Faraday rotation measure irregularities through the supernova remnant CTA 1 - A site of enhanced interstellar plasma turbulence

Abstract

view Abstract Citations (14) References (20) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Faraday Rotation Measure Irregularities through the Supernova Remnant CTA 1: A Site of Enhanced Interstellar Plasma Turbulence Simonetti, John M. Abstract We probed Faraday rotation measure (RM) irregularities within and near the remnant CTA 1. The purpose was to use a relatively new approach to test the hypothesis that supernovae generate the plasma turbulence that scatters radio waves. We made VLA observations of four extragalactic radio sources seen through CTA 1, and of five extragalactic sources on lines of sight outside but near the remnant. The two sets of sources are intrinsically similar. Outside CTA 1 the RM structure function (intra and intersource [{DELTA}RM]^2^ vs. angular separation) is consistent with the result for general lines of sight at high galactic latitude. It also agrees with a simple model where we assume that only electron-density irregularities determine RM irregularities (the magnetic field is assumed uniform), and we assume the electron density irregularities at parsec scales are described by an extrapolation of the (Kolmogorov) power spectrum for the fine-scale (< 10^13^ cm) electron-density irregularities that scatter radio waves from high-latitude sources. In comparison, small angular-scale RM irregularities are stronger through CTA 1: this remnant is a site of enhanced plasma turbulence. Applying the simple model to within CTA 1 suggests the scattering measure SM of the remnant (the line- of-sight integral within the remnant of C^2^_n_, the intensity of the spectrum of electron-density irregularities) is 0.2-5 x 10^-3^m^-20/3^ kpc. This SM is of the same order of magnitude as for the entire line-of- sight path length outside CTA 1 through the large scale-height diffuse component of the scattering medium. The suggested average C^2^_n_ within the remnant is at least an order of magnitude larger than outside the remnant. Therefore, collectively supernovae may be at least partly responsible for the wide-spread, large scale-height turbulence. However, if individual supernova remnants are responsible for the clumps of strong turbulence within the galactic plane their scattering measures must be 10^3^-10^4^ larger than we suggest for CTA I. Publication: The Astrophysical Journal Pub Date: February 1992 DOI: 10.1086/171002 Bibcode: 1992ApJ...386..170S Keywords: Cosmic Plasma; Faraday Effect; Magnetohydrodynamic Turbulence; Supernova Remnants; Computational Astrophysics; Interstellar Magnetic Fields; Linear Polarization; Very Large Array (Vla); Astrophysics; ISM: INDIVIDUAL ALPHANUMERIC: CTA 1; ISM: MAGNETIC FIELDS; ISM: SUPERNOVA REMNANTS; TURBULENCE full text sources ADS | data products SIMBAD (19) NED (16)