Estimation of 3D structures of cosmic-ray low density region behind shock waves associated with solar flares

摘要

Using the data obtained by GRAPES-3 tracking muon telescope at Ooty, we are going to estimate the 3D structure of low density cosmic ray region caused by large solar flares. Since the GRAPES-3 muon telescope has a large acceptance (3 sr) with fine segmentation (13×13), hourly 2D maps of multi-directional cosmic-ray intensity variations are easily obtained by this telescope. By comparing the time sequence of these 2D maps with the results of computer simulations in which some models of structure of the low density cosmic-ray region behind shock waves are assumed, we will try to extract their 3D structure of the region. In this paper, we examine the time profiles of the Forbush decreases so far observed and compare them with the time profiles of the solar wind velocity. Then, we present a simple 3D shock wave propagation model and draw a sample contour map of cosmic ray intensity for getting the idea about what we will be able to deduce from 2D maps of GRAPES-3 by comparison.