The 2009 Fermi Symposium

Unraveling the Emission Geometry of the Fermi Millisecond Pulsars

Christo Venter

Abstract:

The eight millisecond pulsars (MSPs) that have now been detected by Fermi-LAT are providing an excellent opportunity to probe the emission geometry of these ancient compact objects. As they are radio-loud, one may use the relative phase lags across wavebands to obtain constraints on the orientation and size of their radio and gamma-ray beams. We model the MSP light curves using geometric slot gap (SG), outer gap (OG), and polar cap (PC) models, in addition to a pair-starved polar cap (PSPC) model which incorporates the full General Relativistic (GR) E-field. We find that most MSP light curves are fit by SG and OG models, while PSPC is more appropriate for the remaining ones. We deduce values for inclination and observer angles (alpha and zeta), as well as flux correction factor, in each case.