Revealing compact structures of interstellar plasma in the Galaxy with RadioAstron

Abstract

The aim of our work was to study the spatialstructure of inhomogeneities in the 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 the RadioAstron space-ground radio interferometer at 324 MHz. We measured the angular size of the scattering discs and found it to be in the range 0.63-2.1 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. Based on the results, we came to the conclusion that scattering is produced mainly by compact plasma layers and the uniform model of inhomogeneity distribution along the line of sight is not applicable.