Pulsar gamma-ray emission in the radiation reaction regime

Abstract

Since the era of the Fermi/LAT and atmospheric Cerenkov telescopes, pulsars are known to emit high and very high-energy photons, in the MeV-GeV range and sometimes up to TeV. To date, it is still unclear where and how these photons are produced. Nevertheless gamma-ray photons require particle acceleration to ultra-relativistic speeds. In this paper, we compute single particle trajectories for leptons in an arbitrary strong electromagnetic field in the so-called radiation reaction limit. In this picture, particle velocity only depends on the local electromagnetic field which we assume to follow the vacuum dipole rotator. From this velocity field, we compute the curvature radiation spectrum and light-curves. Sky maps and phase-resolved spectra are then deduced accounting for realistic pulsar periods and magnetic field strengths. Emission sites within the pulsar magnetosphere where most of radiation emanates are then localized. For standard parameters of millisecond and normal pulsars, we show that a break in the spectrum occurs at several GeV in agreement with the Fermi/LAT second pulsar catalogue. A sample of representative phase-resolved spectra and sky-maps are shown. A pair multiplicity of several tenths to several thousands is required to account for the total gamma-ray luminosity. Moreover depending on the geometry, single or double-peaked light-curves are found. Our model shows that minimalist assumptions are already able to reproduce salient features of pulsar emission.

Accepted for publication in MNRAS

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Cited by in corpus (12)

• The Third Fermi Large Area Telescope Catalog of Gamma-ray Pulsars
• The Thousand-Pulsar-Array programme on MeerKAT IV: Polarisation properties of young, energetic pulsars
• Three-dimensional dissipative pulsar magnetospheres with Aristotelian electrodynamics
• Radiative pulsar magnetospheres: aligned rotator
• Dynamics of ultrarelativistic charged particles with strong radiation reaction. I. Aristotelian equilibrium state
• Poynting flux transport channels formed in polar cap regions of neutron star magnetospheres
• Modelling the broadband emission from the white dwarf binary system AR Scorpii
• A new radiation reaction approximation for particle dynamics in the strong field regime
• Dynamics of ultrarelativistic charged particles with strong radiation reaction. II. Entry into Aristotelian equilibrium
• Origin of radio polarization in pulsar polar caps
• The Effect of Pulsar Geometry on the Observed Gamma-ray Spectrum of Millisecond Pulsars
• The pulsar gamma-ray emission from the high-resolution dissipative magnetospheres