MeV-GeV Gamma-Ray Astrophysics in the Multimessenger Era
A new review paper published in Physics and the Cosmos surveys the scientific landscape of MeV-to-GeV gamma-ray astrophysics, tracing its history from 1950s theoretical predictions to modern space- and ground-based observatories. The authors highlight a persistent sensitivity gap in the few-hundred-keV to few-GeV energy range that limits progress on nucleosynthesis, dark matter, positron annihilation, and electromagnetic counterparts to gravitational waves and neutrinos. Closing this 'MeV gap' is framed as a key priority for advancing multimessenger astronomy.
A review article by Alessandro De Angelis and colleagues, submitted to arXiv and published in Physics and the Cosmos (2026), provides a comprehensive overview of gamma-ray astrophysics spanning nine orders of magnitude in photon energy, from sub-MeV to PeV scales. The paper traces the field's development from pioneering theoretical work in the 1950s through the first space-based gamma-ray detections in the 1960s to the current era of multimessenger astronomy incorporating neutrino and gravitational-wave observations. Central to the review is the identification of the 'MeV gap'—the energy range from a few hundred keV to a few GeV—where current instruments lack the sensitivity needed to fully address major open questions. Scientific topics constrained by this gap include stellar nucleosynthesis, cosmic positron annihilation, the physics of explosive transients, dark-matter signatures, and the detection of electromagnetic counterparts to high-energy astrophysical events. The authors survey both the motivations for next-generation gamma-ray missions and the programmatic efforts underway to address this sensitivity limitation.
What's missing
The review's own limitations are not detailed in the abstract: it is unclear which specific proposed missions or instruments the authors evaluate as most promising for closing the MeV gap, what timescales or funding landscapes are discussed, and whether the paper includes quantitative sensitivity projections for future detectors.
What different sources said
- arXiv physicsCenter
MeV-GeV Gamma-Ray Astrophysics in the Multimessenger Era
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