Investigation of pulsar diffractive scintillation at 4.75 and 10.55 GHz

Abstract

Investigations of the intensity fluctuations of 17 pulsars at 4.75 and 10.55 GHz reveal two well-defined separable components. One is obviously caused by interstellar scintillation on a temporal scale of a few minutes and longer, which made it possible to extract unambiguously scintillation indices, correlation times and their dependence on frequency and distance; the other is with high certainty related to intrinsic pulse flux variations. Analysis of the correlation function, the temporal structure function and the power spectrum of pulsar scintillation in the weak regime and comparison with theoretical predictions based on the "Kolmogorov" and "broken power law" model indicate that the three-dimensional spectrum of the electron density fluctuations may be approximated by a power law with an index n ≥ 4 on a spatial scale of 109 - 1011 cm. It is shown, furthermore, by analysis of the functional dependence of the critical frequency on distance, that turbulence in the interstellar medium must be nearly statistically homogeneous at distances R ≤ 1 kpc but inhomogeneous on larger scales.