Linear and Circular Polarization Properties of Jets

Abstract

I discuss the transfer of polarized synchrotron radiation in relativistic jets. I argue that the main mechanism responsible for the circular polarization properties of compact synchrotron sources is likely to be Faraday conversion and that, contrary to common expectation, a significant rate of Faraday rotation does not necessarily imply strong depolarization. The long-term persistence of the sign of circular polarization, observed in some sources, is most likely due to a small net magnetic flux generated in the central engine, carried along the jet axis and superimposed on a highly turbulent magnetic field. I show that the mean levels of circular and linear polarizations depend on the number of field reversals along the line of sight and that the gradient in Faraday rotation across turbulent regions can lead to "correlation depolarization''. The model is potentially applicable to a wide range of synchrotron sources. In particular, I demonstrate how the model can naturally explain the excess of circular over linear polarization in the Galactic Center (Sgr A*) and the low-luminosity AGN M81*.

Invited Talk, to appear in "Circular Polarisation in Relativistic Jet Sources", Astrophysics and Space Science, Fender R.P. and Macquart J.-P. (Eds)

References in corpus (15)

• The Supermassive Black Hole at the Galactic Center
• On Pair Content and Variability of Sub-Parsec Jets in Quasars
• Constraining the Accretion Rate Onto Sagittarius A* Using Linear Polarization
• Sgr A* Polarization: No ADAF, Low Accretion Rate, and Non-Thermal Synchrotron Emission
• The Spectrum and Variability of Circular Polarization in Sagittarius A* from 1.4 to 15 GHz
• Circular Polarization of Radio Emission from Relativistic Jets
• Detection and Measurement of Parsec-Scale Circular Polarization in Four AGN
• Detection of Circular Polarization in the Galactic Center Black Hole Candidate Sagittarius A*
• Circular polarization from stochastic synchrotron sources
• Parsec-Scale Circular Polarization Observations of 40 Blazars
• Scintillation-Induced Circular Polarization in Pulsars and Quasars
• Confirmation and Analysis of Circular Polarization from Sagittarius A*
• Variable circular polarisation associated with relativistic ejections from GRS 1915+105
• Discovery of circularly polarised radio emission from SS 433
• Detection of Circular Polarization in M81*

Cited by in corpus (1)

• Polarization and structure of relativistic parsec-scale AGN jets