Synchrotron polarization in blazars

Journal Article · Tue Jul 01 00:00:00 EDT 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/789/1/66· OSTI ID:22356476

Zhang, Haocheng; Böttcher, Markus ^[1]; Chen, Xuhui ^[2]

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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)

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.

• OSTI ID: 22356476
• Journal Information: Astrophysical Journal, Vol. 789, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

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