Planck intermediate results: XLIV. Structure of the Galactic magnetic field from dust polarization maps of the southern Galactic cap

• Published in: Astronomy & Astrophysics
• Main Authors: Aghanim, N., Alves, M. I R, Arzoumanian, D., Aumont, J., Baccigalupi, C., Ballardini, M., Banday, A. J., Barreiro, R. B., Bartolo, N., Basak, S., Benabed, K., Bernard, J. P., Bersanelli, M., Bielewicz, P., Bonavera, L., Bond, J. R., Borrill, J., Bouchet, F. R., Boulanger, F., Bracco, A., Bucher, M., Burigana, C., Calabrese, E., Cardoso, J. F., Chiang, H. C., Colombo, L. P L, Combet, C., Comis, B., Couchot, F., Coulais, A., Crill, B. P., Curto, A., Cuttaia, F., Davis, R. J., De Bernardis, P., De Rosa, A., De Zotti, G., Delabrouille, J., Delouis, J. M., Di Valentino, E., Dickinson, C., Diego, J. M., Doré, O., Douspis, M., Ducout, A., Dupac, X., Dusini, S., Efstathiou, G., Elsner, F., Enßlin, T. A., Eriksen, H. K., Falgarone, E., Fantaye, Y., Ferrière, K., Finelli, F., Frailis, M., Fraisse, A. A., Franceschi, E., Frolov, A., Galeotta, S., Galli, S., Ganga, K., Génova-Santos, R. T., Gerbino, M., Ghosh, T., González-Nuevo, J., Górski, K. M., Gratton, S., Gregorio, A., Gruppuso, A., Gudmundsson, J. E., Guillet, V., Hansen, F. K., Helou, G., Henrot-Versillé, S., Herranz, D., Hivon, E., Huang, Z., Jaffe, A. H., Jaffe, T. R., Jones, W. C., Keihänen, E., Keskitalo, R., Kisner, T. S., Krachmalnicoff, N., Kunz, M., Kurki-Suonio, H., Lagache, G., Lähteenmäki, A., Lamarre, J. M., Langer, M., Lasenby, A., Lattanzi, M., Le Jeune, M., Levrier, F., Liguori, M., Lilje, P. B., López-Caniego, M., Lubin, P. M., MacIás-Pérez, J. F., Maggio, G., Maino, D., Mandolesi, N., Mangilli, A., Maris, M., Martin, P. G., Martínez-González, E., Matarrese, S., Mauri, N., McEwen, J. D., Melchiorri, A., Mennella, A., Migliaccio, M., Miville-Deschênes, M. A., Molinari, D., Moneti, A., Montier, L., Morgante, G., Moss, A., Naselsky, P., Natoli, P., Neveu, J., Nørgaard-Nielsen, H. U., Oppermann, N., Oxborrow, C. A., Pagano, L., Paoletti, D., Partridge, B., Perdereau, O., Perotto, L., Pettorino, V., Piacentini, F., Plaszczynski, S., Polenta, G., Rachen, J. P., Rebolo, R., Reinecke, M., Remazeilles, M., Renzi, A., Ristorcelli, I., Rocha, G., Rossetti, M., Roudier, G., Ruiz-Granados, B., Salvati, L., Sandri, M., Savelainen, M., Scott, D., Sirignano, C., Soler, J. D., Suur-Uski, A. S., Tauber, J. A., Tavagnacco, D., Tenti, M., Toffolatti, L., Tomasi, M., Tristram, M., Trombetti, T., Valiviita, J., Vansyngel, F., Van Tent, F., Vielva, P., Villa, F., Wandelt, B. D., Wehus, I. K., Zacchei, A., Zonca, A.
• Other Authors: Metsähovi Radio Observatory, Department of Electronics and Nanoengineering, Anne Lähteenmäki Group, Institut national de physique nucléaire et de physique des particules, IRAP, Service d'Astrophysique CEA, International School for Advanced Studies, Sapienza University of Rome, Universidad de Cantabria, UMR 7095, Istituto Nazionale di Astrofisica (INAF), University of Toronto, University of California, Berkeley, Institut d 'Astrophysique de Paris, Université Pierre et Marie Curie, University of Oxford, Telecom ParisTech, Princeton University, Jet Propulsion Laboratory, Université Paris-Sud, LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres, Kavli Institute for Cosmology Cambridge, Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna, Università La Sapienza, University of Manchester, Centre National de la Recherche Scientifique (CNRS), Urbanización Villafranca Del Castillo, University of Cambridge, Max-Planck-Institut für Astrophysik, University of Oslo, Università degli Studi di Roma Tor Vergata, Osservatorio Astronomico di Trieste, Simon Fraser University, University of Chicago, Instituto de Astrofísica de Canarias, Stockholm University, University of Warsaw, California Institute of Technology, Imperial College London, University of Helsinki, Lawrence Berkeley National Laboratory, University of Milan, University of California, Santa Barbara, University College London, University of Nottingham, Niels Bohr Institute, Danmarks Tekniske Universitet, Haverford College, Institut für Theoretische Astrophysik, Osservatorio Astronomico di Roma
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2016
• Subjects: Cosmic background radiation; Dust; extinction; ISM: magnetic fields; Magnetohydrodynamics (MHD); Methods: data analysis; Polarization; South pole
• Online Access: https://aaltodoc.aalto.fi/handle/123456789/25009; https://doi.org/10.1051/0004-6361/201628636

Using data from the Planck satellite, we study the statistical properties of interstellar dust polarization at high Galactic latitudes around the south pole (b <-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, Q, and U maps at 353 GHz, and particularly the statistical distribution of the polarization fraction (p) and angle (ψ), in order to characterize the ordered and turbulent components of the Galactic magnetic field (GMF) in the solar neighbourhood. The Q and U maps show patterns at large angular scales, which we relate to the mean orientation of the GMF towards Galactic coordinates (l0,b0) = (70° ± 5°,24° ± 5°). The histogram of the observed p values shows a wide dispersion up to 25%. The histogram of ψ 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 p and ψ to a statistical description of the turbulent component of the GMF, assuming a uniform effective polarization fraction (p0) 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 N 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 p and ψ distributions using a p0 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 N. The mean value of p (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 ...