Unveiling the Fermi Bubbles origin with MeV photon telescopes

TL;DR

This paper investigates how MeV photon telescopes can help determine the origin of the Fermi Bubbles by assessing their sensitivity to extended gamma-ray emissions, aiding in distinguishing emission mechanisms.

Contribution

It provides a methodology to evaluate the sensitivity of current and future MeV telescopes to the Fermi Bubbles' emission, facilitating the identification of their primary emission processes.

Findings

COMPTEL can detect the FB extended emission.

COSI shows promising sensitivity for FB observations.

Future telescopes like AMEGO-X could significantly improve detection capabilities.

Abstract

The Fermi Bubbles (FB) are a pair of large-scale ellipsoidal structures extending above and below the Galactic plane almost symmetrically aligned with the Galactic Center. After more than 10 years since their discovery, their nature and origin remain unclear. Unveiling the primary emission mechanisms, whether hadronic or leptonic, is considered the main tool to shed light on the topic. We explore the potential key role of MeV observations of the FB and we provide a recipe to determine the sensitivity of Compton and Compton-pair telescopes to the extended emission of the FB. We illustrate the capabilities of the Imaging Compton Telescope COMPTEL, the newly selected NASA MeV mission COSI (Compton Spectrometer and Imager), as well as the expectations for a potential future Compton-pair telescope such as AMEGO-X (All-sky Medium Energy Gamma-ray Observatory eXplorer).