WSRT Faraday tomography of the Galactic ISM at $\mathsf{\lambda \sim 0.86}$ m

• Published in: Astronomy and astrophysics (Berlin) Vol. 471; no. 2; pp. L21 - L24
• Main Authors: Schnitzeler, D. H. F. M., Katgert, P., de Bruyn, A. G.
• Format: Journal Article
• Language: English
• Published: EDP Sciences 01.08.2007
• Subjects: ISM: magnetic fields; ISM: structure; magnetic fields; radio continuum: ISM; techniques: miscellaneous; techniques: polarimetric
• ISSN: 0004-6361; 1432-0746
• DOI: 10.1051/0004-6361:20077635

Aims.We investigate the distribution and properties of Faraday rotating and synchrotron emitting regions in the Galactic ISM in the direction of the Galactic anti-centre. Methods.We apply Faraday tomography to a radio polarization dataset that we obtained with the WSRT. We developed a new method to calculate a linear fit to periodic data, which we use to determine rotation measures from our polarization angle data. From simulations of a Faraday screen + noise we could determine how compatible the data are with Faraday screens. Results.An unexpectedly large fraction of 14% of the lines-of-sight in our dataset show an unresolved main component in the Faraday depth spectrum. For lines-of-sight with a single unresolved component we demonstrate that a Faraday screen in front of a synchrotron emitting region that contains a turbulent magnetic field component can explain the data.