The galactic latitude distribution of the intensity modulation index of radio sources in the wide frequency range

Abstract

A statistical analysis of t,he modulation index (m) distribution along the galactic latitude for different samples of variable extragalactic radio sources has been performed in a wide freqiiency range from 80 MHz to 37 GHz. The distributions of the median m values have dernonstrat.st-l a striking monotony at all frequencies from meters to rnillirnetres in spite of a considerable scattering in the individual m values. known for low frequency variability and flickering. It was explained by refraction iiitetatellal scintillation (RISS). The same distribution of In is unexpected for cenhietre and niilliiiietre wavelengths. The galactic latitude distribution of rn obtained are compared with a simple HISS thwwy It is shown that the difference between the observed data and the simple theory of KISS is sig1iifir;mt at low galactic latitudes Ibl 5 15' f 30' almost for all frequencies considered. Some specirktrons about the galactic latitude distribution discovered are given in the frame of interstellar s&i:iUa- tion. One of them is the flattening of the electron density fluctuation spectrum at low sa!actir latitudes. Some correlation of ni with the galactic latitude