Bibcode
Planck Collaboration; Adam, R.; Ade, P. A. R.; Aghanim, N.; Alves, M. I. R.; Arnaud, M.; Arzoumanian, D.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Bartolo, N.; Battaner, E.; Benabed, K.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bonaldi, A.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bracco, A.; Burigana, C.; Butler, R. C.; Calabrese, E.; Cardoso, J.-F.; Catalano, A.; Chamballu, A.; Chiang, H. C.; Christensen, P. R.; Colombi, S.; Colombo, L. P. L.; Combet, C.; Couchot, F.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Dickinson, C.; Diego, J. M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Ducout, A.; Dupac, X.; Efstathiou, G.; Elsner, F.; Enßlin, T. A.; Eriksen, H. K.; Falgarone, E.; Ferrière, K.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Frejsel, A.; Galeotta, S.; Galli, S.; Ganga, K.; Ghosh, T.; Giard, M.; Gjerløw, E.; González-Nuevo, J.; Górski, K. M.; Gregorio, A.; Gruppuso, A.; Guillet, V.; Hansen, F. K.; Hanson, D.; Harrison, D. L.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hovest, W.; Huffenberger, K. M.; Hurier, G.; Jaffe, A. H.; Jaffe, T. R.; Jones, W. C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R. et al.
Bibliographical reference
Astronomy and Astrophysics, Volume 586, id.A135, 24 pp.
Advertised on:
2
2016
Journal
Citations
153
Refereed citations
142
Description
The role of the magnetic field in the formation of the filamentary
structures observed in the interstellar medium (ISM) is a debated topic
owing to the paucity of relevant observations needed to test existing
models. The Planck all-sky maps of linearly polarized emission from dust
at 353 GHz provide the required combination of imaging and statistics to
study the correlation between the structures of the Galactic magnetic
field and of interstellar matter over the whole sky, both in the diffuse
ISM and in molecular clouds. The data reveal that structures, or ridges,
in the intensity map have counterparts in the Stokes Q and/or U maps. We
focus our study on structures at intermediate and high Galactic
latitudes, which cover two orders of magnitude in column density, from
1020 to 1022 cm-2. We measure the
magnetic field orientation on the plane ofthe sky from the polarization
data, and present an algorithm to estimate the orientation of the ridges
from the dust intensity map. We use analytical models to account for
projection effects. Comparing polarization angles on and off the
structures, we estimate the mean ratio between the strengths of the
turbulent and mean components of the magnetic field to be between 0.6
and 1.0, with a preferred value of 0.8. We find that the ridges are
usually aligned with the magnetic field measured on the structures. This
statistical trend becomes more striking for increasing polarization
fraction and decreasing column density. There is no alignment for the
highest column density ridges. We interpret the increase in alignment
with polarization fraction as a consequence of projection effects. We
present maps to show that the decrease in alignment for high column
density is not due to a loss of correlation between the distribution of
matter and the geometry of the magnetic field. In molecular complexes,
we also observe structures perpendicular to the magnetic field, which,
statistically, cannot be accounted for by projection effects. This first
statistical study of the relative orientation between the matter
structures and the magnetic field in the ISM points out that, at the
angular scales probed by Planck, the field geometry projected on the
plane of the sky is correlated with the distribution of matter. In the
diffuse ISM, the structures of matter are usually aligned with the
magnetic field, while perpendicular structures appear in molecular
clouds. We discuss our results in the context of models and MHD
simulations, which attempt to describe the respective roles of
turbulence, magnetic field, and self-gravity in the formation of
structures in the magnetized ISM.