Outer-gap vs. Slot-gap Models for Pulsar High Energy Emissions: The Case of the Crab Pulsar

TL;DR

This paper analytically compares outer-gap and slot-gap models for pulsar gamma-ray emissions, showing that the outer-gap model better reproduces observed fluxes in the Crab pulsar, with implications for understanding pulsar emission mechanisms.

Contribution

It introduces an analytical framework linking gamma-ray flux to pulsar parameters and evaluates the effectiveness of outer-gap and slot-gap models for the Crab pulsar.

Findings

Outer-gap model reproduces observed GeV fluxes.

Slot-gap model accounts for at most 20% of observed flux.

Gamma-ray flux proportional to spin-down flux and gap thickness cubed.

Abstract

We analytically examine the capabilities of rotation-powered pulsars as the sources of gamma-rays and show that their phase-averaged gamma-ray flux is proportional to the product of the spin-down flux and the gap trans-field thickness cubed irrespective of the emission models. Applying the scheme to the Crab pulsar, we demonstrate that the outer-gap model reproduces the observed GeV fluxes and that the slot-gap model reproduces at most twenty per cent of the observed fluxes because of the small trans-field thickness. An implication on the relationship between the gamma-ray and the spin-down fluxes is discussed.