![]() The transient nature of the bursts made them difficult to study, but since the late 1990’s astronomers have been able to detect also their less energetic afterglow, from X-rays to optical light, to the infrared, helping to establish a theory of their origin. First thought to originate from nearby sources within our own galaxy, more sensitive space observatories revealed, in the 1990’s, that they must come from far outside the Milky Way, distributed over the whole Universe. Gamma-ray bursts were first discovered in 1967 by the Vela satellite, built to monitor the sky for possible tests of nuclear weapons, which would be a violation of the 1963 Nuclear Test Ban Treaty. Moreover, with a secure distance the team was also able to calculate the total amount of energy released from the burst. ![]() Although the host galaxy of the burst turned out to lie more than two billion lightyears away, this actually makes it one of the most nearby bursts. Using the X-shooter spectrograph mounted at the VLT, the resulting spectrum allowed Malesani and his team to measure the exact distance to GRB 221009A. This led Daniele Bjørn Malesani, astronomer at Radboud University in the Netherlands and affiliated scientist at the Cosmic Dawn Center, to point the Very Large Telescope (VLT) in Chile toward the direction of GRB 221009A. On 9 October 2022, ESA’s INTEGRAL, NASA’s Swift and Fermi satellites, and other space observatories detected the gamma-ray burst which was, accordingly, named GRB 221009A. This allows astronomers to follow up the detections with Earth-based telescopes, to look for a less energetic “afterglow” that often follows the gamma rays. To detect them, scientists, therefore, use space-based gamma-ray telescopes that, when triggered, send automatic instant messages to Earth. Not only are they transient and occur at random locations in the sky gamma rays are also mostly absorbed by our atmosphere impeding their detection from Earth. The explosions are believed to be caused by the collapse of massive stars, the collision of neutron stars, or the merging of a neutron star and a black hole.Īlthough we have known about their existence for 60 years, there is still much to learn about these fascinating events. Short-lived flashes of gamma-rays that typically last from a tenth of a second to less than an hour, gamma-ray bursts may for a brief period of time outshine entire galaxies. Gamma-ray bursts are the most energetic and luminous events known to occur in the Universe. A team of scientists led by astronomers at the Cosmic Dawn Center measured the exact distance to the burst, allowing them to calculate the total energy released: During its duration of just five minutes, it released 1,000 times more energy than our Sun has emitted throughout its 4.5 billion year life, making the burst the single most energetic ever detected. A particularly bright burst, GRB 221009, was recently detected by several space telescopes. ![]() Gamma-ray bursts are the most energetic explosions in the Universe, marking the end of a star’s life. Observed with the VLT and James Webb Space Telescope, this event left scientists puzzled about gamma-ray bursts’ nature and the possible absence of an accompanying supernova. GRB 221009A, the most energetic gamma-ray burst ever recorded, released 1,000 times more energy than the Sun’s lifetime output. ![]() Artist’s illustration of a gamma-ray burst resulting from a collapsing star, ejecting particles and radiation in a narrow jet.
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