Frequency-resolved radio and high-energy emission of pulsars

Université de Strasbourg, CNRS, Observatoire Astronomique de Strasbourg, UMR 7550, 67000 Strasbourg, France
e-mail: quentin.giraud@astro.unistra.fr

Received: 30 November 2020
Accepted: 9 August 2021

Abstract

Context. Pulsars are detected as broadband electromagnetic emitters from the radio wavelength up to high and very high energy in the MeV, the GeV and sometimes even in the TeV range. Multiwavelength phase-resolved spectra and light curves offer an unrivaled opportunity to understand their underlying radiation mechanisms and to localize their emission sites and therefore the particle acceleration regions.

Aims. In this paper we compute pulsar multiwavelength phase-resolved light curves and spectra, assuming that both curvature and synchrotron radiation operate from inside the magnetosphere of a rotating vacuum magnet. Radio emission arises from dipolar regions above the polar caps, whereas gamma-ray energy emanates from the slot gaps in the vicinity of the separatrix between closed and open field lines.

Methods. By integrating particle trajectories within the slot gaps, we compute energy-dependent photon sky maps in the radio band (MHz−GHz) and in the gamma-ray band (from MeV to GeV) for mono-energetic distribution functions of leptons.

Results. We obtained many details of the energy-dependent light curves and phase-resolved spectra from the radio wavelength up to the gamma-ray energies. Choosing Lorentz factors of γ ≈ 30 for the secondary plasma responsible for the radio emitting particles and γ ≈ 10⁷ for the primary beam producing gamma-ray-emitting particles limited by radiation reaction, we found realistic spectra that account for the wealth of multiwavelength pulsar observations.