Detection of the Characteristic Pion-Decay Signature in the Molecular Clouds

TL;DR

This study analyzes Fermi-LAT data to detect a characteristic pion-decay signature in molecular clouds, providing direct evidence for the hadronic origin of their gamma-ray emission.

Contribution

It presents the first significant detection of the pion-decay feature in molecular clouds, confirming the hadronic origin of gamma-ray emission in these regions.

Findings

Detection of the pion-decay signature in Orion A and B

Evidence supporting hadronic processes in molecular cloud gamma-ray emission

Analysis of 9-year Fermi-LAT data confirming theoretical predictions

Abstract

The $\gamma$-ray emission from molecular clouds is widely believed to have a hadronic origin, while unequivocal evidence is still lacking. In this work, we analyze the Fermi-LAT Pass 8 publicly available data accumulated from 2008 August 4 to 2017 June 29 and report the significant detection of a characteristic $\pi^0$-decay feature in the $\gamma$-ray spectra of the molecular clouds Orion A and Orion B. This detection provides a direct evidence for the hadronic origin of their $\gamma$-ray emission.