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F.P. Gavriil (McGill University), S.M. Ransom, M.S.E. Roberts (McGill University/MIT), V.M. Kaspi (McGill University), B.M. Gaensler (Harvard-Smithsonian CfA), E.V. Gotthelf (Columbia University), S.S. Murray, P.O. Slane (Harvard-Smithsonian CfA)
The X-ray Pulsars PSR J1811-1925 and PSR J0205+6559, in the historical supernova remnants G11.2-0.3 and 3C 58 respectively, have characteristic ages much greater than the ages of their remnants. This likely implies that their current spin periods, ~65 ms, are close to their birth spin period. Alternatively, these pulsars may have unusually high braking indices. Despite the striking similarities in the pulsar's spin parameters and historical ages, the two have very different pulse shapes and X-ray luminosities, which could imply different emission mechanisms and/or geometries. We report here on regular Rossi X-ray Timing Explorer/ Proportional Counting Array (RXTE/PCA) timing observations of these pulsars that were designed to measure their braking indices. For PSR J1811-1925, we provide a preliminary phase-coherent timing solution which includes a significant \ddot{\nu}. The braking index we measure is >> 3. This could be a manifestation of timing noise; further observations can test this. For PSR J0205+6559, excessive timing noise has made long-term phase coherent timing of this pulsar difficult, but preliminary results imply a braking index significantly greater than 3 as well. We also report on a preliminary analysis of the phase-averaged and phase-resolved spectra of both sources.
This work is funded by NSERC, CIAR, NASA and a McGill University Tomlinson Fellowship.
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The author(s) of this abstract have provided an email address for comments about the abstract: gavriil@physics.mcgill.ca
Bulletin of the American Astronomical Society,
35#2
© 2003. The American Astronomical Soceity.