Constraining the Origin of Local Positrons with HAWC TeV Gamma-Ray Observations of Two Nearby Pulsar Wind Nebulae

TL;DR

This paper uses HAWC gamma-ray observations of Geminga and B0656+14 to study electron diffusion around pulsars, constraining the origin of local positrons and their spectrum at Earth.

Contribution

It provides new constraints on electron diffusion in the local interstellar medium using TeV gamma-ray data from two nearby pulsar wind nebulae.

Findings

Electron diffusion coefficients are constrained around Geminga and B0656+14.

Morphological and spectral analyses support inverse Compton scattering as gamma-ray production mechanism.

Derived positron spectrum at Earth informs the origin of local cosmic-ray positrons.

Abstract

The HAWC Gamma-Ray Observatory has reported the discovery of TeV gamma-ray emission extending several degrees around the positions of Geminga and B0656+14 pulsars. Assuming these gamma rays are produced by inverse Compton scattering off low-energy photons in electron halos around the pulsars, we determine the diffusion of electrons and positrons in the local interstellar medium. We will present the morphological and spectral studies of these two VHE gamma-ray sources and the derived positron spectrum at Earth.