Ion acoustic solitary waves in plasma with nonthermal electron and positron

In this Letter, the characteristics of ion acoustic solitary waves are studied in plasmas containing ion fluid, nonthermally distributed electron and positron. The possibility of solitons formation and the effect of nonthermally distributed electrons on solitons are studied by pseudo-potential method. We show that the presence of nonthermal electrons modifies the parametric region where ion acoustic solitons can exist. The relevancy of this investigation to observations in the magnetosphere of density depressions is briefly pointed out. We also obtain linear dispersion relation by using the standard normal-modes analysis.