Faraday rotation and physical conditions in the Crab Nebula

Journal Article · Fri Feb 01 04:00:00 EST 1991 · Astrophysical Journal; (USA)

DOI:https://doi.org/10.1086/169686· OSTI ID:5914300

Bietenholz, M F; Kronberg, P P ^[1]

---

1. Toronto Univ. (Canada)

New, high-resolution radio images of the Crab Nebula at four frequencies are presented. These are used to construct reliable depolarization and rotation measure (RM) maps. The polarization maps show considerable small-scale structure. The features in the RM map appear unrelated to any structure visible in the total intensity. The large-scale RM is remarkably constant at about -21 rad/sq m across the nebula, and is mostly external, with at most a small contribution from the nebula itself. The synchrotron-emitting regions are quite separate from those in which most of the Faraday rotation occurs. In the former, the scale size of the magnetic field structure is about 0.1 pc and the (thermal) densities are low. It is shown that the radio depolarization must be caused by a network of Faraday rotating filaments containing thermal material. Most of these filaments are too small to be seen individually, have a filling factor of about 0.3, and RMs of a few hundred radians per square meter. 28 refs.

• OSTI ID: 5914300
• Journal Information: Astrophysical Journal; (USA), Journal Name: Astrophysical Journal; (USA) Vol. 368; ISSN ASJOA; ISSN 0004-637X
• 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
BREMSSTRAHLUNG
COSMIC RADIO SOURCES
CRAB NEBULA
ELECTROMAGNETIC RADIATION
FARADAY EFFECT
IMAGES
MAGNETIC FIELDS
MORPHOLOGY
NEBULAE
POLARIZATION
PULSARS
RADIATIONS
RADIOWAVE RADIATION
STELLAR ACTIVITY
STELLAR RADIATION
STELLAR WINDS
SUPERNOVA REMNANTS
SYNCHROTRON RADIATION