The complete absence of radio pulsars with periods exceeding a few seconds has lead to the popular notion of the existence of a high P "death line." In the standard picture, beyond this boundary, pulsars with low spin rates cannot accelerate particles above the stellar surface to high enough energies to initiated pair cascades through curvature radiation, and the pair creation needed for radio emission is strongly suppressed. In this paper we postulate the existence of another pulsar "death line," corresponding to high magnetic fields B in the upper portion of the period-period derivative diagram, a domain where few radio pulsars are observed. The origin of this high B boundary, which occurs when B becomes comparable to or exceeds 10 TeraGauss, is again due to the suppression of magnetic pair creation, but in this instance, primarily because of ineffective competition with the exotic QED process of magnetic photon splitting, which has recently been invoked to explain the low energy cutoff in the spectrum of the gamma-ray pulsar PSR1509-58. This paper describes the origin, shape and position of the new "death line," above which pulsars are expected to be radio quiet, but perhaps still X-ray and gamma-ray bright. Guidelines for moderate to high B pulsar searches at radio wavelengths and also in the soft and hard gamma-ray bands are presented.
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 1997