Revisiting the structure function of PSR B0950+08 scintillations

Abstract

ABSTRACT The observational structure function of the scintillations of the radio pulsar PSR B0950+08 was fitted, a decade ago, with a power law with index 1 ± 0.05. This was interpreted as an appreciable deviation from the commonly observed index of 5/3, expected for Kolmogorov turbulence. In this paper, it is suggested that the observations are consistent with a Kolmogorov turbulence and that the apparent deviation is due to a turbulent region with an effective depth, which is comparable to the observed lateral scales on the plane of the sky, spanned by the pulsar beam. Alternatively, the fitted index of 1 is consistent with an underlying compressive turbulence and an even smaller depth. In the first interpretation, the depth is (5.5 ± 1.8) × 108 cm. In the second one, the depth is ≲4 × 107 cm. These estimates lend support for the existence of extremely thin, ionized scattering screens in the local interstellar cloud that have been proposed a decade ago.