Congruity of the Crab Pulsar’s γ-ray spectrum with the spectral distribution of tightly focused caustics

Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
e-mail: ardavan@ast.cam.ac.uk

Received: 8 December 2022
Accepted: 15 February 2023

Abstract

The spectrum derived here for the most tightly focused component of the radiation generated by the super-luminally moving current sheet in the magnetosphere of a non-aligned neutron star has a distribution function that fits the entire γ-ray spectrum of the Crab Pulsar on its own. This is the first time that the undivided breadth of this spectrum, from 10² to 10⁶ MeV, is not only described by a single distribution function but is also explained by means of a single emission mechanism. To illustrate that the derived function describes the spectral distribution of the high-energy emission from any non-aligned neutron star, we analyse, in addition, the spectra of two other γ-ray pulsars for which sufficiently large datasets are available: PSR J0101−6422 and PSR J1709−4429. From the connection between the parameters of the fitted spectra and the physical characteristics of their sources, we moreover infer certain attributes of the magnetospheres of the analysed pulsars: the angle between the magnetic and spin axes of their central neutron stars, the scale factor of the electric current density that is associated with their current sheet, and the privileged latitudinal direction (relative to the spin axis) in which they are observed.