Synthetic pulsar light curves from global kinetic simulations and comparison with the Fermi-LAT catalog

Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France

^⋆ Corresponding author; benoit.cerutti@univ-grenoble-alpes.fr

Received: 21 August 2024
Accepted: 30 January 2025

Abstract

Context. Rotation-powered pulsars represent the main class of identified gamma-ray sources in the Galaxy. The wealth of observational data collected by the AGILE and Fermi gamma-ray space telescopes in the GeV range and by ground-based Cherenkov telescopes in the TeV band provide invaluable insights into how relativistic plasmas dissipate and accelerate particles.

Aims. Decoding the information contained in the gamma-ray pulses profile is an important step to understanding how pulsars work. In this study, we aim to put an ab initio plasma model of pulsar magnetospheres to the test, in light of the most recent gamma-ray observations in the GeV and TeV bands.

Methods. We present a new series of global particle-in-cell simulations of an inclined pulsar magnetosphere. We have reconstructed high-quality synthetic pulse profiles in the synchrotron and inverse Compton channels to study their morphology and their energy dependence in greater detail. We also performed a fit of observed light curves with the model, using the third Fermi-LAT gamma-ray pulsar catalog.

Results. Reconnection in the wind current sheet powers synchrotron and inverse Compton emission. The modeled pulse profiles reproduce some of the salient features of observed gamma-ray pulsars, including the mysterious Vela-like light curves, such as: the generic double-peaked structure, the presence of a bridge or third peak in between the main pulses, and the pulse narrowing with increasing energy. The bolometric synchrotron radiative efficiency is strictly limited by the reconnection rate.

Conclusions. Our global kinetic simulations demonstrate a good match to observed pulse profiles. Such direct comparisons will help drive and focus the development of future simulations.