Intrinsic Variability and Field Statistics for the Vela Pulsar: 3. Two-Component Fits and Detailed Assessment of Stochastic Growth Theory

Abstract

The variability of the Vela pulsar (PSR B0833-45) corresponds to well-defined field statistics that vary with pulsar phase, ranging from Gaussian intensity statistics off-pulse to approximately power-law statistics in a transition region and then lognormal statistics on-pulse, excluding giant micropulses. These data are analyzed here in terms of two superposed wave populations, using a new calculation for the amplitude statistics of two vectorially-combined transverse fields. Detailed analyses show that the approximately power-law and lognormal distributions observed are fitted well at essentially all on-pulse phases by Gaussian-lognormal and double-lognormal combinations, respectively. These good fits, plus the smooth but significant variations in fit parameters across the source, provide strong evidence that the approximately power-law statistics observed in the transition region are not intrinsic. Instead, the data are consistent with normal pulsar emission having lognormal statistics at all phases. This is consistent with generation in an inhomogeneous source obeying stochastic growth theory (SGT) and with the emission mechanism being purely linear (either direct or indirect). A nonlinear mechanism is viable only if it produces lognormal statistics when suitably ensemble-averaged. Variations in the SGT fit parameters with phase imply that the radiation is relatively more variable near the pulse edges than near the center, as found in earlier work. In contrast, Vela's giant micropulses come from a very restricted phase range and have power-law statistics with indices ($6.7\pm 0.6$) not inconsistent with nonlinear wave collapse. These results imply that normal pulses have a different source and generation mechanism than giant micropulses, as suggested previously on other grounds.

10 pages and 14 figures. Accepted by Monthly Notices of the Royal Astronomical Society in April 2003

References in corpus (7)

• Giant Pulses from the Millisecond Pulsar B1821-24
• High time-resolution observations of the Vela pulsar
• High-resolution single-pulse studies of the Vela Pulsar
• Intrinsic Variability of the Vela Pulsar: Lognormal Statistics and Theoretical Implications
• A search for giant pulses in Vela-like pulsars
• Intrinsic Variability and Field Statistics for the Vela Pulsar: 2. Systematics and Single-Component Fits
• On the reliability of peak-flux distributions, with an application to solar flares

Cited by in corpus (9)

• The High Time Resolution Universe Survey - V: Single-pulse energetics and modulation properties of 315 pulsars
• Simultaneous multi-frequency single-pulse properties of AXP XTE J1810-197
• Properties and Interpretations of Giant Micropulses and Giant Pulses from Pulsars
• Timing, polarimetry and physics of the bright, nearby millisecond pulsar PSR J0437-4715 - a single-pulse perspective
• Intrinsic Variability and Field Statistics for the Vela Pulsar: 2. Systematics and Single-Component Fits
• On the Excess Dispersion in the Polarization Position Angle of Pulsar Radio Emission
• Pulse to pulse flux density modulation from pulsars at 8.35 GHz
• Single-pulse analysis and average emission characteristics of PSR J1820-0427 from observations made with the MWA and uGMRT
• Hyperbolic limit on the early arrival time of bright pulses from PSR~J0835$-$4510 (Vela)