Revealing compact structures of interstellar plasma in the Galaxy with RadioAstron

TL;DR

This study used RadioAstron to analyze the spatial structure of interstellar plasma in five pulsar directions, revealing that scattering is mainly caused by compact plasma layers rather than a uniform distribution.

Contribution

It provides new measurements of scattering disk sizes and identifies the presence of compact plasma layers as the primary cause of scattering in the interstellar medium.

Findings

Measured scattering disk sizes between 0.63 and 3.2 mas.

Determined the positions of scattering screens along the line of sight.

Concluded that scattering is mainly due to compact plasma layers, not uniform inhomogeneities.

Abstract

The aim of our work was to study the spatial structure of inhomogeneities of interstellar plasma in the directions of five pulsars: B0823+26, B0834+06, B1237+25, B1929+10, and B2016+28. Observations of these pulsars were made with RadioAstron space-ground radio interferometer at 324 MHz. We measured the angular size of the scattering disks to be in range between 0.63 and 3.2 mas. We determined the position of scattering screens on the line of sight. Independent estimates of the distances to the screens were made from the curvature of parabolic arcs revealed in the secondary spectra of four pulsars. The model of uniform distribution of inhomogeneities on the line of sight is not suitable. According to the results, we came to the conclusion that scattering is mainly produced by compact plasma layers and the uniform model of inhomogeneties distribution on the line of sight in not applicable.