Constraining pulsar gap models with light-curve shapes of a simulated gamma-ray pulsar population

TL;DR

This study uses population synthesis and light-curve analysis of gamma-ray pulsars to constrain models of pulsar magnetospheric emission regions, revealing that observed pulsar light curves retain key geometrical information.

Contribution

The paper introduces new simulations and light-curve analysis methods to better constrain pulsar gap models and magnetospheric geometry.

Findings

Light-curve shapes retain geometrical information of pulsar populations.

Simulations suggest gamma-ray emission originates from high-altitude regions.

Light-curve analysis constrains pulsar beam geometry and orientation.

Abstract

The Fermi Gamma-Ray Space Telescope has discovered many gamma-ray pulsars, both as radio-loud objects and radio-quiet or radio-weak pulsars that have been identified through blind period searches. The latter presumably have gamma-ray beams originating from high altitudes in the magnetosphere, resulting in little or no overlap with the radio beam. The exponential cut-off of the emission at high energy also points to a medium- or high-altitude origin of the gamma rays. Population synthesis offers means to study two complementary aspects of the gamma-ray pulsar population: energetics and light curve morphology. The latter (peak multiplicity, position, separation, asymmetries, ...) can be used to constrain the beam(s) geometry (their origin within the open magnetosphere, evolution of the radiating region with pulsar power and age, ...). It can also be used to constrain the obliquity and orientation of a pulsar in the framework of a given accelerator model. We present preliminary results from new simulations and light-curve analysis that indicate that the sample of Fermi pulsars retains much of the geometrical information of the parent gamma-ray pulsar population.