J/A+A/588/A114ivo://CDS.VizieR/J/A+A/588/A114doi:10.26093/cds/vizier.35880114CDSBerkhuijsen E.M.Urbanik M.Beck R.Han J.L.2016-03-29T05:08:49Z2016-03-29T06:07:44ZCDS support team

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

cds-question@unistra.frgalaxiesmagnetic-fieldsradio-sourcesWe observed total and polarized radio continuum emission from the spiral galaxy M 101 at {lambda}{lambda}6.2cm and 11.1cm with the Effelsberg telescope. The angular resolutions are 2.5' (=5.4kpc) and 4.4' (=9.5kpc), respectively. We use these data to study various emission components in M 101 and properties of the magnetic field. Separation of thermal and non-thermal emission shows that the thermal emission is closely correlated with the spiral arms, while the non-thermal emission is more smoothly distributed indicating di ff usion of cosmic ray electrons away from their places of origin. The radial distribution of both emissions has a break near R=16kpc (=7.4'), where it steepens to an exponential scale length of L=~5kpc, which is about 2.5 times smaller than at R<16kpc. The distribution of the polarized emission has a broad maximum near R=12kpc and beyond R=16kpc also decreases with L=~5kpc. It seems that near R=16kpc a major change in the structure of M 101 takes place, which also a ff ects the distributions of the strength of the random and ordered magnetic field. Beyond R=16kpc the radial scale length of both fields is about 20kpc, which implies that they decrease to about 0.3uG at R=70kpc, which is the largest optical extent. The equipartition strength of the total field ranges from nearly 10uG at R<2kpc to 4uG at R=22-24kpc. As the random field dominates in M 101 (B_ran_/B_ord_=~2.4), wavelength-independent polarization is the main polarization mechanism. We show that energetic events causing H i shells of mean diameter <625pc could partly be responsible for this. At radii <24kpc, the random magnetic field depends on the star formation rate/area, {Sigma}_SFR_, with a power-law exponent of b=0.28+/-0.02. The ordered magnetic field is generally aligned with the spiral arms with pitch angles that are about 8{deg} larger than those of HI filaments.2016A&A...588A.114Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/588/A114CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/588/A114https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/588/A114http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/588/A114https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/588/A114https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/588/A114http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/588/A114GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/588/A114/list (List of fits images)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/588/A114/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/588/A114/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/588/A114/list?GETtext/xml+votable180.050000true210.3625654.588890.0055555555555555566/11434https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/588/A114?format=asciiRadiodefaultJ/A+A/588/A114/listList of fits imagesrecnoRecord 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 datetime.epoch;obsnullableFreq? Observed frequencyHzem.freqdoublenullablesizeSize of FITS fileKibytephys.size;meta.fitsintFileNameName of FITS file, in subdirectory fitsmeta.id;meta.fitscharTitleTitle of the FITS filemeta.title;meta.fitschar