Several satellites dedicated to high-energy astrophysics, including the Italian AGILE (Astrorivelatore Gamma ad Immagini LEggero) satellite, detected the most energetic Gamma-Ray Burst (GRB) ever recorded on January 1, 2022. The event, known as GRB 220101A, occurred when the universe was approximately 1.3 billion years old and took place over 12 billion light years away. The AGILE satellite provided valuable data for the first detailed study of this “New Year’s Burst,” which was published in the Astrophysical Journal on July 15.
Alessandro Ursi, the first author of the article and a researcher at INAF, described the event as exceptional. While AGILE has previously observed intense GRBs like GRB 080916C and GRB 160625B, events of this magnitude are rare. The energy emitted by GRB 220101A is the highest ever recorded for a GRB, as estimated by its equivalent isotropic energy.
The scientific community quickly became interested in this record-breaking event, leading to the release of more than twenty communications reporting observations from other space missions and ground-based observatories.
Ursi explained that AGILE’s data allowed for the initial characterization of the prompt phase of GRB 220101A, which involves high-energy radiation emitted during the initial shocks within the central engine. AGILE’s detectors, which cover a range of energies from X-ray to gamma-ray, provided a comprehensive overview of the event’s temporal evolution and energetics. By combining AGILE’s data with public data from the Swift satellite, researchers were also able to study the “afterglow” emission, which is the delayed emission at lower energies caused by interactions with the surrounding interstellar medium. This analysis provided valuable information about the environment in which the energetic event occurred.
AGILE’s capabilities extend beyond GRB observations. The satellite has also contributed significantly to the study of high-energy phenomena on Earth, such as Terrestrial Gamma-Ray Flashes (TGFs). The AGILE mission’s project scientist and data center coordinator, Carlotta Pittori, highlighted the publication of all TGFs observed by AGILE up until December 31, 2021, on the ASI SSDC data center website. These publications provide additional details and information compared to the original catalog released in 2020.
Overall, AGILE continues to prove itself as an exceptional instrument for observing cosmic phenomena like GRBs and contributing to the understanding of high-energy events both in space and on Earth.