“Nuclear Astrophysics: Gamma-ray measurements from space to Earth”

Gamma rays provide a unique window on nuclear processes occurring throughout the Universe, directly tracing radioactive isotopes and matter antimatter annihilation.
In this talk, I will review key results from gamma-ray line spectroscopy in space, focusing on observations from 22 years of the now completed ESA satellite mission INTEGRAL. Measurements of radioactive isotopes, such as 26Al and 60Fe, reveal ongoing nucleosynthesis in the Galaxy and connect stellar explosions to traces found on Earth, including signatures preserved in ocean crust sediments. In this context, the long-standing puzzle of the Galactic 511 keV positron annihilation emission is also discussed.
NASA’s Compton Spectrometer and Imager (COSI) mission, scheduled for launch in 2027, is expected to significantly advance MeV measurements thanks to its increased sensitivity and imaging capabilities. I will introduce the Compton telescope concept and highlight open questions addressed by COSI, such as the role of massive stars and supernovae in Galactic feedback.
Finally, I will show how analysis and imaging techniques developed for space-based gamma-ray astronomy are now being applied on Earth, enabling isotopic imaging of radioactive residues in nuclear facilities and secondary gamma-rays from lightning discharges in the atmosphere.