Abstract
We have conducted a survey of Faraday rotation in a sample of 191
compact radio-loud AGNs as part of the MOJAVE (Monitoring of Jets in
Active galactic nuclei with VLBA Experiments) project. The observations
were carried out with the VLBA at 8.1, 8.4, 12.1 and 15.3 GHz over 12
epochs in 2006. We detect sufficiently strong linear polarization in 159
out of 211 observations to calculate the rotation measure values,
resulting in a large enough sample for statistical analysis of the
Faraday rotation in blazars. These Faraday rotation measures can be used
to study the intrinsic magnetic field order and orientation in
parsec-scale blazar jets. Our sample includes 119 sources listed in the
1FGL or 2FGL catalogs and we detect rotation measure values in 111 out
of 131 maps. Of the 72 sources that are not in the gamma-ray catalogs we
detect RM in 48 out of 80 maps. The median RM values of the LAT-detected
sources do not differ significantly from the non-LAT-detected sources.
Nine of the sources in our sample have resolved enough jets to study the
transverse Faraday rotation structure, and we detect significant
transverse rotation measure gradients in four sources. In two of these
(3C~273 and 3C~454.3) there is additional evidence to support helical
magnetic field in the parsec-scale jets. The two others (0923+392 and
2230+114) require further observations to identify the nature of the
gradient. It is interesting that three of the four sources with
significant rotation measure gradients are sources that have shown large
gamma-ray flares.
Original language | English |
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Title of host publication | Fermi & Jansky Proceedings - eConf |
Number of pages | 5 |
Volume | C1111101 |
Publication status | Published - 2012 |
MoE publication type | A4 Conference publication |
Keywords
- Astrophysics - High Energy Astrophysical Phenomena