J/A+A/651/A98ivo://CDS.VizieR/J/A+A/651/A98doi:10.26093/cds/vizier.36510098CDSFatigoni S.Radiconi F.Battistelli E.S.Murgia M.Carretti E.,Castangia P.Concu R.de Bernardis P.Fritz J.Genova-Santos R.,Govoni F.Guidi F.Lamagna L.Masi S.Melis A.Paladini R.,Perez-Toledo F.M.Piacentini F.Poppi S.Rebolo R.Rubino-Martin J.A.,Surcis G.Tarchi A.Vacca V.2022-01-17T11:45:00Z2021-07-24T19:21:14ZCDS support team

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

cds-question@unistra.frgalaxiesradio-galaxiesradio-continuum-emissionmillimeter-astronomysubmillimeter-astronomyThe Andromeda galaxy is the best known large galaxy besides our own Milky Way. Several images and studies exist at all wavelengths from radio to hard X-ray. Nevertheless, only few observations are available in the microwave range where its average radio emission reaches the minimum. In this paper we want to study the radio morphology of the galaxy, decouple thermal from non-thermal emission and extract the star formation rate. We also aim to derive a complete catalogue of radio sources for the mapped patch of sky. We have observed the Andromeda galaxy with the Sardinia Radio Telescope at 6.6 GHz with very high sensitivity and angular resolution, and an unprecedented sky coverage. Using new 6.6GHz data and Effelsberg radio telescope ancillary data, we confirm that, globally, the spectral index assumes a value of ~0.7-0.8, while in the star forming regions it decreases to ~0.5. By disentangling (gas) thermal and non-thermal emission, we found that at 6.6GHz, thermal emission follows the distribution of HII regions around the ring. Non-thermal emission, within the ring, appears to be more uniform and smooth than thermal emission, due to the diffusion of the cosmic ray electrons away from their birthplaces. Hence the magnetic fields are nearly constant in intensity. Based on the thermal emission map, we have calculated a star formation rate map. Integrating within a radius of R_max_=15kpc, we obtained a total star formation rate of 0.19+/-0.01M*/yr in agreement with previous results in literature. Finally, we correlated our radio data with Infrared images of the Andromeda galaxy. We found an unexpected high correlation between non-thermal and MIR data in the central region, with a correlation parameter r=0.93. Finally, by computing the logarithmic 24um/21cm ratio q_24um_, we found a decreasing trend with increasing galactocentric distance and an increasing dispersion. The logarithmic FIR/radio ratio is found to be 2.41+/-0.04.2021A&A...651A..98Fhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/651/A98CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/651/A98https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/651/A98http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/651/A98https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/651/A98https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/651/A98http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/651/A98GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/651/A98/tablea1 (Catalogue of point sources)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/651/A98/tablea1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/651/A98/tablea1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/651/A98/tablea1?GETtext/xml+votable180.050000true10.5740.160.005555555555555556Cone search capability for table J/A+A/651/A98/list (Information on fits image)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/651/A98/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/651/A98/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/651/A98/list?GETtext/xml+votable180.050000true10.707541.28750.005555555555555556Associated datahttps://cdsarc.cds.unistra.fr/assocdata/?obs_collection=J/A+A/651/A985/677 6/2619 2621-2623 2666-2667 2705 2752-27534.373205853212163e-24 4.373205853212163e-24https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/651/A98?format=asciiMillimeterRadiodefaultJ/A+A/651/A98/tablea1Catalogue of point sourcesClassNED Object Classmeta.code.classcharNSource identification numbermeta.id;meta.mainintNObjNearest NED objectmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right Ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainF6.6GHzFlux Density at 6.6GHzJyphot.flux.density;em.radio.6-12GHzfloate_F6.6GHzFlux Density at 6.6GHz ErrorJystat.errorfloatAModel Amplitudesrc.var.amplitude;meta.modelledfloatalphaModModel 'spectral index'spect.index;meta.modelledfloatkModel curvaturestat.paramfloatalphaMeasured spectral index, alpha_1.4GHz_^6.6GHz^spect.indexfloatJ/A+A/651/A98/listInformation on fits imageTitleTitle of the FITS filemeta.title;meta.fitscharrecnoRecord 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.numberintFreqObserved frequencyGHzem.freqdoublesizeSize of FITS fileKibytephys.size;meta.fitsintFileNameName of FITS file, in subdirectory fitsmeta.id;meta.fitscharAssocDataAssociated Data web pagemeta.ref.urlchar