On the origin of giant pulses in radio pulsars

Abstract

Abstract. Induced Compton scattering of radio emission off the particles of the ultrarelativistic highly magnetized plasma of pulsar magnetosphere is considered. The scattering between the photon beams of substantially differing frequencies and orientations appears to result in photon transfer to the higher frequency. With the decreasing spectrum of pulsar radio emission, this may imply a significant amplification of the higher-frequency intensity. A detailed analysis shows that the rays of widely spaced frequencies can have different orientations, at least at certain locations in the pulsar magnetosphere. The numerical estimates confirm the possibility of an efficient beam-to-beam scattering in the pulsars known as giant pulse sources. Thus, the intensity amplification on account of induced scattering of the lower-frequency radiation is suggested to underlie the giant pulse phenomenon. A huge pulse-to-pulse scatter in the observed intensities of the giant pulse sources (over more than three orders of magnitude) testifies to significant variations of the efficiency of amplification. If this variability is attributed to the fluctuations of both the particle number density and the incident intensity and the latter are considered as the partially correlated Gaussian random quantities, one arrives at the power-law distribution of strong pulses in intensity. The formation of the giant pulse substructure, the broad-band spectral behaviour of the scattering efficiency and the link of giant pulses to the high-energy emission are discussed as well.

Giant pulses from the Crab pulsar

“…While there is evidence of a broadening of the pulses as they weaken in intensity, they do not appear to be as broad as standard subpulses. This finding has implications in the model derived by Petrova (2004), where a clear power-law distribution is explained, but not a weak giant population. The power-law index derived also has implications for interpreting giant pulse emission on the basis of self organised criticality (Bak et al 1987), as suggested by Cairns (2004).…”

Wide-Band Spectra of Giant Radio Pulses From the Crab Pulsar

“…The emission mechanism for the broadband GRPs may be different from the anomalous cyclotron resonance model (Lyutikov 2007) proposed for the characteristic property of the IPGRPs above 4GHz (Hankins & Eilek 2007), for which we did not detect the signal of the counterpart at P-S bands. In the induced scattering model (Petrova 2004), the intensity variation is attributed to the fluctuation of the optical depth to the induced scattering. Petrova (2004) suggested that the intensity amplification for the Crab GRPs is more efficient at the lower frequencies, which agrees with the correlation we found.…”

Giant pulses of pulsar radio emission

“…Gil and Melikidze (2005) proposed that giant pulses are generated by means of coherent curvature radiation of charged relativistic solitons associated with sparking discharge of the inner gap potential drop above the polar cap. Petrova (2004) argued that giant pulses and their substructure can be explaining in the terms of induced Compton scattering of pulsar radio emission of the plasma particles.…”