TeV Gamma Rays from Geminga and the Origin of the GeV Positron Excess

TL;DR

The paper discusses how TeV gamma-ray observations of Geminga suggest it is an ancient cosmic-ray source that could explain the observed positron excess, and proposes testable predictions for future experiments.

Contribution

It links TeV gamma-ray emission from Geminga to its role as a cosmic-ray accelerator responsible for the positron excess, providing new insights into cosmic-ray origins.

Findings

Detection of extended multi-TeV gamma-ray emission from Geminga.

Implication of Geminga as an ancient cosmic-ray accelerator.

Predictions for gamma-ray and electron/positron experiments to test this hypothesis.

Abstract

The Geminga pulsar has long been one of the most intriguing MeV-GeV gamma-ray point sources. We examine the implications of the recent Milagro detection of extended, multi-TeV gamma-ray emission from Geminga, finding that this reveals the existence of an ancient, powerful cosmic-ray accelerator that can plausibly account for the multi-GeV positron excess that has evaded explanation. We explore a number of testable predictions for gamma-ray and electron/positron experiments (up to ~100 TeV) that can confirm the first "direct" detection of a cosmic-ray source.