Radio-to-TeV Phase-resolved Emission from the Crab Pulsar: The Annular Gap Model

TL;DR

This paper models the Crab pulsar's multi-wavelength emission from radio to TeV energies using a 3D annular gap model, successfully reproducing observed light curves and spectra by considering emission from primary and secondary particles in a single magnetic pole.

Contribution

It introduces a comprehensive 3D annular gap model that explains phase-resolved emission across multiple wavelengths from the Crab pulsar, emphasizing a single magnetic pole origin.

Findings

Multi-wavelength light curves are phase-aligned due to emission from a single magnetic pole.

Different emission regions (annular and core gaps) produce distinct pulse features.

The model reproduces observed spectra from soft X-ray to TeV energies.

Abstract

In the framework of the three-dimensional (3D) annular gap model with reasonable parameters (the magnetic inclination angle \alpha = 45 deg and the view angle \zeta = 63 deg), we first use the latest hight energy data to self-consistently calculate radio, X-ray, gamma-ray and TeV (MAGIC and VERITAS) light curves, phase-averaged spectrum and phase-resolved spectra for the Crab pulsar. It is found that the acceleration electric field and potential in the annular gap and core gap are huge enough in the several tens of neutron star radii. The pulsed emission of radio, X-ray, gamma-ray and TeV are mainly generated from the emission of primary particles or secondary particles with different emission mechanisms in the nearly similar region of the annular gap located in the only one magnetic pole, which leads to the nearly "phase-aligned" multi-wavelength light curves. The emission of peak 1 (P1) and peak 2 (P2) is originated from the annular gap region near the null charge surface, while the emission of bridge is mainly originated from the core gap region. The phase-averaged spectrum and phase-resolved spectra of the Crab pulsar from soft X-ray to TeV band are produced by four components: synchrotron radiation from CR-induced and ICS-induced pairs dominates the X-ray band to soft gamma-ray band (100 eV to 10 MeV); curvature radiation and synchrotron radiation from the primary particles mainly contribute to gamma-ray band (10 MeV to \sim 20 GeV); ICS from the pairs significantly contributes to the TeV gamma-ray band (\sim 20 GeV to 400 GeV). The multi-wavelength pulsed emission from the Crab pulsar has been well modeled with the annular gap and core gap model. To distinguish our single magnetic pole model from two-pole models, the convincing values of the magnetic inclination angle and the viewing angle will play a key role.