J/A+A/632/A12ivo://CDS.VizieR/J/A+A/632/A12doi:10.26093/cds/vizier.36320012CDSSchmidt P.Krause M.Heesen V.Basu A.Beck R.Wiegert T.Irwin J.A.,Heald G.Rand R.J.Li J.-T.Murphy E.J.2020-04-06T14:56:13Z2019-11-26T08:21:36ZCDS support team

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

cds-question@unistra.frgalaxiesradio-continuum-emissionmagnetic-fieldsCosmic-ray electrons (CREs) originating from the star-forming discs of spiral galaxies frequently form extended radio haloes that are best observable in edge-on galaxies, where their properties can be directly investigated as a function of vertical height above the disc. For the present study, we selected two nearby edge-on galaxies from the Continuum Halos in Nearby Galaxies - an EVLA Survey (CHANG-ES), NGC 891 and 4565, which differ largely in their detectable halo extent and their star- formation rates (SFRs). Our aim is to figure out how such differences are related to the (advective and/or diffusive) CRE transport in the disc and in the halo. We use wide-band 1.5 and 6GHz Very Large Array (VLA) observations obtained in the B, C, and D configurations, and combine the 6GHz images with Effelsberg observations to correct for missing short spacings. After subtraction of the thermal emission, we investigate the spatially resolved synchrotron spectral index distribution in terms of CRE spectral ageing. We further compute total magnetic field strengths assuming equipartition between the cosmic-ray (CR) energy density and the magnetic field, and measure synchrotron scale heights at both frequencies. Based on the fitted vertical profiles of the synchrotron intensity and on the spectral index profile between 1.5 and 6GHz, we create purely advective and purely diffusive CRE transport models by numerically solving the 1D diffusion-loss equation. In particular, we investigate for the first time the radial dependence of synchrotron and magnetic field scale heights, advection speeds, and diffusion coefficients, whereas previous studies of these two galaxies only determined global values of these quantities.2019A&A...632A..12Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/632/A12CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/623/A33 : NGC 4666 polarization maps (Stein+, 2019)J/A+A/632/A10 : NGC 4631 total intensity images (Mora-Partiarroyo+, 2019)J/A+A/632/A11 : Radio images of NGC 4631 (Mora-Partiarroyo+, 2019)J/A+A/632/A13 : NGC 4013 radio and polarization map (Stein+, 2019)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/632/A12https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/632/A12http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/632/A12https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/632/A12https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/632/A12http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/632/A12GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/632/A12/list (List of FITS files)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/632/A12/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/632/A12/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/632/A12/list?GETtext/xml+votable180.050000true35.6388642.348790.0055555555555555566/2409 28141https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/632/A12?format=asciiRadiodefaultJ/A+A/632/A12/listList of FITS filesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right Ascension of center (J2000)degpos.eq.ra;meta.mainDEJ2000Declination of center (J2000)degpos.eq.dec;meta.mainNxNumber of pixels along X-axismeta.numberintNyNumber of pixels along Y-axismeta.numberintObs.dateObservation datestime.epoch;obsnullableFreq? Observed frequencyGHzem.freqdoublenullableUnitsMap unitsmeta.unitcharFWHMAngular resolution, referred to as the full width at half maximum (FWHM) of the circular synthesized beamarcsecpos.angResolutionfloatsizeSize of FITS fileKibytephys.size;meta.fitsintFileNameName of FITS file, in subdirectory fitsmeta.id;meta.fitscharTitleTitle of the FITS filemeta.title;meta.fitschar