AMEGO, the All-sky Medium Energy Gamma-ray Observatory, is an Astrophysics Probe mission concept designed to explore the MeV sky.
AMEGO provides three new capabilities in MeV astrophysics: sensitive continuum spectral studies, polarization, and nuclear line spectroscopy. The primary optimization for AMEGO is continuum sensitivity across a broad energy range. The extremely diverse science reach for AMEGO (as summarized in this figure) is greatly enhanced by adding polarization and nuclear line spectroscopy.
The MeV domain is one of the most underexplored windows on the Universe. From astrophysical jets and extreme physics of compact objects to a large population of unidentified objects, fundamental astrophysics questions can be addressed by a mission that opens a window into the MeV range. The time is right for an MeV mission. Fermi-LAT observations at GeV energies have opened a window to a rich and varied ensemble of astrophysical sources, and demonstrate the promise of an equally rich return from opening the MeV band. Secondly, we are at the dawn of the multimessenger era, with the recent discovery of high energy astrophysical neutrinos by IceCube and the first direct observation of gravitational waves by LIGO. By virtue of its focus on extreme environments, a medium energy gamma-ray surveyor is an excellent partner in these new scientific endeavors.
An MeV gamma-ray surveyor probe mission has a unique capability to provide sensitive coverage of both the Compton (0.2 - 10 MeV) and pair conversion (10 MeV - 10 GeV) regimes. This allows a single mission to cover the entire gap between the current generation of hard X-ray instruments (like NuSTAR) and the Fermi-LAT.
Enhancing the performance of the calorimeter for Compton events will open up new capabilities for MeV spectroscopy. AMEGO will address three key performance directions in MeV astrophysics. We will have an outstanding continuum sensitivity over a wide energy range and field of view to continue Fermi-LAT-like science down to lower energies. In addition we add a substantial science case from nuclear line astrophysics.
A smaller scale mission could not cover the entire energy range, and would necessitate a choice between a wide-field continuum sensitivity and nuclear line spectroscopy. With AMEGO we can do both. AMEGO will have the very broad science menu appropriate for a probe class mission. As an all-sky surveyor it will collect data on all MeV sources in the sky and will provide a service to the whole astrophysical community