Credit: NASA's Goddard Space Flight Center
A Bright, Weird Burst
Gamma-ray bursts (GRBs) are sudden explosions of extreme, high-energy radiation in deep space, produced by cataclysmic events, like the collision of neutron stars or the explosive collapse of very massive, rapidly rotating stars. The brightest GRB was observed on October 9, 2022 by the Gamma Ray Burst Monitor (a set of detectors on the Fermi Gamma-Ray Space Telescope) and other gamma-ray satellite observatories. This event is now famous, dubbed the "BOAT" (for "brightest of all time") by high energy astrophysicists. This gamma-ray outburst is believed to have arisen from the formation of a black hole at the center of an extremely massive star when the star's core collapsed after it exhausted its nuclear fuel. When this happens, the black hole swallows such large portions of the star at such a rapid pace that not all the material can be eaten by the black hole, and some gets ejected in a powerful, narrow beam of charged particles, which shoots through the star and blows the star apart (as in the illustration above, which shows the particle beam blasting through the surface of the dead star). This prompt burst of radiation, lasting for a few seconds, is followed by a longer afterglow produced as the exploded remnants of the star collide with surrounding interstellar gas. Astronomers are now studying the X-rays from this afterglow with the NuSTAR high-energy X-ray space telescope, and other orbiting X-ray telescopes, in hopes of unraveling the secrets of the GRB's unsurpassed brightness. These observations show that, for the BOAT, the drop in X-ray emission of the afterglow is not as rapid as predicted by models of an explosion into a uniform medium. This may indicate that the jet had unusual difficulty passing through the star, or that the environment around the star that exploded was very clumpy due to prior eruptions of the star in the decades or centuries before the burst.
Published: August 21, 2023
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Page Author: Dr. Michael F. Corcoran
Last modified Tuesday, 27-Feb-2024 10:15:16 EST