Fast radio burst
[19][20] In 2020, astronomers reported narrowing down a source of fast radio bursts, which may now plausibly include "compact-object mergers and magnetars arising from normal core collapse supernovae".
[41][42] In 2024, an international team led by astrophysicists of INAF, using detections from VLA, NOEMA interferometer, and Gran Telescopio Canarias has conducted a research campaign about FRB20201124A, one of the two known persistent FRB, located about 1.3 billion light-years away.
Based on the outcomes of the study, authors deem to confirm the origin of FRBs in a binary system at high accretion rate, that would blow a plasma bubble, responsible for the persistent radio emission.
On 19 January 2015, astronomers at Australia's national science agency (CSIRO) reported that a fast radio burst had been observed for the first time live, by the Parkes Observatory.
Unlike many radio sources, the signal from a burst is detected in a short period of time with enough strength to stand out from the noise floor.
This limit can be determined from the fact that closer sources would have a curved wave front that could be detected by the multiple antennas of the interferometer.
[51] Fast radio bursts have pulse dispersion measurements > 100 pc cm−3[52], much larger than expected for a source inside the Milky Way galaxy[53] and consistent with propagation through an ionized plasma.
[64] Analogously, when the first pulsar was discovered, it was thought that the fast, regular pulses could possibly originate from a distant civilization, and the source nicknamed "LGM-1" (for "little green men").
[74] Another exotic possible source are cosmic strings that produced these bursts as they interacted with the plasma that permeated the early Universe.
[71] In 2016 the collapse of the magnetospheres of Kerr–Newman black holes were proposed to explain the origin of the FRBs' "afterglow" and the weak gamma-ray transient 0.4 s after GW 150914.
[75][76] It has also been proposed that if fast radio bursts originate in black hole explosions, FRBs would be the first detection of quantum gravity effects.
[58][77] In early 2017, it was proposed that the strong magnetic field near a supermassive black hole could destabilize the current sheets within a pulsar's magnetosphere, releasing trapped energy to power the FRBs.
[79] A coherent emission phenomenon known as superradiance, which involves large-scale entangled quantum mechanical states possibly arising in environments such as active galactic nuclei, has been proposed to explain these and other associated observations with FRBs (e.g. high event rate, repeatability, variable intensity profiles).
[58] Analysis of the survey data found a 30-jansky dispersed burst which occurred on 24 July 2001,[49] less than 5 milliseconds in duration, located 3° from the Small Magellanic Cloud.
The reported burst properties argue against a physical association with the Milky Way galaxy or the Small Magellanic Cloud.
[84] The discoverers argue that current models for the free electron content in the Universe imply that the burst is less than 1 gigaparsec distant.
The fact that no further bursts were seen in 90 hours of additional observations implies that it was a singular event such as a supernova or merger of relativistic objects.
[87] Victoria Kaspi of McGill University estimated that as many as 10,000 fast radio bursts may occur per day over the entire sky.
[95] As of April 2018, FRB 121102 is thought to be co-located in a dwarf galaxy about three billion light-years from Earth with a low-luminosity active galactic nucleus, or a previously unknown type of extragalactic source, or a young neutron star energising a supernova remnant.
[96][97][25][98][99][100] On 26 August 2017, astronomers using data from the Green Bank Telescope detected 15 additional repeating FRBs coming from FRB 121102 at 5 to 8 GHz.
The researchers also noted that FRB 121102 is presently in a "heightened activity state, and follow-on observations are encouraged, particularly at higher radio frequencies".
[103] Since it is a repeating FRB source, it suggests that it does not come from some one-time cataclysmic event; so one hypothesis, first advanced in January 2018, proposes that these particular repeating bursts may come from a dense stellar core called a neutron star near an extremely powerful magnetic field, such as one near a massive black hole,[103] or one embedded in a nebula.
[123] It was also noted that what was thought to be an afterglow did not fade away as would be expected, supporting the interpretation that it originated in the variable AGN and was not associated with the fast radio burst.
[131][132] In October 2018, astronomers reported 19 more new non-repeating FRB bursts detected by the Australian Square Kilometre Array Pathfinder (ASKAP).
[26][27] On 29 December 2019, Australian astronomers from the Molonglo Observatory Synthesis Telescope (MOST), using the UTMOST fast radio burst equipment, reported the detection of FRB 191223 in the Octans constellation (RA = 20:34:14.14, DEC = -75:08:54.19).
[161][163] In February & March 2022, astronomers reported that a globular cluster of M81, a grand design spiral galaxy about 12 million light-years away, may be the source of FRB 20200120E, a repeating fast radio burst.
[164][165][166] Astronomers reported the discovery of FRB 20200317A (RA 16h22m45s, DEC p+56d44m50s) with FAST (Five-hundred-meter Aperture Spherical radio Telescope) in archival data on 22 September 2023.
[167] On 28 April 2020, astronomers at the Canadian Hydrogen Intensity Mapping Experiment (CHIME), reported the detection of a bright radio burst from the direction of the Galactic magnetar SGR 1935+2154 about 30,000 light years away in the Vulpecula constellation.
[209] On 13 November 2022, further burst activity of FRB 20220912A was reported by the Tianlai Dish Pathfinder Array in Xinjiang, China[210] and, on 5 December 2022, from several other observatories.
[220] Observations of FRB 20230905 in the X-ray and UV range by the Neil Gehrels Swift Observatory was reported as bright and non-repeating on 7 September 2023.
