Constraints on the Emission Geometries of Gamma-ray Millisecond Pulsars Observed with the Fermi Large Area Telescope

Understand

Millisecond pulsars (MSPs) have been established as a class of high-energy ($\geq$0.1 GeV) emitters with the Large Area Telescope (LAT) aboard the \emph{Fermi Gamma-ray Space Telescope}.

• Most MSP gamma-ray light curves display sharp peaks indicative of thin accelerating gaps, suggesting copious pair-creation in the open volume.
• MSP gamma-ray and radio light curves have been simulated using geometric outer-gap (OG), slot-gap/two-pole caustic (TPC), and pair-starved polar cap gamma-ray models and either a hollow-cone beam or altitude-limited, outer-magnetospheric gap radio model, all assuming a vacuum retarded dipolar magnetic field geometry.
• A Markov chain Monte Carlo maximum likelihood technique has been developed to find the best-fit model parameters for nineteen MSPs using data from the LAT and various radio observatories.