J/A+A/705/A143ivo://CDS.VizieR/J/A+A/705/A143CDSAlonso-Lopez D.O'Sullivan S.P.Bonafede A.Boess L.M.Stuardi C.,Osinga E.Anderson C.S.Van Eck C.L.Carretti E.West J.L.Akahori T.,Dolag K.Giacintucci S.Khadir A.Ma Y.K.Malik S.,McClure-Griffiths N.Rudnick L.Seidel B.A.Tiwari S.Venturi T.2026-03-02T06:25:50Z2026-01-16T10:39:35ZCDS support team

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

cds-question@unistra.frgalaxy-clusterspolarimetrymagnetic-fieldsradio-sourcesFaraday rotation measure (RM) grids provide a sensitive means to trace magnetized plasma across a wide range of cosmic environments. We study the RM signal from the Shapley Supercluster core (SSC) in order to constrain the magnetic field properties of its gas. The SSC region consists of two galaxy clusters, A3558 and A3562, and two galaxy groups between them, at z=~0.048. We combined RM Grid data with thermal Sunyaev-Zeldovich effect data, obtained from the POlarisation Sky Survey of the Universe's Magnetism (POSSUM) pilot survey, and Planck, respectively. To robustly determine the gas density, its magnetic field properties, and their correlation |B|{prop.to}n_e_^eta^, we studied the RM scatter in the SSC region (G_RM_) and its behavior as a function of distance to the nearest cluster and/or group (d_nrst_). We compared observational results with semi-analytic Gaussian random field models and more realistic cosmological magnetohydrodynamical (MHD) simulations. With a sky-density of 36RMs/deg^2^, we detect an excess RM scatter of 30.5+/-4.6rad/m^2^ in the SSC region. When we compare with models, we find an average magnetic field strength of ~1-3 uG (in the groups and clusters). The G_RM_(dnrst) profile, derived from data ranging from ~0.3-1.8r500 for all objects, is systematically flatter than expected compared to the models, with eta<0.5 being favored. Despite this discrepancy, we find that cosmological MHD simulations matched to the SSC structure most closely align with scenarios where the magnetic field is amplified by the turbulent velocity (v_turb_) in the intercluster regions BF{prop.to}n_e_^1/2^*v_turb_ on scales d_nrst_<~0.8. The dense RM grid and precision provided by POSSUM allows us to probe magnetized gas in the SSC clusters and groups on scales within and beyond their r500. Flatter-than-expected RM scatter profiles reveal a significant challenge in reconciling observations with even the most realistic predictions from cosmological MHD simulations in the outskirts of interacting clusters.2026A&A...705A.143Ahttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/705/A143CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AJ/110/463 : Kinematics of the Shapley supercluster (Quintana+ 1995)J/AJ/130/2541 : Core of the Shapley supercluster at 1.4GHz (Miller+, 2005)J/A+A/445/819 : Systems of galaxies in Shapley supercluster (Ragone+, 2006)J/MNRAS/381/1035 : Spectroscopy in Shapley supercluster (Smith+, 2007)J/A+A/638/A27 : Redshift database towards Shapley Superclusterhttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/705/A143https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/705/A143http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/705/A143https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/705/A143https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/705/A143http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/705/A143GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/705/A143/rm-ssc (Polarised source catalog (RM Grid))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/705/A143/rm-ssc?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/705/A143/rm-ssc?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/705/A143/rm-ssc?GETtext/xml+votable180.050000true201.73130694-32.4244650.0055555555555555565/10959 6/43830-43831 43833 43835 43880 43882 43924https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/705/A143?format=asciiRadiodefaultJ/A+A/705/A143/rm-sscPolarised source catalog (RM Grid)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSBIDSBID identification (id_number_sourcefinder)meta.idcharNameUnique source identification, JHHMMSS+DDMMSS (component_name)meta.id;meta.maincharRAJ2000Right ascension (J2000) (ra)degpos.eq.ra;meta.mainDEJ2000Declination (J2000) (dec)degpos.eq.dec;meta.maine_RAJ2000? Right ascension error (err_ra)degstat.error;pos.eq.radoublenullablee_DEJ2000? Declination error (err_dec)degstat.error;pos.eq.decdoublenullableStokesIStokes I (stokesI)Jy/beamphys.polarization.stokesdoublee_StokesI? Stokes I error (err_stokesI)Jy/beamstat.errordoublenullableRMRotation Measure (RM)rad.m**-2phys.polarization.rotMeasuredoublee_RMRotation Measure error (err_RM)rad.m**-2stat.errordoublePolIntPolarised intensity (polint)Jy/beamphot.flux.densitydoublee_PolIntPolarised intensity error (err_polint)Jy/beamstat.errordoubleSNR-PISignal to noise ratio in polarisation (SNR_PI)stat.snrdoublePolAnglePolarisation angle (polangle)degpos.posAng;phys.polarizationdoublee_PolAnglePolarisation angle error (err_polangle)degstat.errordoubleDerotPolAnglePolarisation angle (intrinsic) (derot_polangle)degpos.posAng;phys.polarizationdoublee_DerotPolAnglePolarisation angle (intrinsic) error (err_derot_polangle)degstat.errordoublefracPolFractional polarisation (fracpol)stat.fit.paramdoubleBand[1/2] ASKAP-POSSUM Band 1/Band 2 (askap_possum_Band) (1)instr.bandpassintRRMResidual Rotation Measure (RRM)rad.m**-2stat.fit.residual;phys.polarization.rotMeasuredoublee_RRMResidual Rotation Measure error (err_RRM)rad.m**-2stat.errordoubleSubsampleSub-sample of sources: on/off target (subsample)meta.codechar