Hunting FRBs at high energy with AGILE

**Introduction:**What are Fast Radio Bursts (FRBs)? These millisecond bursts from distant galaxies have astrophysicists intrigued. We explore repeating FRBs (R-FRBs) and theories about their origins, including magnetars.**AGILE's High-Energy Hunt:**The Italian AGILE satellite, with its SuperAGILE (18-60 keV), MCAL (0.35-100 MeV), and GRID (0.03-50 GeV) detectors, searched for X- and gamma-ray counterparts to a sample of R-FRBs.**The Search and Non-Detection:**AGILE observed several bursts from R-FRBs with low dispersion measure (DMexc < 300 pc cm−3). However, no astrophysical signals were identified in the X- and gamma-ray bands.**Upper Limits and Magnetar Models:**The study derived upper limits on the flux, particularly with MCAL, which are now the most stringent in the 0.4-30 MeV range. Researchers compared these findings to the galactic magnetar SGR 1935+2154 (the source of FRB 200428) to test magnetar emission models for FRBs.**Key Findings:*** **No high-energy counterparts were detected by AGILE for the observed R-FRB sample**.* **Stringent upper limits were placed on high-energy emission**, especially by MCAL.* The study compared R-FRB energies with those extrapolated from **SGR 1935+2154**, providing constraints on the magnetar model.**Conclusion:**While AGILE didn't detect high-energy counterparts for this R-FRB sample, its observations provide valuable constraints for theoretical models, especially those involving magnetars. The archival AGILE data still holds potential for future discoveries.**Reference:**Casentini, C., Verrecchia, F., Tavani, M., Pilia, M., & Pacciani, L. (2025). AGILE observations of a sample of repeating Fast Radio Burst sources. *Draft version March 13, 2025*.Acknowledements: Podcast prepared with Google/NotebookLM. Illustration credits: AGILE collaboration