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LCO Astronomers Study the Largest Gamma Ray Burst Ever Seen

Apr 21, 2023

Combined Hubble Space Telescope images of the GRB 221009A field, observed on 2022 December 4. Note the clear appearance of an underlying host galaxy, with a disk-like shape. Image Credit:  The Astrophysical Journal Letters (2023).

On October 9, 2022, space-based detectors picked up the signal of the brightest Gamma Ray Burst ever detected. The event, GRB 221009A, is 70 times brighter than anything previously recorded. Follow-up observations have been performed with space and Earth telescopes, in both radio and optical wavelengths. Teams of scientists around the world have been studying the data in an effort to describe this extraordinary event.

A GRB is a bright blast of gamma rays, the most energetic radiation that exists in the universe. The leading theory is that a massive, rapidly rotating star collapses in a special kind of supernova, sometimes called a hypernova. The explosion sends focused jets of gamma rays outward. When a GRB is nearby, astronomers usually can spot the supernova responsible for it by looking for it with optical telescopes.

In late March, a study was published in the Astrophysical Journal Letters detailing the search for a supernova signal in GRB 221009A. The study includes data from optical telescopes around the world, including the LCO observatory in Maui.

The head of the Global Supernova Project, Dr. Andy Howell and a group of scientists that includes present and former LCO postdoctoral researchers and graduate students contributed to the project. The paper concludes that the data do not present a clear sign of a supernova, while the possibility does exist of a supernova that occurred at an energy level too low to be detected.

Dr. Howell is happy that data from LCO were applied to this project and is looking forward to continued work on GRB 221009A. “This is what Las Cumbres Observatory was built for – when something happens in the sky, we can point our telescopes immediately and follow that exciting event around the clock. And the results are interesting – how can the GRB that is the brightest of all time in Gamma Rays not produce a bright supernova? Maybe the star collapsed to make a black hole and the supernova was a dud. We’ll be scratching our heads over this for a long time.”