. (Liu, 2011)J/AJ/141/129 : Chandra Transmission Grating Data Cat. (Huenemoerder+, 2011)J/ApJS/157/59 : Ultraluminous X-ray sources in nearby galaxies (Liu+, 2005)J/ApJS/144/213 : Chandra X-ray observations of M81 (Swartz+, 2003)J/A+A/368/797 : Soft X-ray properties of Seyfert galaxies (Pfefferkorn+, 2001)J/ApJ/554/202 : ROSAT X-ray observations of M81 (Immler+, 2001)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/735/26https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/735/26http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/735/26https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/735/26https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/735/26http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/735/26GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/735/26/xsources (Merged extraction and fit data of sources in the master and borderline source lists)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/735/26/xsources?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/735/26/xsources?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/735/26/xsources?GETtext/xml+votable180.050000true149.07603668.8229640.0055555555555555566/7603 7604 7606https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/735/26?format=asciiX-rayOpticaldefaultJ/ApJ/735/26/xsourcesMerged extraction and fit data of sources in the master and borderline source listsVarS1? Variability statistic (3)src.var.indexfloatnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeqSource index number (G1)meta.id;meta.maincharn_SeqSource off chip (2)meta.notecharRAJ2000Right Ascension in decimal degrees (J2000)degpos.eq.ra;meta.mainDEJ2000Declination in decimal degrees (J2000)degpos.eq.dec;meta.mainOAA? Average off-axis anglearcmininstr.offset;stat.meanfloatnullableSCts? Total source countsctphot.count;em.X-rayintnullableBCts? Total background countsctphot.count;em.X-rayfloatnullableSoft? Net soft (0.5-1keV) countsctphot.count;em.X-rayfloatnullablee_Soft? Lower limit uncertainty in Soft (1)ctstat.errorfloatnullableE_Soft? Upper limit uncertainty in Softctstat.error;stat.maxfloatnullableMed? Net medium (1-2keV) countsctphot.count;em.X-rayfloatnullablee_Med? Lower limit uncertainty in Med (1)ctstat.errorfloatnullableE_Med? Upper limit uncertainty in Medctstat.error;stat.maxfloatnullableHard? Net hard (2-8keV) countsctphot.count;em.X-rayfloatnullablee_Hard? Lower limit uncertainty in Hard (1)ctstat.errorfloatnullableE_Hard? Upper limit uncertainty in Hardctstat.error;stat.maxfloatnullablePSF? Average PSF fraction enclosed by extraction region%instr.det.psf;arith.ratiofloatnullableObs1Observations used to derive VarS1meta.id;obscharVarS2? Variability statistic (4)src.var.indexfloatnullableS03Cross-match with Swartz+ 2003, Cat. J/ApJS/144/213, within 10"meta.ref.urlintnullableModelModel type: plaw=power law, or bbod=blackbodymeta.note;phys.luminosity;meta.modelledcharn_Model[ab] Note on Model type (5)meta.notecharParam? Photon Index (plaw) or kT (bbod) of Modelspect.indexfloatnullablee_Param? Lower limit uncertainty in Param (6)stat.errorfloatnullableE_Param? Upper limit uncertainty in Param (6)stat.error;stat.maxfloatnullableNorm? Model normalization (7)stat.fit.paramdoublenullablee_Norm? Lower limit uncertainty in Norm (6)stat.errordoublenullableE_Norm? Upper limit uncertainty in Norm (6)stat.error;stat.maxdoublenullableNH? The H I column density (8)1e+22cm**-2phys.columnDensityfloatnullablee_NH? Lower limit uncertainty in NH (6)1e+22cm**-2stat.errorfloatnullableE_NH? Upper limit uncertainty in NH (6)1e+22cm**-2stat.error;stat.maxfloatnullableCStat? Total best-fit C-Statistic (for the source and background models together)stat.fit.paramfloatnullableDOF[1012/1016]? Degrees of Freedom (9)stat.fit.dofintnullableLum? The 0.5-8 keV luminosity (10)1e+30Wphys.luminosity;em.X-rayfloatnullablee_Lum? Lower limit uncertainty in Lum (6)1e+30Wstat.errorfloatnullableE_Lum? Upper limit uncertainty in Lum (6)1e+30Wstat.error;stat.maxfloatnullableComComments about source extraction (11)meta.note;phys.angSizecharSimbadSimbad column added by the CDSmeta.refchar