Joint 3D modelling of the polarized Galactic synchrotron and thermal dust foreground diffuse emission

¹ LPSC, Université Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut National Polytechnique de Grenoble, 53 avenue des Martyrs, 38026 Grenoble Cedex, France
e-mail: macias@lpsc.in2p3.fr
² Institut d’AstrophysiqueSpatiale, Centre Universitaire d’Orsay, Bat. 121, 91405 Orsay Cedex, France
³ Centre d’Etude Spatiale des Rayonnements, 9 avenue du Colonel Roche, 31028 Toulouse, France
⁴ Laboratoire d’astrophysique de Grenoble, OSUG, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 9, France
⁵ Institut Neel, 25 rue des Martyrs, BP 166, 38042 Grenoble Cedex 9, France
⁶ Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
⁷ Max-Planck Institute for Astrophysics, Karl Schwarzschild Str. 1, 85741 Garching, Germany
⁸ Laboratoire de l’Accélérateur Linéaire, BP 34, 91898 Orsay Cedex, France

Received: 23 March 2010
Accepted: 19 October 2010

Abstract

Aims. We present for the first time a coherent model of the polarized Galactic synchrotron and thermal dust emissions that are likely to form the predominant diffuse foregrounds for measuring the polarized CMB fluctuations by the Planck satellite mission.

Methods. We produced 3D models of the Galactic magnetic field including regular and turbulent components, and of the distribution of matter in the Galaxy including relativistic electron and dust grain components. By integrating along the line of sight, we constructed maps of the polarized Galactic synchrotron and thermal dust emission for each of these models and compared them to currently available data. We consider the 408 MHz all-sky continuum survey, the 23 GHz band of the Wilkinson Microwave Anisotropy Probe, and the 353 GHz Archeops data.

Results. The best-fit parameters obtained are consistent with previous estimates in the literature based only on synchrotron emission and pulsar rotation measurements and this allows us to reproduce the large-scale features observed in the data. Unmodeled local Galactic structures and the effect of turbulence make it difficult to accurately reconstruct observations in the Galactic plane.

Conclusions. Finally, using the best-fit model we are able to estimate the expected polarized foreground contamination at the Planck frequency bands. For the CMB bands, 70, 100, 143 and 217 GHz, at high Galactic latitudes although the CMB signal dominates in general, a significant foreground contribution is expected at large angular scales. In particular, this contribution will dominate the CMB signal for the B modes expected from realistic models of a background of primordial gravitational waves.