![]() ![]() Ancient cedar trees in Japan have revealed the secrets of an 8th century gamma ray burst. We plan to keep looking, but it’s possible the entire star collapsed straight into the black hole instead of exploding.” Is GRB 221009A really the biggest gamma ray burst of all time? Freshly-cut cedar logs. “We cannot say conclusively that there is a supernova, which is surprising given the burst’s brightness,” says Andrew Levan from Radboud University in the Netherlands. One piece of the puzzle is missing, however: there is no sign of the supernova that created the black hole, possibly due to dust in the Milky Way blocking its light. It will allow astronomers to study what produces black hole jets, the process of which is not well-understood, but may be driven by the black hole’s magnetic field. “Being so close and so bright, this burst offered us an unprecedented opportunity to gather observations of the afterglow across the electromagnetic spectrum and to test how well our models reflect what’s really happening in GRB jets,” says Kate Alexander from the University of Arizona. Fruchter (STScI), and the GOSH Collaboration A Hubble Space Telescope image showing a number of galaxies thought to host bright gamma-ray bursts. Its light has been travelling for around 1.9 billion years, making it one of the closest ever detected. Observatories around the world look out for these signals as they pass over Earth, but the BOAT was so bright it over-saturated most of them.įortunately, NASA’s Fermi Gamma-ray Space Telescope made out the burst, revealing it was 70 times brighter than any previously observed. These jets emit powerful gamma and X-rays that can cross the Universe. GRBs are thought to be created when a large star’s core collapses to form a black hole, which then quickly ingests the gas surrounding it before blasting the material out at near to light speed. An artist’s impression of a gamma ray burst. The event is called GRB 221009A (ringed in the image above), though it has been nicknamed the BOAT – the brightest of all time. Seen on 9 October 2022, it’s believed such blasts only occur once every 10,000 years. These nuclei are called "cosmic ray clocks".Flash of space radiation that swept across Earth is brightest on recordĪ flash of radiation called a gamma-ray burst (GRB) that swept across Earth last year was the brightest on record, astronomers have recently been able to confirm. As in the carbon-14 dating technique, measurements of these nuclei can be used to determine how long it has been since cosmic ray material was synthesized in the galactic magnetic field before leaking out into the vast void between the galaxies. Included in the cosmic rays are a number of radioactive nuclei whose numbers decrease over time. Some GCRs interact with the interstellar medium and produce The image on the right is the EGRET gamma but studies of the composition of the isotopes in GCRs may indicate the that the seed population for GCRs is neither the interstellar gas nor the shards of giant stars that went supernova. The elemental makeup of GCRs has been studied in detail, and is very similar to the composition of the Earth and solar system. As they travel through the very thin gas of interstellar space, some of the GCRs interact and emit gamma rays, which is how we know that they pass through the Milky Way and other galaxies. GCRs have been accelerated to nearly the speed of light, probably by supernova remnants. They have probably been accelerated within the last few million years, and have traveled many times across the galaxy, trapped by the galactic magnetic field. GCRs are atomic nuclei from which all of the surrounding electrons have been stripped away during their high-speed passage through the galaxy. Galactic cosmic rays (GCRs) come from outside the solar system but generally from within our Milky Way galaxy. ![]()
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