Planck intermediate results: XLIV. Structure of the Galactic magnetic field from dust polarization maps of the southern Galactic cap
Articolo
Data di Pubblicazione:
2016
Abstract:
We study the statistical properties of interstellar dust polarization at high Galactic latitude, using the Stokes parameter Planck maps at 353 GHz. Our aim is to advance the understanding of the magnetized interstellar medium (ISM), and to provide a model of the polarized dust foreground for cosmic microwave background component-separation procedures. Focusing on the southern Galactic cap, we examine the statistical distributions of the polarization fraction (p ) and angle (ψ ) to characterize the ordered and turbulent components of the Galactic magnetic field (GMF) in the solar neighbourhood. We relate patterns at large angular scales in polarization to the orientation of the mean (ordered) GMF towards Galactic coordinates (l 0 ,b 0 )=(70 ∘ ±5 ∘ ,24 ∘ ±5 ∘ ) . The histogram of p 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 use these histograms to build a phenomenological model of the turbulent component of the GMF, assuming a uniform effective polarization fraction (p 0 ) of dust emission. To model 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 p 0 value of (26 ± 3)%; a ratio of 0.9 ± 0.1 between the strengths of the turbulent and mean components of the GMF; and a small value of N . We relate the polarization layers to the density structure and to the correlation length of the GMF along the LOS.
Tipologia CRIS:
01.01 - Articolo in rivista
Keywords:
Cosmic background radiation; Dust, extinction; ISM: magnetic fields; Magnetohydrodynamics (MHD); Methods: data analysis; Polarization; Astronomy and Astrophysics; Space and Planetary Science
Elenco autori:
Aghanim, N.; Alves, M. I. R.; Arzoumanian, D.; Aumont, J.; Baccigalupi, C.; Ballardini, M.; Banday, A. J.; Barreiro, R. B.; Bartolo, Nicola; 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, Stefano; 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, Michele; 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, Sabino; 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, Alessandro; Ristorcelli, I.; Rocha, G.; Rossetti, M.; Roudier, G.; Ruiz Granados, B.; Salvati, L.; Sandri, M.; Savelainen, M.; Scott, D.; Sirignano, Chiara; 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.
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