Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10700961 | Chinese Astronomy and Astrophysics | 2005 | 7 Pages |
Abstract
The characteristics of the self absorption of gyrosynchrotron emission are investigated in detail and its optical depth is estimated for a model of radio microwave source in a magnetic dipole field. It is shown that: (1) the self absorptivity kvâ decreases rapidly with increasing harmonic number s(= v/vB), so that only the absorption at lower harmonics (s ⤠5) can affect substantially the microwave burst spectrum; (2) this decrease becomes faster with increasing energy spectral index δ and decreasing low-energy cutoff E0 of energetic electrons; (3) kvâ increases also obviously with increasing view angle Ï and reaches maximum around 70°-75°; (4) the optical depth of the self absorption Ïselfvâ for 2 ⤠s ⤠5 varies in the range 101 - 10â2, assuming a number density of energetic electrons of N=103cmâ3. This value is 103 - 104 lower than that of the gyroresonance absorption. Ïselfvâ would be overestimated in the uniform magnetic field case. Only when N is larger than 104cmâ3 does the optical depth of the self absorption become comparable to that of the gyroresonance absorption.
Keywords
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Astronomy and Astrophysics
Authors
Zhou Ai-hua,