Fundamental pulsar luminosity

Abstract

We have performed a dimensional analysis of pulsar parameters on the assumption that the basic source of plasma is space-charge limited flow (as opposed to pair production) out of the ''polar cap'' regions of a rotating magnetized neutron star. We find that the pulsar power output can be scaled in terms of a fundamental ''luminosity'' determined by the mass of the positive charge carrier (m), L=32tauepsilon/sub 0/m/sup 2/c/sup 5//e/sup 2/=7.24 x 10/sup 27/ ergs s/sup -1/ (iron ions), and that this luminosity must be exceeded if the magnetic field is to exert control over the particles out to the light cylinder. If we adopt the latter as a criterion for coherent radio emission, we conclude that:1. It may be possible to model coherent radio pulsars in the laboratory (i.e., the power output can be scaled down to more acceptable power requirements by reducing m, the mass of the positive particles, either by using positrons or by somehow imposing a stationary background change and allowing only electrons to flow).2. Cohenrent radio pulsars are characterized by a minimum (cutoff) total power output (below which coherence fails) which is given approximately by L/sub 0/.3. Coherent radio pulsars apparently must produce relativistic particles. Nonrelativisticmore » scaling results automatically in loss of field control (such objects might well still be pulsars in some sense, but presumably any radiation would become increasingly incoherent).4. We derive completely parameter-free relationships whereby (a) the total current through the pulsar, (b) the injected electron energy, and (c) the total power (luminosity) in electrons are each separately determined by the total energy-loss rate from the pulsar (L/sub T/) alone.5. The major energy-loss mechanism is to electromagnetic fields, not particles, regardless of the physical parameters.« less