Planck 2018 results. XII. Galactic astrophysics using polarized dust emission
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Planck 2018 results. XII. Galactic astrophysics using polarized dust emission

  • Author(s): Collaboration, Planck
  • Aghanim, N
  • Akrami, Y
  • Alves, MIR
  • Ashdown, M
  • Aumont, J
  • Baccigalupi, C
  • Ballardini, M
  • Banday, AJ
  • Barreiro, RB
  • Bartolo, N
  • Basak, S
  • Benabed, K
  • Bernard, J-P
  • Bersanelli, M
  • Bielewicz, P
  • Bock, JJ
  • Bond, JR
  • Borrill, J
  • Bouchet, FR
  • Boulanger, F
  • Bracco, A
  • Bucher, M
  • Burigana, C
  • Calabrese, E
  • Cardoso, J-F
  • Carron, J
  • Chary, R-R
  • Chiang, HC
  • Colombo, LPL
  • Combet, C
  • Crill, BP
  • Cuttaia, F
  • Bernardis, P de
  • Zotti, G de
  • Delabrouille, J
  • Delouis, J-M
  • Valentino, E Di
  • Dickinson, C
  • Diego, JM
  • Doré, O
  • Douspis, M
  • Ducout, A
  • Dupac, X
  • Efstathiou, G
  • Elsner, F
  • Enßlin, TA
  • Eriksen, HK
  • Falgarone, E
  • Fantaye, Y
  • Fernandez-Cobos, R
  • Ferrière, K
  • Finelli, F
  • Forastieri, F
  • Frailis, M
  • Fraisse, AA
  • Franceschi, E
  • Frolov, A
  • Galeotta, S
  • Galli, S
  • Ganga, K
  • Génova-Santos, RT
  • Gerbino, M
  • Ghosh, T
  • González-Nuevo, J
  • Górski, KM
  • Gratton, S
  • Green, G
  • Gruppuso, A
  • Gudmundsson, JE
  • Guillet, V
  • Handley, W
  • Hansen, FK
  • Helou, G
  • Herranz, D
  • Hivon, E
  • Huang, Z
  • Jaffe, AH
  • Jones, WC
  • Keihänen, E
  • Keskitalo, R
  • Kiiveri, K
  • Kim, J
  • Krachmalnicoff, N
  • Kunz, M
  • Kurki-Suonio, H
  • Lagache, G
  • Lamarre, J-M
  • Lasenby, A
  • Lattanzi, M
  • Lawrence, CR
  • Jeune, M Le
  • Levrier, F
  • Liguori, M
  • Lilje, PB
  • Lindholm, V
  • López-Caniego, M
  • Lubin, PM
  • Ma, Y-Z
  • Macías-Pérez, JF
  • Maggio, G
  • Maino, D
  • Mandolesi, N
  • Mangilli, A
  • Marcos-Caballero, A
  • Maris, M
  • Martin, PG
  • Martínez-González, E
  • Matarrese, S
  • Mauri, N
  • McEwen, JD
  • Melchiorri, A
  • Mennella, A
  • Migliaccio, M
  • Miville-Deschênes, M-A
  • Molinari, D
  • Moneti, A
  • Montier, L
  • Morgante, G
  • Moss, A
  • Natoli, P
  • Pagano, L
  • Paoletti, D
  • Patanchon, G
  • Perrotta, F
  • Pettorino, V
  • Piacentini, F
  • Polastri, L
  • Polenta, G
  • Puget, J-L
  • Rachen, JP
  • Reinecke, M
  • Remazeilles, M
  • Renzi, A
  • Ristorcelli, I
  • Rocha, G
  • Rosset, C
  • Roudier, G
  • Rubiño-Martín, JA
  • Ruiz-Granados, B
  • Salvati, L
  • Sandri, M
  • Savelainen, M
  • Scott, D
  • Sirignano, C
  • Sunyaev, R
  • Suur-Uski, A-S
  • Tauber, JA
  • Tavagnacco, D
  • Tenti, M
  • Toffolatti, L
  • Tomasi, M
  • Trombetti, T
  • Valiviita, J
  • Vansyngel, F
  • Tent, B Van
  • Vielva, P
  • Villa, F
  • Vittorio, N
  • Wandelt, BD
  • Wehus, IK
  • Zacchei, A
  • Zonca, A
  • et al.
Abstract

We present 353 GHz full-sky maps of the polarization fraction $p$, angle $\psi$, and dispersion of angles $S$ of Galactic dust thermal emission produced from the 2018 release of Planck data. We confirm that the mean and maximum of $p$ decrease with increasing $N_H$. The uncertainty on the maximum polarization fraction, $p_\mathrm{max}=22.0$% at 80 arcmin resolution, is dominated by the uncertainty on the zero level in total intensity. The observed inverse behaviour between $p$ and $S$ is interpreted with models of the polarized sky that include effects from only the topology of the turbulent Galactic magnetic field. Thus, the statistical properties of $p$, $\psi$, and $S$ mostly reflect the structure of the magnetic field. Nevertheless, we search for potential signatures of varying grain alignment and dust properties. First, we analyse the product map $S \times p$, looking for residual trends. While $p$ decreases by a factor of 3--4 between $N_H=10^{20}$ cm$^{-2}$ and $N_H=2\times 10^{22}$ cm$^{-2}$, $S \times p$ decreases by only about 25%, a systematic trend observed in both the diffuse ISM and molecular clouds. Second, we find no systematic trend of $S \times p$ with the dust temperature, even though in the diffuse ISM lines of sight with high $p$ and low $S$ tend to have colder dust. We also compare Planck data with starlight polarization in the visible at high latitudes. The agreement in polarization angles is remarkable. Two polarization emission-to-extinction ratios that characterize dust optical properties depend only weakly on $N_H$ and converge towards the values previously determined for translucent lines of sight. We determine an upper limit for the polarization fraction in extinction of 13%, compatible with the $p_\mathrm{max}$ observed in emission. These results provide strong constraints for models of Galactic dust in diffuse gas.

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