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Title: Synchrotron polarization in blazars

We present a detailed analysis of time- and energy-dependent synchrotron polarization signatures in a shock-in-jet model for γ-ray blazars. Our calculations employ a full three-dimensional radiation transfer code, assuming a helical magnetic field throughout the jet. The code considers synchrotron emission from an ordered magnetic field, and takes into account all light-travel-time and other relevant geometric effects, while the relevant synchrotron self-Compton and external Compton effects are handled with the two-dimensional Monte-Carlo/Fokker-Planck (MCFP) code. We consider several possible mechanisms through which a relativistic shock propagating through the jet may affect the jet plasma to produce a synchrotron and high-energy flare. Most plausibly, the shock is expected to lead to a compression of the magnetic field, increasing the toroidal field component and thereby changing the direction of the magnetic field in the region affected by the shock. We find that such a scenario leads to correlated synchrotron + synchrotron-self-Compton flaring, associated with substantial variability in the synchrotron polarization percentage and position angle. Most importantly, this scenario naturally explains large polarization angle rotations by ≳ 180°, as observed in connection with γ-ray flares in several blazars, without the need for bent or helical jet trajectories or other nonaxisymmetric jet features.
Authors:
;  [1] ;  [2]
  1. Astrophysical Institute, Department of Physics and Astronomy, Ohio University, Athens, OH 45701 (United States)
  2. Institute of Physics and Astronomy, University of Potsdam, D-14476 Potsdam-Golm (Germany)
Publication Date:
OSTI Identifier:
22356476
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 789; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPUTERIZED SIMULATION; EMISSION; ENERGY DEPENDENCE; FOKKER-PLANCK EQUATION; GALAXIES; GAMMA RADIATION; JET MODEL; MAGNETIC FIELDS; MONTE CARLO METHOD; PLASMA; POLARIZATION; RELATIVISTIC RANGE; ROTATION; STARS; SYNCHROTRON RADIATION; THREE-DIMENSIONAL CALCULATIONS; TRAJECTORIES; TWO-DIMENSIONAL CALCULATIONS; VISIBLE RADIATION