Planck intermediate results: XXXIV. The magnetic field structure in the Rosette Nebula

Astronomy Astrophysics A&A 586, A137 (2016) DOI: 10.1051/0004-6361/201525616 c ESO 2016 Planck intermediate results XXXIV. The magnetic field structure in the Rosette Nebula Planck Collaboration: N. Aghanim 55 , M. I. R. Alves 55,87,9, , M. Arnaud 67 , D. Arzoumanian 55 , J. Aumont 55 , C. Baccigalupi 80 , A. J. Banday 87,9 , R. B. Barreiro 60 , N. Bartolo 27,61 , E. Battaner 88,89 , K. Benabed 56,86 , A. Benoit-Levy 21,56,86 , J.-P. Bernard 87,9 , M. Bersanelli 30,45 , P. Bielewicz 87,9,80 , A. Bonaldi 63 , L. Bonavera 60 , J. R. Bond 8 , J. Borrill 12,83 , F. R. Bouchet 56,86 , F. Boulanger 55 , A. Bracco 55 , C. Burigana 44,28,46 , E. Calabrese 85 , J.-F. Cardoso 68,1,56 , A. Catalano 69,66 , A. Chamballu 67,14,55 , H. C. Chiang 24,7 , P. R. Christensen 76,33 , S. Colombi 56,86 , L. P. L. Colombo 20,62 , C. Combet 69 , F. Couchot 65 , B. P. Crill 62,77 , A. Curto 6,60 , F. Cuttaia 44 , L. Danese 80 , R. D. Davies 63 , R. J. Davis 63 , P. de Bernardis 29 , A. de Rosa 44 , G. de Zotti 41,80 , J. Delabrouille 1 , C. Dickinson 63 , J. M. Diego 60 , H. Dole 55,54 , S. Donzelli 45 , O. Dore 62,11 , M. Douspis 55 , A. Ducout 56,52 , X. Dupac 35 , G. Efstathiou 57 , F. Elsner 21,56,86 , T. A. Enslin 72 , H. K. Eriksen 58 , E. Falgarone 66 , K. Ferriere 87,9 , F. Finelli 44,46 , O. Forni 87,9 , M. Frailis 43 , A. A. Fraisse 24 , E. Franceschi 44 , A. Frejsel 76 , S. Galeotta 43 , S. Galli 56 , K. Ganga 1 , T. Ghosh 55 , M. Giard 87,9 , E. Gjerlow 58 , J. Gonzalez-Nuevo 60,80 , K. M. Gorski 62,90 , A. Gregorio 31,43,49 , A. Gruppuso 44 , V. Guillet 55 , F. K. Hansen 58 , D. Hanson 74,62,8 , D. L. Harrison 57,64 , S. Henrot-Versille 65 , D. Herranz 60 , S. R. Hildebrandt 62 , E. Hivon 56,86 , M. Hobson 6 , W. A. Holmes 62 , A. Hornstrup 15 , W. Hovest 72 , K. M. Huffenberger 22 , G. Hurier 55 , A. H. Jaffe 51 , T. R. Jaffe 87,9 , J. Jewell 62 , M. Juvela 23 , R. Keskitalo 12 , T. S. Kisner 71 , J. Knoche 72 , M. Kunz 16,55,2 , H. Kurki-Suonio 23,40 , G. Lagache 5,55 , J.-M. Lamarre 66 , A. Lasenby 6,64 , M. Lattanzi 28 , C. R. Lawrence 62 , R. Leonardi 35 , F. Levrier 66 , M. Liguori 27 , P. B. Lilje 58 , M. Linden-Vornle 15 , M. Lopez-Caniego 60 , P. M. Lubin 25 , J. F. Macias-Perez 69 , B. Maffei 63 , D. Maino 30,45 , N. Mandolesi 44,4,28 , A. Mangilli 56 , M. Maris 43 , P. G. Martin 8 , E. Martinez-Gonzalez 60 , S. Masi 29 , S. Matarrese 27,61,38 , A. Melchiorri 29,47 , L. Mendes 35 , A. Mennella 30,45 , M. Migliaccio 57,64 , M.-A. Miville-Deschenes 55,8 , A. Moneti 56 , L. Montier 87,9 , G. Morgante 44 , D. Mortlock 52 , A. Moss 82 , D. Munshi 81 , J. A. Murphy 75 , P. Naselsky 76,33 , F. Nati 29 , P. Natoli 28,3,44 , C. B. Netterfield 18 , F. Noviello 63 , D. Novikov 79 , I. Novikov 76 , N. Oppermann 8 , L. Pagano 29,47 , F. Pajot 55 , R. Paladini 53 , D. Paoletti 44,46 , F. Pasian 43 , G. Patanchon 1 , O. Perdereau 65 , V. Pettorino 39 , F. Piacentini 29 , M. Piat 1 , D. Pietrobon 62 , S. Plaszczynski 65 , E. Pointecouteau 87,9 , G. Polenta 3,42 , N. Ponthieu 55,50,51 , G. W. Pratt 67 , G. Prezeau 11,62 , S. Prunet 56,86 , J.-L. Puget 55 , R. Rebolo 59,13,34 , M. Reinecke 72 , M. Remazeilles 63,55,1 , C. Renault 69 , A. Renzi 32,48 , I. Ristorcelli 87,9 , G. Rocha 62,11 , C. Rosset 1 , M. Rossetti 30,45 , G. Roudier 1,66,62 , J. A. Rubino-Martin 59,34 , B. Rusholme 53 , M. Sandri 44 , D. Santos 69 , M. Savelainen 23,40 , G. Savini 78 , D. Scott 19 , J. D. Soler 55 , L. D. Spencer 81 , V. Stolyarov 6,64,84 , D. Sutton 57,64 , A.-S. Suur-Uski 23,40 , J.-F. Sygnet 56 , J. A. Tauber 36 , L. Terenzi 37,44 , L. Toffolatti 17,60,44 , M. Tomasi 30,45 , M. Tristram 65 , M. Tucci 16 , J. Tuovinen 10 , L. Valenziano 44 , J. Valiviita 23,40 , B. Van Tent 70 , P. Vielva 60 , F. Villa 44 , L. A. Wade 62 , B. D. Wandelt 56,86,26 , I. K. Wehus 62 , H. Wiesemeyer 73 , D. Yvon 14 , A. Zacchei 43 , and A. Zonca 25 (Affiliations can be found after the references) Received 5 January 2015 / Accepted 8 April 2015 ABSTRACT Planck has mapped the polarized dust emission over the whole sky, making it possible to trace the Galactic magnetic field structure that pervades the interstellar medium (ISM). We combine polarization data from Planck with rotation measure (RM) observations towards a massive star- forming region, the Rosette Nebula in the Monoceros molecular cloud, to study its magnetic field structure and the impact of an expanding H ii region on the morphology of the field. We derive an analytical solution for the magnetic field, assumed to evolve from an initially uniform configuration following the expansion of ionized gas and the formation of a shell of swept-up ISM. From the RM data we estimate a mean value of the line-of-sight component of the magnetic field of about 3 μG (towards the observer) in the Rosette Nebula, for a uniform electron density of about 12 cm −3 . The dust shell that surrounds the Rosette H ii region is clearly observed in the Planck intensity map at 353 GHz, with a polarization signal significantly different from that of the local background when considered as a whole. The Planck observations constrain the plane-of-the-sky orientation of the magnetic field in the Rosette’s parent molecular cloud to be mostly aligned with the large-scale field along the Galactic plane. The Planck data are compared with the analytical model, which predicts the mean polarization properties of a spherical and uniform dust shell for a given orientation of the field. This comparison leads to an upper limit of about 45 ◦ on the angle between the line of sight and the magnetic field in the Rosette complex, for an assumed intrinsic dust polarization fraction of 4%. This field direction can reproduce the RM values detected in the ionized region if the magnetic field strength in the Monoceros molecular cloud is in the range 6.5–9 μG. The present analytical model is able to reproduce the RM distribution across the ionized nebula, as well as the mean dust polarization properties of the swept-up shell, and can be directly applied to other similar objects. Key words. ISM: magnetic fields – polarization – radiation mechanisms: general – radio continuum: ISM – submillimeter: ISM Corresponding author: M. I. R. Alves, e-mail: marta.alves@irap.omp.eu Article published by EDP Sciences A137, page 1 of 16