Polarization of Compact Radio Sources

Abstract

view Abstract Citations (7) References (40) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Polarization of Compact Radio Sources Bjoernsson, C. -I. Abstract If the flat spectra of compact radio sources are due to an inhomogeneous source structure, neither synchrotron self-absorption nor a tangled magnetic field is the likely cause for the low polarization of the integrated flux. Instead, the low integrated polarization, as well as the polarization properties of the spatially resolved jet, is ascribed to internal Faraday rotation and a coherent magnetic field, which has its main component along the jet axis. The preferred values of both the degree of polarization and the polarization angle, as well as their frequency independence, can be understood within standard synchrotron models, if the Faraday rotating electrons are just the nonrelativistic end of the power-law distribution of relativistic electrons, which is responsible for the observed synchrotron radiation. Hence, contrary to previous claims, the polarization properties do not exclude an efficient Fermi-type acceleration mechanism as the origin for the relativistic electrons. However, it is shown that the polarization characteristics of Faraday-thick shocks in a jet make them unlikely as acceleration sites. The VLBI core is not just the unresolved continuation of the inner jet, but contains a component which is directly related to, and probably spatially coincides with, the blazar emission region. The implied features of this component include both a large-scale magnetic field and large Doppler factors; in fact, the inferred Doppler factors are so large that relativistic streaming is indicated. It is argued that many of the observed properties of compact radio sources, which are difficult to account for within standard synchrotron models, can be attributed to this blazar component. Publication: The Astrophysical Journal Pub Date: October 1993 DOI: 10.1086/173217 Bibcode: 1993ApJ...416..104B Keywords: GALAXIES: JETS; POLARIZATION; RADIATION MECHANISMS: MISCELLANEOUS; RADIO CONTINUUM: GALAXIES full text sources ADS |