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| Main Authors: | , , |
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| Format: | Preprint |
| Published: |
2023
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2306.16618 |
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Table of Contents:
- 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 is rarely 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 GRB prompt phase. We find that half-opening angle of the jet $θ_{j}$, the observational angle $θ_{V}$, and the bulk Lorentz factor $Γ$ all have significant impacts on the PA rotations. The PA rotations are affected by the product value of $θ_{j}Γ_{0}$ ($Γ_{0}$ 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 $θ_{j}$ and $Γ_{0}$. For the typical parameters, the changes of the PA within $T_{90}$ ($\triangle$PA) would be within ($12^\circ$, $66^\circ$) for slight off-axis observations, where $T_{90}$ is the duration of the burst with the accumulated flux density ranging from $5\%$ to $95\%$. The $q$ range for $\triangle$PA$>10^{\circ}$ becomes smaller with the increase of the product value of $θ_{j}Γ_{0}$. The most significant PA rotation with $\triangle$PA$\sim90^{\circ}$ will happen when $θ_{j}Γ_{0}>50$ and $1.0<q\leq1.2$.