Congruity of the Crab pulsar's gamma-ray spectrum with the spectral distribution of tightly focused caustics

TL;DR

This paper demonstrates that the gamma-ray spectrum of the Crab pulsar can be explained by a single emission mechanism related to tightly-focused caustics in the magnetosphere, unifying the entire spectrum from 100 MeV to 1 TeV.

Contribution

It introduces a novel spectral distribution function derived from superluminally moving current sheets that fits the entire gamma-ray spectrum of the Crab pulsar and other non-aligned pulsars with a single emission mechanism.

Findings

The spectrum from 10^2 to 10^6 MeV is explained by a single distribution function.

The model applies to multiple gamma-ray pulsars, not just the Crab.

Physical parameters of pulsar magnetospheres are inferred from spectral fits.

Abstract

The spectrum derived here for the most tightly-focused component of the radiation generated by the superluminally moving current sheet in the magnetrosphere of a non-aligned neutron star has a distribution function that fits the entire gamma-ray spectrum of the Crab pulsar on its own. This is the first time that the undivided breadth of this spectrum, from 10^2 to 10^6 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 gamma-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.