1. Rotation of Polarization Angle in Gamma-Ray Burst Prompt Phase. II. The Influence of the Parameters.
- Author
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Li, Jia-Sheng, Wang, Hao-Bing, and Lan, Mi-Xiang
- Subjects
MAGNETIC reconnection ,BREWSTER'S angle ,LIGHT curves ,MAGNETIC fields ,ACTINIC flux ,GAMMA ray bursts - Abstract
In addition to the light curve and energy spectrum, polarization is also important for inferring the physical properties of the gamma-ray burst (GRB). Rotation of the polarization angle (PA) with time will cause depolarization of the time-integrated polarization degree. However, it has rarely been studied before. Here, we use a magnetic reconnection model with a large-scale ordered aligned magnetic field in the emitting region to study the influence of the parameters on the PA rotations in the GRB prompt phase. We find that the half-opening angle of the jet θ
j , the observational angle θV , and the bulk Lorentz factor Γ all have significant impacts on the PA rotations. The PA rotations are affected by the product value of θj Γ0 (Γ0 is the normalization factor of Γ with Γ (r) = Γ 0 (r / r 0) s ), but are roughly independent of the concrete values of both θj and Γ0 . For the typical parameters, the changes of the PA within T90 (△PA) would be within (12°, 66°) for slight off-axis observations, where T90 is the duration of the burst with the accumulated flux density ranging from 5% to 95%. The q range for △PA > 10° becomes smaller with the increase of the product value of θj Γ0 . The most significant PA rotation with △PA ∼ 90° will happen when θj Γ0 > 50 and 1.0 < q ≤ 1.2. [ABSTRACT FROM AUTHOR]- Published
- 2024
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