Mode of variation of the scattering index parameter in the interstellar medium.
Abstract
Using recent data obtained for decorrelation frequency f_{ν} for 20 pulsars with dispersion measure DM ≤ 50 pc cm^{3}, we investigate whether there is any systematic variation of the scattering index parameter, (<∆N^{2}_{e}>/L)^{1/2} = ∊, in the interstellar medium (ISM). It is found that ∊ appears to vary uniformly in certain regions of the ISM, defined approximately by 110 ≤ Z < 420 pc and with corresponding Galactic coordinates given by 26° < b < 87°. Elsewhere, ∊ is found to have a very random variation. The results for ∊ arising from values of f_{ν} obtained earlier by other authors are compared with our result. It is observed that more data are required before a definite conclusion on the mode of variation of ∊ can be made.
 Publication:

The Astronomical Journal
 Pub Date:
 July 1981
 DOI:
 10.1086/112989
 Bibcode:
 1981AJ.....86.1110O
 Keywords:

 Electromagnetic Scattering;
 Interstellar Matter;
 Pulsars;
 Scattering Coefficients;
 Astronomical Coordinates;
 Electron Density (Concentration);
 Positrons;
 Scintillation;
 Astrophysics