These bursts are characterized by an initial gamma-ray flare and a longer-lasting “afterglow” that typically emits in X-rays, ultraviolet, radio, and other longer wavelengths. In the early morning hours of October 14, 2022, two independent teams of astronomers using the Gemini South telescope observed the aftermath of a GRB named GRB221009A. Located 2.4 billion light-years away in the constellation Sagitta, this event was perhaps the closest and most powerful explosion ever recorded and was likely triggered by a supernova that gave birth to a black hole. Longer-duration GRBs occur when massive stars go supernova, creating a remnant black hole and blowing away their outer layers. The force of this explosion creates powerful jets as the ejected material accelerates to nearly the speed of light, pushing through the debris and emitting X-rays and gamma rays as they reach further into space. If these jets are traveling in the general direction of Earth, astronomers will observe them as bright flashes of X-rays and gamma rays. Using data from some of the most powerful telescopes on Earth and in space, astronomers have made unprecedented observations of a nearby GRB. Remove all ads on Universe Today Join our Patreon for just $3! Get the ad-free experience of a lifetime GRB221009A was first spotted on the morning of October 9, 2022, by X-ray and gamma-ray space telescopes – including NASA’s Fermi Gamma-ray Space Telescope, the Neil Gehrels Swift Observatory and the Wind spacecraft. Almost immediately afterward, observatories around the world raced to make further observations and determine what happened. Using the Gemini South telescope (operated by NOIRLab), two independent teams made rapid Target of Opportunity (ToO) observations of the event’s strong afterglow. The teams were led by Brendan O’Connor, graduate observational astronomer of the University of Maryland and George Washington University, and Jillian Rastinejad, Ph.D. student at Northwestern University’s Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA). The two teams obtained the earliest possible observations of the afterglow within minutes, using Gemini South’s FLAMINGOS-2 near-infrared imager and the Gemini Multi-Object Spectrograph (GMOS), respectively. As Rastinejad explained in a recent NOIRLab press release, their combined data sets produced a picture of what could be the brightest GRB ever observed: “In our research team we referred to this burst as the ‘BOAT’ or Brightest of All Time, because when you look at the thousands of bursts detected by gamma-ray telescopes since the 1990s, this one stands out. Gemini’s sensitivity and variety of instruments will help us observe GRB221009A’s optical counterparts at 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.” The speed with which the teams made their observations is a testament to the Gemini Observatory’s data reduction infrastructure and software – including the Fast Initial Reduction Engine (FIRE) and Data Reduction for Astronomy from Gemini Observatory North and South (DRAGONS) platforms. Shortly thereafter, NASA’s Gamma-ray Coordinate Network began to flood with reports from observatories around the world. Based on the available data, scientists believe that the GRB was the result of the collapse of a star many times the mass of our Sun that gave birth to a black hole. Artist’s rendering of two merging neutron stars. Credit: Dana Berry, SkyWorks Digital, Inc. Additionally, data from this event may help solve an ongoing mystery about GRBs. While most gamma-ray bursts have been observed in distant galaxies, some appear as solitary flashes from intergalactic space. This has raised questions about the true origin and distances of GRBs, with many astronomers suggesting that some short bursts originate in the intergalactic medium (IGM). However, these results suggest that short GRBs may have been more common in the past than expected. The research teams reached this conclusion after consulting data on the 120 short GRBs observed by the two main instruments at NASA’s Swift Observatory – the Burst Warning Telescope (BAT) and the Swift X-ray Telescope, which detect bursts and examine the X. – ray of reflection. They combined this with additional afterglow studies done with the Lowell Discovery Telescope (LDT), which found that 43 of the short GRBs were not associated with any known galaxies and occurred in the comparatively empty space between galaxies. As O’Connor explained in a University of Maryland news release: “Many small GRBs are found in bright galaxies relatively close to us, but some of them seem to have no corresponding galactic home. By pinpointing where small GRBs come from, we’ve been able to comb through reams of data from observatories like the Gemini twin telescopes to find the faint glow of galaxies that were simply too far away to recognize before. These findings could also have implications for our understanding of the early Universe. In recent years, astronomers have found evidence that precious metals such as gold and platinum may have come from neutron star mergers that occurred billions of years ago. If these events were more common in the past, it could mean that the Universe was seeded with precious metals earlier than expected. Meanwhile, the energetic nature of this event makes it a once-in-a-lifetime opportunity for astronomers. As O’Conner explained: “Extremely long GRB 221009A is the brightest GRB ever recorded, and its afterglow breaks all records at all wavelengths. Because this burst is so bright and also nearby, we believe this is a once-in-a-century opportunity to tackle some of the most fundamental questions about these bursts, from the formation of black holes to testing models of dark matter.” Artist’s impression of the collision of two neutron stars, known as the ‘kilonova’ event. Credits: Elizabeth Wheatley (STScI) Because of its relative proximity to Earth, this event is also a unique opportunity to study the origin of elements heavier than iron (which form inside stars) and whether they come from neutron star mergers only or from collapsing stars as well . Last but not least, this event also led to disturbances in the Earth’s ionosphere that affected long-wave radio emissions and produced very high-energy photons (18 tera-electronvolts) detected by China’s Great High High Air Observatory. How these photons survived the 2.4 billion year journey to Earth is a mystery. Therefore, this data could reveal new insight into how the laws of physics behave in extreme conditions and allow astrophysics to predict the impact future GRBs could have on Earth. The Gemini International Observatory consists of the Gemini North Telescope in Hawaii and the Gemini South Telescope in Chile, which are operated by the National Optical Infrared Astronomy Research Laboratory (NOIRLab) – part of the National Science Foundation (NSF). Papers describing the two teams’ findings recently appeared in Monthly Notices of the Royal Astronomical Society and The Astrophysical Journal. Further reading: NOIRLab, UMD, AJL, MNRAS

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