The effect of HII regions on rotation measure of pulsars
Max-Planck Institute für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
2 University of Manchester, Jodrell Bank Observatory, Macclesfield SK11 9DL, UK
Corresponding author: D. Mitra, email@example.com
Accepted: 12 November 2002
We have obtained new rotation measures for 11 pulsars observed with the Effelsberg 100-m radio telescope, in the direction of the Perseus arm. Using a combination of 34 published and the 11 newly measured pulsar rotation measures we study the magnetic field structure towards the Perseus arm. We find that two pulsars towards (Region 1) and four pulsars towards (Region 2) lie behind HII regions which seriously affect the pulsar rotation measures. The rotation measure of PSR J2337+6151 seems to be affected by its passage through the supernova remnant G114.3+0.3. For Region 1, we are able to constrain the random component of the magnetic field to G. For the large-scale component of the Galactic magnetic field we determine a field strength of G. This average field is constant on Galactic scales lying within the Galactic longitude range of and we find no evidence for large scale field reversal upto 5–6 kpc. We highlight the great importance to include the effects of foreground emission in any systematic study.
Key words: Galaxy: structure / magnetic fields / ISM: HII regions / stars: pulsars: general
© ESO, 2003