Statistical methods for constraining pulsar geometries via multiband light curve fitting

Abstract

The Fermi Large Area Telescope (LAT) is a high-energy satellite that operates in the Me V to Ge V band. Fermi has revolutionised pulsar physics by its clear detection of more than 200 of these objects in 1-rays. Since its launch in 2008, there have been various attempts to exploit both 1-ray and radio pulsar data to obtain constraints on the geometry and emission sites of pulsars. By concurrently fitting standard geometric model light curves onto Fermi and radio data, researchers have constrained the inclination and observer angles of a number of pulsars. At first this was done by comparing observed and modelled light curves by eye, and later via statistical approaches. Such statistical approaches are, however, complicated by the disparate error margins on the available radio and 1-ray pulsar observations. In this work, I fit modelled light curves of 16 pulsars to radio and 1-ray data both by eye and by optimising a bespoke test statistic developed by Seyffert et al. (in preparation) for combining light curves across the two wavebands, taking their disparate errors into account. I present geometrical constraints found using these approaches, and compare them with results found by Johnson et al. (2014) and Pierbattista et al. (2015) for the same pulsars.