GRB 221009A

GRB 221009A also known as Swift J1913.1+1946 was an unusually bright and long-lasting gamma-ray burst (GRB) jointly discovered by the Neil Gehrels Swift Observatory and the Fermi Gamma-ray Space Telescope on October 9, 2022. The gamma-ray burst lasted for more than ten hours following detection,[1][2] and could briefly be observed by amateur astronomers.[3] This is also one of the closest gamma-ray bursts and is among the most energetic and luminous bursts.[4] A once-in-10,000-year event,[5][6] its high-intensity emissions span 15 orders of magnitude of the electromagnetic spectrum from radio to gamma-rays and consequently offers a rare opportunity for researchers to study it and events like it in detail.[7][8] Radio signals will likely linger for years to come.[8] GRB 221009A came from the constellation of Sagitta and occurred an estimated 1.9 billion years ago,[7] and is currently at a distance of 2.4 billion light-years away from Earth.[9]

GRB 221009A

Ten-hour timelapse of GRB 221009A, as seen by the Fermi Gamma-ray Space Telescope
Duration	10 hours
Constellation	Sagitta
Right ascension	19h 13m 03.48s
Declination	+19° 46′ 24.6″
Distance	2.4 billion light years
Redshift	0.151
Other designations	Swift J1913.1+1946
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The burst oversaturated the Fermi Gamma-ray Space Telescope,[10] which captured photons whose energies exceeded 100 GeV.[11] The Large High Altitude Air Shower Observatory (LHAASO) in China saw 5,000 high-energy photons. (For comparison, in the entire history of the study of gamma-ray bursts, astronomers have detected only hundreds of these.) Some photons even carried a record 18 TeV of energy,[12][3] which is more than can be produced at the Large Hadron Collider (LHC) at the European Center for Nuclear Research (CERN).[9] Russia's Carpet-2 facility at the Baksan Neutrino Observatory may have recorded a single 251-TeV photon from this burst.[10] By comparing data collected by different observatories, scientists conclude that this event was 50 to 70 times brighter than the previous record holder.[13][5] It could help physicists study how matter interacts at relativistic speeds,[7] and potentially physics beyond the Standard Model.[10]

GRB 221009A could be caused by a dying massive star undergoing a supernova,[3] or the birth of a black hole.[11] Some physicists speculate that such exceptionally high-energy photons could come from new physics involving dark matter,[10] axions or decaying sterile neutrinos.[14] However, there is no conclusive evidence this gamma-ray burst was caused by a supernova,[15][16][17] nor have any neutrinos from this event been detected.[18] Lightning detectors in India and Germany picked up signs of Earth's ionosphere being perturbed for several hours by the burst, though only mildly,[4][10][19] and an enormous influx of electrically charged particles was detected.[20] Some astronomers referred to the burst as the "brightest of all time" or "BOAT",[10][21] a claim justified by the record of known gamma-ray bursts.[6] The afterglow at X-ray energies was hundreds of times brighter than seen before.[22] GRB-221009A is only the seventh gamma-ray burst with X-ray rings.[5] 20 such rings have been identified.[23]

GRB 221009A was subsequently observed by the Neutron Star Interior Composition Explorer (NICER),[7] the Monitor of All-sky X-ray Image (MAXI), the Imaging X-ray Polarimetry Explorer (IXPE),[24][25][26] the International Gamma-ray Astrophysics Laboratory (INTEGRAL), the XMM-Newton space telescope,[27] and many others.[9][13]