Open AccessUnusual radio properties of the BL Lac object 0820+225
Author(s) -
Gabuzda D.C.,
Pushkarev A.B.,
Garnich N.N.
Publication year - 2001
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2001.04446.x
Subject(s) - physics , bl lac object , very long baseline interferometry , astrophysics , polarization (electrochemistry) , rotation (mathematics) , redshift , superluminal motion , astronomy , blazar , galaxy , geometry , gamma ray , chemistry , mathematics
We present the results of simultaneous VLBA polarization observations of the BL Lacertae object 0820+225 at 5, 8 and 15 GHz, together with earlier images at 5 GHz. This source has an unusually rich total intensity and polarization structure compared with other objects with comparable redshifts. The magnetic field in the inner part of the complex and highly twisted VLBI jet is transverse, as is typical of BL Lacertae objects, but becomes roughly longitudinal further from the core, possibly as a result of shear. Although the integrated rotation measure of 0820+225 is modest, the rotation‐measure distribution on parsec scales is non‐uniform, and clearly shows regions where the rotation measure is substantially higher than the integrated value.