Some glimpses of the plasma processes involved in power spectra of radio pulsars

Abstract

Although more than a half-century since pulsar discovery, the field of pulsar astronomy has attained an unprecedented level of success and has opened several windows in astronomy, very few theories have been put forwarded to investigate the nature of power spectra and emission properties of radio pulsars. There has been a copious amount of observation dedicated to investigating the nature and shape of radio pulsar’s power spectra. In this paper, I have suggested some alternative plasma processes in the frame of general parametric instability, such as Stimulated Raman Scattering (SRS) and Stimulated Compton Scattering (SCS) as a potential probe to generate power spectra theoretically. There are basically three prominent processes in which electromagnetic waves can undergo scattering in an ambient plasma medium. First, one is very well-known Compton scattering; it is when the scattering of radiation occurs by a single electron. The second and third ones are SRS and SCS, which are the relatively less known plasma phenomena. By definition, SRS is a process where the scattering of radiation occurs by longitudinal electron plasma mode, whereas SCS occurs by highly damped electron plasma mode. I have explored the possibility of explaining the radio power spectra of pulsar under different circumstances of plasma. I have computed the growth rates of SRS and SCS instabilities numerically. Thereafter, I have produced full radio power spectra of the pulsars PSRB 2111+46, PSRB 0329+54 theoretically by assuming typical pulsar parameters, dispersion relation associated with the plasma of three-wave interacting parametric instability process and the spatial variation associated with different plasma parameters like plasma density, Lorentz factor of electrons, frequency, and input flux of the pump wave.