Planck intermediate results: XLIV. Structure of the Galactic magnetic field from dust polarization maps of the southern Galactic cap
Using data from the <i>Planck<i/> satellite, we study the statistical properties of interstellar dust polarization at high Galactic latitudes around the south pole (<i>b<i/> < −60°). Our aim is to advance the understanding of the magnetized interstellar medium (ISM), and t...
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| Main Authors: | , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
12 December 2016
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| In: |
Astronomy and astrophysics
Year: 2016, Volume: 596, Pages: 1-15 |
| ISSN: | 1432-0746 |
| DOI: | 10.1051/0004-6361/201628636 |
| Online Access: | Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1051/0004-6361/201628636 Verlag, lizenzpflichtig, Volltext: https://www.aanda.org/articles/aa/abs/2016/12/aa28636-16/aa28636-16.html 
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| Author Notes: | Planck Collaboration: N. Aghanim, M.I.R. Alves, D. Arzoumanian, J. Aumont, C. Baccigalupi, M. Ballardini, A.J. Banday, R.B. Barreiro, N. Bartolo, S. Basak, K. Benabed, J.-P. Bernard, M. Bersanelli, P. Bielewicz, L. Bonavera, J.R. Bond, J. Borrill, F.R. Bouchet, F. Boulanger, A. Bracco, M. Bucher, C. Burigana, E. Calabrese, J.-F. Cardoso, H.C. Chiang, L.P.L. Colombo, C. Combet, B. Comis, F. Couchot, A. Coulais, B.P. Crill, A. Curto, F. Cuttaia, R.J. Davis, P. de Bernardis, A. de Rosa, G. de Zotti, J. Delabrouille, J.-M. Delouis, E. Di Valentino, C. Dickinson, J. M. Diego, O. Doré, M. Douspis, A. Ducout, X. Dupac, S. Dusini, G. Efstathiou, F. Elsner, T.A. Enßlin, H.K. Eriksen, E. Falgarone, Y. Fantaye, K. Ferrière, F. Finelli, M. Frailis, A.A. Fraisse, E. Franceschi, A. Frolov, S. Galeotta, S. Galli, K. Ganga, R.T. Génova-Santos, M. Gerbino, T. Ghosh, J. González-Nuevo, K.M. Górski, S. Gratton, A. Gregorio, A. Gruppuso, J.E. Gudmundsson, V. Guillet, F.K. Hansen, G. Helou, S. Henrot-Versillé, D. Herranz, E. Hivon, Z. Huang, A.H. Jaffe, T. R. Jaffe, W.C. Jones, E. Keihänen, R. Keskitalo, T.S. Kisner, N. Krachmalnicoff, M. Kunz, H. Kurki-Suonio, G. Lagache, A. Lähteenmäki, J.-M. Lamarre, M. Langer, A. Lasenby, M. Lattanzi, M. Le Jeune, F. Levrier, M. Liguori, P.B. Lilje, M. López-Caniego, P.M. Lubin, J.F. Macías-Pérez, G. Maggio, D. Maino, N. Mandolesi, A. Mangilli, M. Maris, P.G. Martin, E. Martínez-González, S. Matarrese, N. Mauri, J.D. McEwen, A. Melchiorri, A. Mennella, M. Migliaccio, M.-A. Miville-Deschênes, D. Molinari, A. Moneti, L. Montier, G. Morgante, A. Moss, P. Naselsky, P. Natoli, J. Neveu, H.U. Nørgaard-Nielsen, N. Oppermann, C.A. Oxborrow, L. Pagano, D. Paoletti, B. Partridge, O. Perdereau, L. Perotto, V. Pettorino, F. Piacentini, S. Plaszczynski, G. Polenta, J.P. Rachen, R. Rebolo, M. Reinecke, M. Remazeilles, A. Renzi, I. Ristorcelli, G. Rocha, M. Rossetti, G. Roudier, B. Ruiz-Granados, L. Salvati, M. Sandri, M. Savelainen, D. Scott, C. Sirignano, J.D. Soler, A.-S. Suur-Uski, J.A. Tauber, D. Tavagnacco, M. Tenti, L. Toffolatti, M. Tomasi, M. Tristram, T. Trombetti, J. Valiviita, F. Vansyngel, F. Van Tent, P. Vielva, F. Villa, B.D. Wandelt, I.K. Wehus, A. Zacchei, and A. Zonca |
| Summary: | Using data from the <i>Planck<i/> satellite, we study the statistical properties of interstellar dust polarization at high Galactic latitudes around the south pole (<i>b<i/> < −60°). Our aim is to advance the understanding of the magnetized interstellar medium (ISM), and to provide a modelling framework of the polarized dust foreground for use in cosmic microwave background (CMB) component-separation procedures. We examine the Stokes <i>I<i/>, <i>Q<i/>, and <i>U<i/> maps at 353 GHz, and particularly the statistical distribution of the polarization fraction (<i>p<i/>) and angle (<i>ψ<i/>), in order to characterize the ordered and turbulent components of the Galactic magnetic field (GMF) in the solar neighbourhood. The <i>Q<i/> and <i>U<i/> maps show patterns at large angular scales, which we relate to the mean orientation of the GMF towards Galactic coordinates (<i>l<i/><sub>0<sub/>,<i>b<i/><sub>0<sub/>) = (70° ± 5°,24° ± 5°). The histogram of the observed <i>p<i/> values shows a wide dispersion up to 25%. The histogram of <i>ψ<i/> has a standard deviation of 12° about the regular pattern expected from the ordered GMF. We build a phenomenological model that connects the distributions of <i>p<i/> and <i>ψ<i/> to a statistical description of the turbulent component of the GMF, assuming a uniform effective polarization fraction (<i>p<i/><sub>0<sub/>) of dust emission. To compute the Stokes parameters, we approximate the integration along the line of sight (LOS) as a sum over a set of <i>N<i/> independent polarization layers, in each of which the turbulent component of the GMF is obtained from Gaussian realizations of a power-law power spectrum. We are able to reproduce the observed <i>p<i/> and <i>ψ<i/> distributions using a <i>p<i/><sub>0<sub/> value of 26%, a ratio of 0.9 between the strengths of the turbulent and mean components of the GMF, and a small value of <i>N<i/>. The mean value of <i>p<i/> (inferred from the fit of the large-scale patterns in the Stokes maps) is 12 ± 1%. We relate the polarization layers to the density structure and to the correlation length of the GMF along the LOS. We emphasize the simplicity of our model (involving only a few parameters), which can be easily computed on the celestial sphere to produce simulated maps of dust polarization. Our work is an important step towards a model that can be used to assess the accuracy of component-separation methods in present and future CMB experiments designed to search the <i>B<i/> mode CMB polarization from primordial gravity waves. |
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| Item Description: | Gesehen am 10.08.2020 |
| Physical Description: | Online Resource |
| ISSN: | 1432-0746 |
| DOI: | 10.1051/0004-6361/201628636 |