14 October 2022, astronomers using the Gemini South telescope in Chile operated by NSF’s NOIRLab observed the unprecedented aftermath of Gamma-Ray Burst GRB221009A, one of the most powerful explosions ever recorded. This record-breaking event, which was first detected on 9 October 2022 by orbiting X-ray and gamma-ray telescopes, occurred 2.4 billion light-years from Earth and was most likely caused by a supernova explosion that gave birth to a black hole.
A massive cosmic explosion sparked a frenzy of activity among astronomers all over the world as they raced to study the aftermath of one of the closest and possibly most energetic gamma-ray bursts (GRB) ever observed. Observations made recently by two independent teams using the Gemini South telescope in Chile—one of the twin telescopes of the International Gemini Observatory operated by NSF’s NOIRLab—targeted the bright, glowing remnants of the explosion, which most likely heralded the birth of a black hole.
The GRB, identified as GRB 221009A, occurred approximately 2.4 billion light-years away in the direction of the constellation Sagitta. It was first detected the morning of 9 October by X-ray and gamma-ray space telescopes, including NASA’s Fermi Gamma-ray Space Telescope, Neil Gehrels Swift Observatory, and the Wind spacecraft.
The agility and responsiveness of Gemini’s infrastructure and staff are hallmarks of our observatory and have made our telescopes go-to resources for astronomers studying transient events.
Janice Lee
As word of this discovery spread, two teams of astronomers collaborated closely with Gemini South staff to obtain the earliest possible observations of the afterglow of this historic explosion.
Two Rapid Target of Opportunity imaging observations were conducted in the early morning hours of Friday, 14 October, by two independent teams of observers led by graduate students Brendan O’Connor (University of Maryland/George Washington University) and Jillian Rastinejad (Northwestern University). The observations happened just minutes apart. The FLAMINGOS-2 instrument, a near-infrared imaging spectrograph, was used for the first observation. The Gemini Multi-Object Spectrograph was used in the other observation (GMOS).
The teams now have access to both datasets for their analyses of this energetic and evolving event.
“The exceptionally long GRB 221009A is the brightest GRB ever recorded and its afterglow is smashing all records at all wavelengths,” said O’Connor. “Because this burst is so bright and also nearby, we think this is a once-in-a-century opportunity to address some of the most fundamental questions regarding these explosions, from the formation of black holes to tests of dark matter models.”
Thanks to the fast reaction of observers and staff, combined with the use of Gemini Director’s Discretionary Time and efficient data-reduction software like Gemini’s DRAGONS “FIRE” (Fast Initial Reduction Engine), this image was quickly produced soon after the observations.
“The agility and responsiveness of Gemini’s infrastructure and staff are hallmarks of our observatory and have made our telescopes go-to resources for astronomers studying transient events,” said Gemini Chief Scientist Janice Lee.
Already, communications have been sent to fellow astronomers via the NASA Gamma-ray Coordinates Network, whose archive is rapidly filling up with reports from around the world. Astronomers believe it represents the collapse of a star many times the mass of our Sun, which ignites an extremely powerful supernova and gives birth to a black hole 2.4 billion light-years away.
“In our research group, we’ve been referring to this burst as the ‘BOAT’, or Brightest Of All Time, because when you look at the thousands of bursts gamma-ray telescopes have been detecting since the 1990s, this one stands apart,” said Rastinejad. “Gemini’s sensitivity and diverse instrument suite will help us to observe GRB221009A’s optical counterparts to much later times than most ground-based telescopes can observe. This will help us understand what made this gamma-ray burst so uniquely bright and energetic.”
When black holes form, they drive powerful jets of particles that are accelerated to nearly the speed of light. These jets then piece through what remains of the progenitor star, emitting X-rays and gamma rays as they stream into space. If these jets are pointed in the general direction of Earth, they are observed as bright flashes of X-rays and gamma rays.
Another such bright gamma-ray burst may not appear for decades or even centuries, and the case is still evolving. Other extraordinary reports of disturbances in the Earth’s ionosphere caused by the energetic radiation from the GRB221009A event are noteworthy. Scientists are also puzzled as to how 18 TeV (tera-electron-volt) photons observed with the Chinese Large High Altitude Air Shower Observatory could defy our standard understanding of physics and survive their 2.4 billion-year journey to Earth.
