Astronomy and Astrophysics, volume 398, 993-1005 (2003/2-2)
The effect of HII regions on rotation measure of pulsars.
MITRA D., WIELEBINSKI R., KRAMER M. and JESSNER A.
Abstract (from CDS):
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 l∼149° (Region 1) and four pulsars towards l∼113° (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 5.7µG. For the large-scale component of the Galactic magnetic field we determine a field strength of 1.7±1.0µG. This average field is constant on Galactic scales lying within the Galactic longitude range of 85°<l<240° and we find no evidence for large scale field reversal upto 5-6kpc. We highlight the great importance to include the effects of foreground emission in any systematic study.
Galaxy: structure - magnetic fields - ISM: HII regions - stars: pulsars: general