Faraday rotation of Cygnus A - magnetic fields in cluster gas

Journal Article · Fri May 01 04:00:00 EDT 1987 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/165229· OSTI ID:6270237

Dreher, J W; Carilli, C L; Perley, R A

Multifrequency, multiconfiguration observations with the VLA have allowed, for the first time, detailed mapping of the rotation measure (RM) of the prominent extragalactic radio source Cygnus A. It is found that this source lies behind a deep Faraday screen, with the rotation measure varying from -4000 to +3000 rad/sq m for the eastern lobe, and from -2000 to +1500 rad/sq m for the western lobe. Gradients in both lobes commonly exceed 300 rad/sq m/arcsec. The overall pattern in RM is the same in each lobe, increasing from east to west, leading to the conclusion that the magnetic field is ordered on scales of about 20 to 30 kpc. There is no evidence for internal depolarization. The authors examine, and reject, the hypothesis that this Faraday screen has a Galactic origin and propose that its origin is in the intracluster gas in which Cygnus A is embedded. 66 references.

• Research Organization: MIT, Cambridge, MA; National Radio Astronomy Observatory, Socorro, NM
• OSTI ID: 6270237
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 316; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COSMIC GASES
COSMIC RADIO SOURCES
ELECTROMAGNETIC RADIATION
FARADAY EFFECT
FLUIDS
GALAXY CLUSTERS
GASES
INTERSTELLAR MAGNETIC FIELDS
MAGNETIC FIELDS
POLARIZATION
RADIATIONS
RADIOWAVE RADIATION