Gamma-Ray Emission from PWNe Interacting with Molecular Clouds

TL;DR

This paper models gamma-ray emission from pulsar wind nebulae interacting with molecular clouds, explaining observed TeV gamma-ray sources IC443 and W41 through particle acceleration and diffusion processes.

Contribution

It extends a time-dependent PWN gamma-ray model to include interactions with molecular clouds, linking emission features to pulsar birthplaces and dense cloud regions.

Findings

Low energy TeV emission correlates with pulsar birthplace and dense radiation regions.

High energy TeV emission correlates with dense clouds capturing high energy hadrons.

Model explains observed gamma-ray features of IC443 and W41.

Abstract

We consider a situation in which a pulsar is formed inside or close to a high density region of a molecular cloud. Right after birth, the pulsar was very active and accelerated hadrons and leptons to very high energies. Hadrons diffuse through the supernova remnant (SNR) and some of them are trapped in the nearby cloud interacting with the matter. We extend a recent time-dependent model for the gamma-radiation of pulsar wind nebulae (PWNe) to describe this more complicated astrophysical scenario. The example calculations have been performed for two objects, IC443 and W41, which have recently been discovered as sources of TeV gamma-rays. In this model the low energy TeV emission should be correlated with the birth place of the pulsar and the region of dense soft radiation rather than with its present position, provided that the injection rate of relativistic particles into the PWNa has been much more efficient at early times. The high energy TeV emission should be correlated with the location of dense clouds which were able to capture high energy hadrons due to their strong magnetic fields.