J/AJ/147/143ivo://CDS.VizieR/J/AJ/147/143doi:10.26093/cds/vizier.51470143CDSHovatta T.Aller M.F.Aller H.D.Clausen-Brown E.Homan D.C.,Kovalev YU.Y.Lister M.L.Pushkarev A.B.Savolainen T.2018-01-08T06:37:50Z2014-10-21T12:14:33ZCDS support team

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

cds-question@unistra.frquasarsactive-galactic-nucleibl-lacertae-objectsradio-galaxiesredshiftedWe have obtained milliarcsecond-scale spectral index distributions for a sample of 190 extragalactic radio jets through the Monitoring of Jets in Active Galactic Nuclei with the VLBA Experiments (MOJAVE) project. The sources were observed in 2006 at 8.1, 8.4, 12.1, and 15.4GHz, and we have determined spectral index maps between 8.1 and 15.4GHz to study the four-frequency spectrum in individual jet features. We have performed detailed simulations to study the effects of image alignment and (u, v)-plane coverage on the spectral index maps to verify our results. We use the spectral index maps to study the spectral index evolution along the jet and determine the spectral distributions in different locations of the jets. The core spectral indices are on average flat with a mean value of +0.22+/-0.03 for the sample, while the jet spectrum is in general steep with a mean index of -1.04+/-0.03. A simple power-law fit is often inadequate for the core regions, as expected if the cores are partially self-absorbed. The overall jet spectrum steepens at a rate of about -0.001 to -0.004 per deprojected parsec when moving further out from the core with flat spectrum radio quasars having significantly steeper spectra (mean -1.09+/-0.04) than the BL Lac objects (mean -0.80+/-0.05). However, the spectrum in both types of objects flattens on average by ~0.2 at the locations of the jet components indicating particle acceleration or density enhancements along the jet. The mean spectral index at the component locations of -0.81+/-0.02 corresponds to a power-law index of ~2.6 for the electron energy distribution. We find a significant trend that jet components with linear polarization parallel to the jet (magnetic field perpendicular to the jet) have flatter spectra, as expected for transverse shocks. Compared to quasars, BL Lacs have more jet components with perpendicular magnetic field alignment, which may explain their generally flatter spectra. The overall steepening of the spectra with distance can be explained with radiative losses if the jets are collimating or with the evolution of the high-energy cutoff in the electron spectrum if the jets are conical. This interpretation is supported by a significant correlation with the age of the component and the spectral index, with older components having steeper spectra.2014AJ....147..143Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/147/143CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVII/258 : Quasars and Active Galactic Nuclei (13th Ed.) (Veron+ 2010)J/AJ/144/105 : MOJAVE. VIII. Faraday rotation in AGN jets. (Hovatta+, 2012)J/A+A/545/A113 : MOJAVE IX. Core shift effects (Pushkarev+, 2012)J/AJ/137/3718 : 15GHz monitoring of AGN jets with VLBA (Lister+, 2009)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/147/143https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/147/143http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/147/143https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/147/143https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/147/143http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/147/143GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/147/143/table1 (Sources and their spectral index properties)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/147/143/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/147/143/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/147/143/table1?GETtext/xml+votable180.050000true1.5578869-6.39314860.0055555555555555566/18 556 579 700 911 1085 1263 1450 1509 1546 1701 1702 2143 2214 2414 2721 2836 3024 3096 3309 3675 3820 3886 4054 4572 4695 4770 4820 5353 5423 5693 5767 5848 6252 6507 6641 6751 6853 6948 6984 7389 7570 7896 7969 8031 8220 8299 8487 8717 9347 9442 9460 9612 9632 9633 9676 9723 10163 10249 10321 10422 10548 11430 11639 11715 12047 12241 12352 12580 12604 12619 13156 13230 13352 13496 13693 13927 14520 14737 14744 15023 15067 15286 15494 15936 16027 16059 16093 16184 16298 16301 17184 17351 17579 17857 18035 18037 18378 18506 18624 18661 18669 18718 19088 19101 19190 19271 19398 19567 19593 19831 20099 20224 20468 20935 21266 21358 21564 21758 21768 21935 21960 21968 21972 22363 22375 22396 22658 22917 22950 23099 23121 23127 23323 23416 23691 24084 24571 25016 25196 25255 25302 25630 25742 25864 26115 26131 26292 26303 26491 26614 26900 26966 27060 27310 27417 27423 27765 28083 28479 28492 29016 29570 29675 29714 31190 31391 31399 31430 31451 31559 31664 31894 32660 32764 36188 36785 40527 40730 40762 44247 44805 44908 45011 48595 48610 48798 48846 48965 49071https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/147/143?format=asciiOpticalRadiodefaultJ/AJ/147/143/table1Sources and their spectral index propertiesSimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameSource IAU name (HHMM+DDd, B1950)meta.id;meta.maincharprimaryNoNumber of observations for this sourcemeta.numberintnullableONameOther known namemeta.idcharz[0/3.4]? Redshiftsrc.redshiftfloatnullableO[QGBU] Optical classification (1)src.classcharbeta? Maximum apparent speed in light speed units (2)phys.veloc;arith.difffloatnullableObsDateDate of spectral index observationtime.epochnullableNcNumber of components observed for this source at ObsDatemeta.numberintnullablealpha1? Spectral index {alpha} in the core componentspect.indexfloatnullablealpha2? Spectral index {alpha} in the median jet ridge linespect.index;stat.medianfloatnullableA[Y] Y if 2D cross-correlation not possible for image alignment (see Section 2.2 for details)meta.codecharpPDisplay the data from the previous papers (I, II, III, V, VI, VIII, and X)meta.numberintnullablep7Display the data from Paper VII (Homan et al. 2009, cat. J/ApJ/706/1253)meta.numberintnullablep9Display the data from Paper IX (Pushkarev et al. 2012, cat. J/A+A/545/A113)meta.numberintnullable_RAPositions from SIMBAD database (right ascension part)degpos.eq.ra;meta.main_DEPositions from SIMBAD database (declination part)degpos.eq.dec;meta.mainJ/AJ/147/143/table2Fitted gaussian components at 15.4GHz and their spectral index valuesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameSource IAU name (HHMM+DDd, B1950)meta.id;meta.maincharm_Name[0/46] Component number (0=core)meta.code.multipintObsDateDate of spectral index observationtime.epochnullabler[0/67] Component distance from phase center of intensity mapmaspos;arith.difffloatPA[-180/180] Position angle of the component from phase centerdegpos.posAngfloatalpha[-2.9-3.6] Spectral index of the componentspect.indexfloate_alpha[0.1/0.5] Uncertainty in alphastat.error;pos.eq.rafloatAge? Age of the component (1)yrtime.agefloatnullableFpol[0/25]? Fractional polarization of the component%phys.polarizationfloatnullablee_Fpol[0/6]? Uncertainty in FPol%stat.errorfloatnullableEVPA[-180/180]? Faraday-corrected electric vector position angle of the componentdegpos.posAng;phys.polarizationfloatnullablee_EVPA? Uncertainty in EVPAdegstat.errorfloatnullableB[Y] Indicates whether a jet component is at least one beam size away from the coremeta.codechar