J/other/NatAs/7.ivo://CDS.VizieR/J/other/NatAs/7.967doi:10.26093/cds/vizier/dt/hkjghCDSMeyer E.T.Shaik A.Tang Y.Reid N.Reddy K.Breiding P.,Georganopoulos M.Chiaberge M.Perlman E.Clautice D.Sparks W.,Denigris N.Trevor M.2026-03-04T20:03:36Z2024-07-25T13:44:28ZCDS support team

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

cds-question@unistra.frradio-sourcesx-ray-sourcesredshiftedUnexpectedly strong X-ray emission from extragalactic radio jets on kiloparsec scales has been one of the major discoveries of Chandra, the only X-ray observatory capable of sub-arcsecond-scale imaging. The origin of this X-ray emission, which appears as a second spectral component from that of the radio emission, has been debated for over two decades. The most commonly assumed mechanism is inverse-Compton upscattering of the cosmic microwave background by very low-energy electrons in a still highly relativistic jet. Under this mechanism, no variability in the X-ray emission is expected. Here we report the detection of X-ray variability in the large-scale jet population, using a novel statistical analysis of 53 jets with multiple Chandra observations. Taken as a population, we find that the distribution of P values from a Poisson model is strongly inconsistent with steady emission, with a global P value of 1.96x10^-4^ under a Kolmogorov-Smirnov test against the expected uniform (0, 1) distribution. These results strongly imply that the dominant mechanism of X-ray production in kiloparsec-scale jets is synchrotron emission by a second population of electrons reaching multi-teraelectronvolt energies. X-ray variability on the timescale of months to a few years implies extremely small emitting volumes much smaller than the cross-section of the jet.2023NatAs...7..967Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/other/NatAs/7.967CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/chandra : The Chandra Archive Log (CXC, 1999-)http://www.vla.nrao.edu/astro/nvas : NRAO VLA Archive Survey Images Pagehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/other/NatAs/7.967https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/other/NatAs/7.967http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/other/NatAs/7.967https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/other/NatAs/7.967https://vizier.iucaa.in/viz-bin/votable?-source=J/other/NatAs/7.967http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/other/NatAs/7.967GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/other/NatAs/7.967/tables2 (Characteristics of our 55 jets)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/other/NatAs/7.967/tables2?https://vizier.iucaa.in/viz-bin/conesearch/J/other/NatAs/7.967/tables2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/other/NatAs/7.967/tables2?GETtext/xml+votable180.050000true4.1291779.280530.0055555555555555566/911 1263 2214 4014 4376 5018 5597 5794 7061 7426 8858 9633 10217 10355 10529 10601 11512 11652 11715 14744 16027 16059 16093 16184 18035 18065 18669 18683 19842 20099 21358 22364 24775 25255 25302 25472 25863 26245 26292 27382 27580 27714 28315 28540 31080 31344 34104 35079 37385 38682 43281 44908 45446 46040 48595https://cdsarc.cds.unistra.fr/viz-bin/moc/J/other/NatAs/7.967?format=asciiX-rayRadiodefaultJ/other/NatAs/7.967/tables1Radio observationsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJNameSourcemeta.id;meta.maincharDateObsservation datetime.epochnullableTelTelescopemeta.id;instr.telcharProjetProject Codemeta.codecharFreqObserved frequencyGHzem.freqfloatImage[abcd] Image (1)obs.imagecharMajorBeam major axisarcsecphys.angSize;instr.beamfloatMinorBeam minor axisarcsecphys.angSize;instr.beamfloatJ/other/NatAs/7.967/tables2Characteristics of our 55 jetsSimbadNameSimbad column added by the CDSmeta.idcharnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJNameIAU Name (J2000), JHHMM+DDMMmeta.id;meta.maincharNameCommon namemeta.idcharClassJet classificationsrc.classcharRAJ2000Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainzRedshiftsrc.redshiftdoubleJetAngleEstimated jet angledegpos.posAngfloatNRegNumber of distinct jet features analysedmeta.numberintNObsNumber of distinct Chandra observations (epochs)meta.numberintBaselineMaximum and minimum time separation between observationstime.intervalcharScaleCosmology-corrected angular size scalekpc/arcsecphys.angSizefloatNHGalactic Hydrogen column density value used1e+22cm**-2phys.columnDensity;pos.galacticdoubleJetLengthTotal observed jet length in arcsecondsarcsecsrc.morph.scLengthfloatJetLength2Total observed jet length in kiloparsecskpcsrc.morph.scLengthfloatJ/other/NatAs/7.967/tables3Characteristics of each Chandra observationrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJNameIAU name of the target sourcemeta.id;meta.maincharEpochIDChandra observation ID numbermeta.id;obsintDateDecimal Date of the observationyrtime.epoch;obsdoubleRStreakFlag column for readout streak correctionmeta.codecharExpTotInitial total exposure timekstime.duration;obs.exposurefloatExpFiltTotal observing time after removing background flaresksinstr.backgroundfloatJ/other/NatAs/7.967/tables4Characteristics of all 155 analysis regions, as well as the 'total jet' regions for jets with more than one knotMLErate? Estimated mean source ratecount.s**-1.cm**-2phot.count;em.X-raydoublenullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJNameIAU name of the sourcemeta.id;meta.maincharKnotIDregion namemeta.id;obs.fieldcharCTtotTotal counts in the region over all observationsctphot.countintSTmin? Upper sensitivity thresholdinstr.sensitivitydoublenullableSTmax? Lower sensitivity thresholdinstr.sensitivitydoublenullableBGTypetype of background region used, annulus (ANN) or generic (GEN)meta.codecharBGModelBackground model or treatment used for the spectral fitinstr.backgroundcharKnotAreaKnot area in ACIS pixelspixphys.areafloatKnotArea2Knot area in arcseconds squaredarcsec**2phys.areadoubleF1keV? Flux normalisation of the region SHERPA fitnJyphot.flux;em.X-raydoublenullablee_F1keV? Flux normalisation of the region SHERPA fit errornJystat.errordoublenullableGamma? Spectral index from the region SHERPA fitspect.indexfloatnullablee_Gamma? Spectral index from the region SHERPA fit errorstat.errorfloatnullablepvalue? Single-region p-value from the Poisson modelstat.fit.goodnessdoublenullableJ/other/NatAs/7.967/tables5Details specific to a particular knot and epoch of observationrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJNameIAU name of the sourcemeta.id;meta.maincharKnotRegion nameobs.fieldcharEpochIDChandra observation ID numbermeta.id;obscharExpSourceSource region exposurekstime.expodoubleExpBkgExposure background exposureksinstr.background;obs.exposuredoubleSourceCounts source region countsctphot.countintBackgroundCounts background region countsctphot.count;obs.fieldintECFEncircled counts fractionphot.countfloatFluxEstimated source fluxcount.s**-1.cm**-2phot.flux.density;em.radiodouble