Microwave emission from the trapped and precipitated electrons in solar bursts

¹ INPE - Instituto Nacional de Pesquisas Espaciais, Brazil e-mail: jercosta@craam.mackenzie.br
² IPM/CRAAM - Instituto Presbiteriano Mackenzie/Centro de Rádio Astronomia e Astrofísica Mackenzie, Brazil

Received: 28 October 2004
Accepted: 7 February 2005

Abstract

We analyzed the microwave spectra of a sample of 13 solar flares out of 40 events observed by the Nobeyama Radio Polarimeter in the period of August 8, 1998 through November 24, 2001. The solar burst time profiles were filtered to separate the slow component from the fast structures which were associated with the emission from trapped particles and to the emission from the minor precipitating population, respectively. The spectra of both components suggest a trap in a region with a mean magnetic field of about 600 G and a minor emission from the loop legs with a magnetic field of 1100 G, resulting in a mirror ratio of about two. The spectral indices of the optically thin emission from these two regions indicate pitch angle diffusion by Coulomb collisions.