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, highlighting the roles of leptons and hadrons in producing observable gamma rays across different energy ranges.

Contribution

It introduces a comprehensive model including hadronic processes for gamma-ray emission from PWNe near molecular clouds, applied to recent TeV sources IC443 and W41.

Findings

Low-energy gamma rays are produced by leptons accelerated near pulsars.

High-energy gamma rays above 10 TeV originate from hadrons interacting with dense matter.

High-energy emission correlates with dense cloud locations due to hadron capture.

Abstract

We consider a situation in which a pulsar (and its nebula) is formed inside or close to a high density regions of a molecular cloud. We apply a recent model for the gamma radiation of pulsar wind nebulae (PWN), which includes not only radiation processes due to injected leptons but also processes due to injection of relativistic hadrons, in order to calculate the expected gamma-ray emission from such interacting PWNe. The example calculations have been performed for two objects of this type from which directions TeV gamma-ray sources have recently been observed (IC443 and W41). We show that the gamma-ray emission below a few TeV can be produced by leptons accelerated in the past in the vicinity of the pulsars. gamma-rays with energies above ~10 TeV can be produced by hadrons interacting with the matter inside the supernova remnant and surrounding dense clouds. In contrary to the low energy TeV emission, this high energy TeV emission should be correlated with the location of dense clouds able to capture hadrons due to their strong magnetic fields.