Highly-Magnetized Pulsars and Integral

The complete absence of radio pulsars with periods exceeding a few seconds has lead to the popular notion of the existence of a high period death line. We have recently postulated the existence of another radio quiescence boundary at high magnetic fields ($B\gtrsim 4\times 10^{13}$G) in the upper portion of the period-period derivative diagram, a domain where no radio pulsars are observed. The origin of this high B boundary is also due to the suppression of magnetic pair creation, $\gamma\to e^{\pm}$, but mainly because of competition with the exotic QED process of magnetic photon splitting, $\gamma\to\gamma\gamma$, coupled with ground state pair creation. This mechanism could also explain the low spectral cutoff energy of the gamma-ray pulsar PSR1509-58, which lies near the high B death-line. In this paper, we summarize the hypothesis of this new ``death line,'' and discuss some subtleties of pair suppression that relate to photon polarization and positronium formation. We identify several ways in which Integral will serve as a useful tool in probing high field pulsars, given that the radio quiescence boundary is transparent to the high energy bands.