J/MNRAS/508/3921ivo://CDS.VizieR/J/MNRAS/508/3921doi:10.26093/cds/vizier.75083921CDSJung S.L.Mcclure-griffiths N.M.Hill A.S.2024-11-29T20:16:40Z2024-09-17T12:37:33ZCDS support team

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

cds-question@unistra.frmagellanic-cloudsdiffuse-molecular-cloudsmilky-way-galaxyradio-sourcessupernova-remnantsmagnetic-fieldsastrometryphotometryFaraday rotation measures (RMs) should be interpreted with caution because there could be multiple magneto-ionized medium components that contribute to the net Faraday rotation along sightlines. We introduce a simple test using Galactic diffuse polarized emission that evaluates whether structures evident in RM observations are associated with distant circumgalactic medium or foreground interstellar medium. We focus on the Magellanic Leading Arm region where a clear excess of RM was previously reported. There are two gaseous objects standing out in this direction: the distant Magellanic Leading Arm and the nearby Antlia supernova remnant (SNR). We recognized narrow depolarized filaments in the 2.3 GHz S-band Polarization All Sky Survey image that overlaps with the reported RM excess. We suggest that there is a steep gradient in Faraday rotation in a foreground screen arising from the Antlia SNR. The estimated strength of the line-of-sight component of the magnetic field is B_||_~5{mu}G, assuming that the excess of RM is entirely an outcome of the magnetized supernova shell. Our analysis indicates that the overlap between the RM excess and the Magellanic Leading Arm is only a remarkable coincidence. We suggest for future RM grid studies that checking Galactic diffuse polarization maps is a convenient way to identify local Faraday screens.2021MNRAS.508.3921Jhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/508/3921CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/MNRAS/467/1776 : Faraday rotation in Magellanic Bridge (Kaczmarek+, 2017)J/ApJ/871/215 : JVLA rotation measures of Smith cloud bckg sourcesVIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)J/ApJ/702/1230 : Rotation measure image of the sky (Taylor+, 2009)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/508/3921https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/508/3921http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/508/3921https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/508/3921https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/508/3921http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/508/3921GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/508/3921/tablea1 (Our polarized sources observed using ATCA matching our criteria)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/508/3921/tablea1?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/508/3921/tablea1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/508/3921/tablea1?GETtext/xml+votable180.050000true170.345417-43.9271940.0055555555555555560/https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/508/3921?format=asciiRadiodefaultJ/MNRAS/508/3921/tablea1Our polarized sources observed using ATCA matching our criteriarecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainGLONGalactic longitude (l)degpos.galactic.lonGLATGalactic latitude (b)degpos.galactic.latfloatSIFlux density per beam area in the S-band polarized in Stokes I (S_I_) (1)Jy/beamphot.flux.density;em.radio.1500-3000MHzfloate_SIMean error on S_I_ (S_Ierr_)Jy/beamstat.errorfloatpPolarized surface brightness per beam area (p) (2)Jy/beamphot.mag.sbfloate_pMean error on p (p_err_)Jy/beamstat.errorfloatphiThe Faraday depth {phi} ({phi}) (3)rad.m**-2phys.polarization.rotMeasurefloate_phiMean error on {phi} ({phi}_err_)rad.m**-2stat.errorfloat