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Rotation measures in AGN jets seen by VLA at 21 cm to 6 mm

Published online by Cambridge University Press:  24 March 2015

Evgeniya V. Kravchenko
Affiliation:
Lebedev Physical Institute, Profsoyuznaya 84/32, 117997 Moscow, Russia email: [email protected]
William D. Cotton
Affiliation:
National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475, USA
Yuri Y. Kovalev
Affiliation:
Lebedev Physical Institute, Profsoyuznaya 84/32, 117997 Moscow, Russia email: [email protected]
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Abstract

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We present Faraday rotation measure (RM) properties of seven active galactic nuclei (AGN), observed with the NRAO VLA at three epochs in 2012-2014. Data was taken at 1.4, 2.2, 5.0, 8.2, 15.4, 22.4, 33.5 and 43.1 GHz quasi simultaneously in full polarization mode. For the first time RMs were calculated in a range of wavelengths covering more than one order of magnitude: from 21 cm up to 6 mm. We measured RM for each source and showed a tendency to increase its value toward high frequencies according to the law |RM|~νa with a = 1.6±0.1. For 0710+439, we observed an increase over the frequency range of 4 orders of magnitude and measured one of the highest RM ever, (−89±1)⋅103 rad/m2. Analysis of different epochs shows variations of the value and the sign of RM on short and long time-scales. This may be caused by changing physical conditions in the compact regions of the AGN jets, e.g., strength of magnetic field, particle density and so on.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2015 

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