Lenc, E.E.LencGaensler, B. M.B. M.GaenslerSun, X. H.X. H.SunSadler, E. M.E. M.SadlerWillis, A. G.A. G.WillisBarry, N.N.BarryBeardsley, A. P.A. P.BeardsleyBell, M. E.M. E.BellBERNARDI, GIANNIGIANNIBERNARDIBowman, J. D.J. D.BowmanBriggs, F.F.BriggsCallingham, J. R.J. R.CallinghamCappallo, R. J.R. J.CappalloCarroll, P.P.CarrollCorey, B. E.B. E.Coreyde Oliveira-Costa, A.A.de Oliveira-CostaDeshpande, A. A.A. A.DeshpandeDillon, J. S.J. S.DillonDwarkanath, K. S.K. S.DwarkanathEmrich, D.D.EmrichEwall-Wice, A.A.Ewall-WiceFeng, L.L.FengFor, B. -Q.B. -Q.ForGoeke, R.R.GoekeGreenhill, L. J.L. J.GreenhillHancock, P.P.HancockHazelton, B. J.B. J.HazeltonHewitt, J. N.J. N.HewittHindson, L.L.HindsonHurley-Walker, N.N.Hurley-WalkerJohnston-Hollitt, M.M.Johnston-HollittJacobs, D. C.D. C.JacobsKapińska, A. D.A. D.KapińskaKaplan, D. L.D. L.KaplanKasper, J. C.J. C.KasperKim, H. -S.H. -S.KimKratzenberg, E.E.KratzenbergLine, J.J.LineLoeb, A.A.LoebLonsdale, C. J.C. J.LonsdaleLynch, M. J.M. J.LynchMcKinley, B.B.McKinleyMcWhirter, S. R.S. R.McWhirterMitchell, D. A.D. A.MitchellMorales, M. F.M. F.MoralesMorgan, E.E.MorganMorgan, J.J.MorganMurphy, T.T.MurphyNeben, A. R.A. R.NebenOberoi, D.D.OberoiOffringa, A. R.A. R.OffringaOrd, S. M.S. M.OrdPaul, S.S.PaulPindor, B.B.PindorPober, J. C.J. C.PoberPrabu, T.T.PrabuProcopio, P.P.ProcopioRiding, J.J.RidingRogers, A. E. E.A. E. E.RogersRoshi, A.A.RoshiUdaya Shankar, N.N.Udaya ShankarSethi, S. K.S. K.SethiSrivani, K. S.K. S.SrivaniStaveley-Smith, L.L.Staveley-SmithSubrahmanyan, R.R.SubrahmanyanSullivan, I. S.I. S.SullivanTegmark, M.M.TegmarkThyagarajan, NithyanandanNithyanandanThyagarajanTingay, S. J.S. J.TingayTrott, C.C.TrottWaterson, M.M.WatersonWayth, R. B.R. B.WaythWebster, R. L.R. L.WebsterWhitney, A. R.A. R.WhitneyWilliams, A.A.WilliamsWilliams, C. L.C. L.WilliamsWu, C.C.WuWyithe, J. S. B.J. S. B.WyitheZheng, Q.Q.Zheng2020-07-032020-07-0320160004-637Xhttp://hdl.handle.net/20.500.12386/26312We present deep polarimetric observations at 154 MHz with the Murchison Widefield Array (MWA), covering 625 deg<SUP>2</SUP> centered on α = 0<SUP>h</SUP>and δ = -27°. The sensitivity available in our deep observations allows an in-band, frequency-dependent analysis of polarized structure for the first time at long wavelengths. Our analysis suggests that the polarized structures are dominated by intrinsic emission but may also have a foreground Faraday screen component. At these wavelengths, the compactness of the MWA baseline distribution provides excellent snapshot sensitivity to large-scale structure. The observations are sensitive to diffuse polarized emission at ∼54′ resolution with a sensitivity of 5.9 mJy beam<SUP>-1</SUP> and compact polarized sources at ∼2.′4 resolution with a sensitivity of 2.3 mJy beam<SUP>-1</SUP> for a subset (400 deg<SUP>2</SUP>) of this field. The sensitivity allows the effect of ionospheric Faraday rotation to be spatially and temporally measured directly from the diffuse polarized background. Our observations reveal large-scale structures (∼1°-8° in extent) in linear polarization clearly detectable in ∼2 minute snapshots, which would remain undetectable by interferometers with minimum baseline lengths of >110 m at 154 MHz. The brightness temperature of these structures is on average 4 K in polarized intensity, peaking at 11 K. Rotation measure synthesis reveals that the structures have Faraday depths ranging from -2 to 10 rad m<SUP>-2</SUP> with a large fraction peaking at approximately +1 rad m<SUP>-2</SUP>. We estimate a distance of 51 ± 20 pc to the polarized emission based on measurements of the in-field pulsar J2330-2005. We detect four extragalactic linearly polarized point sources within the field in our compact source survey. Based on the known polarized source population at 1.4 GHz and non-detections at 154 MHz, we estimate an upper limit on the depolarization ratio of 0.08 from 1.4 GHz to 154 MHz.STAMPAenArticle10.3847/0004-637X/830/1/382-s2.0-84990984030000400462400001https://iopscience.iop.org/article/10.3847/0004-637X/830/1/382016ApJ...830...38LFIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering