A SEARCH FOR RADIO-QUIET GAMMA-RAY PULSARS IN THE EGRET DATA

We are searching for radio-quiet gamma-ray pulsars among the brightest unidentified EGRET point sources. This investigation utilizes the com putational resources of the Center for Advanced Computing Research at Caltech to compute Gigapoint power spectra. Multiple frequency derivat ives are searched by accelerating event times before computing the Fou rier transform. We demonstrate that such a search detects the pulsatio n of radio-quiet Geminga with 10(-12) significance directly from 6 day s of EGRET data. The remaining unidentified EGRET sources have substan tially less signal to noise to support a periodicity search, but can b e detected with similar to 3 weeks of exposure if the pulsar lightcurv e has sufficient harmonic content. Only upper limits have been obtaine d to date. We demonstrate that the error in transforming EGRET event t imes to the solar system barycenter caused by the inaccuracy of the EG RET position results in a detection at a frequency and frequency deriv ative different from the true values, but harmonic power is not lost.