Implications of emission zone limits for the Ruderman-Sutherland pulsar model

Abstract

view Abstract Citations (24) References (18) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Implications of emission zone limits for the Ruderman-Sutherland pulsar model Matese, J. J. ; Whitmire, D. P. Abstract In the Ruderman-Sutherland (RS) pulsar model the frequency at which coherent radiation is emitted depends upon the source location, ν = ν(r). In the oblique rotator version of this model the time-averaged tangential velocities of the magnetosphere sources must increase linearly with radius, and this leads to a frequency-dependent aberration and retardation time delay in which higher frequencies lag behind lower frequencies. As previously noted by Cordes, within the context of a given model which specifies v(r), the absence of any anomalous time delay in dispersion measurements allows limits to be placed on the radial position of the source of a given frequency. In this paper we (a) give a time-delay analysis (similar to that of Cordes) appropriate for the RS model and show that existing dispersion measurements are incompatible with RS emission radii (r ≳ 108 cm), and (b) consider the implications of these limits for the basic RS emission mechanism. If the basic RS emission mechanism is applicable to pulsars, we find that the most plausible modification consistent with the dispersion data is a reduction in the low-energy plasma density by a factor ∼10-4 to 10-5. This has the effect of bringing the radio emission zone closer to the stellar surface, thereby making the model consistent with the dispersion data. In addition, this modification results in a significant decrease in the predicted maximum cone angle and an increase in the predicted maximum frequency by factors which bring these predictions more in line with observation. We also consider implications of a reduced plasma density for radio luminosity. Publication: The Astrophysical Journal Pub Date: January 1980 DOI: 10.1086/157662 Bibcode: 1980ApJ...235..587M Keywords: Magnetohydrodynamics; Pulsars; Stellar Atmospheres; Stellar Models; Magnetospheres; Plasma Density; Radio Emission; Time Lag; Astrophysics full text sources ADS |