Multi-wave band Synchrotron Polarization of Gamma-Ray Burst Afterglows
Abstract
Multi-wave band synchrotron linear polarization of gamma-ray burst (GRB) afterglows is studied under the assumption of an anisotropic turbulent magnetic field with a coherence length of the plasma skin-depth scale in the downstream of forward shocks. We find that for typical GRBs, in comparison to optical polarization, the degree of radio polarization shows a similar temporal evolution but a significantly smaller peak value. This results from differences in observed intensity image shapes between the radio and optical bands. We also show that the degree of the polarization spectrum undergoes a gradual variation from the low- to the high-polarization regime above the intensity of the spectral peak frequency, and that the difference in polarization angles in the two regimes is zero or 90°. Thus, simultaneous multi-wave band polarimetric observations of GRB afterglows would be a new determinative test of the plasma-scale magnetic field model. We also discuss theoretical implications from the recent detection of radio linear polarization in GRB 171205A with the Atacama Large Millimeter/submillimeter Array and other models of magnetic field configuration.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 2021
- DOI:
- 10.3847/1538-4357/abf2c2
- arXiv:
- arXiv:2005.03710
- Bibcode:
- 2021ApJ...913...58S
- Keywords:
-
- Astrophysical processes;
- Jets;
- High energy astrophysics;
- Particle astrophysics;
- 104;
- 870;
- 739;
- 96;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 16 pages, 12 figures, revised version of 2, accepted by ApJ in publication