Neutron
A neutron star is the collapsed core of a massive supergiant star, which had a total mass of between 10 and 25 solar masses (M☉), possibly more if the star was especially metal-rich.[1] Except for black holes, neutron stars are the smallest and densest known class of stellar objects.[2] Neutron stars have a radius on the order of 10 kilometers (6 mi) and a mass of about 1.4 M☉.[3] They result from the supernova explosion of a massive star, combined with gravitational collapse, that compresses the core past white dwarf star density to that of atomic nuclei.
Magnetar
the first-observed SGR megaflare.
Artist's impression of a gamma-ray burst and supernova powered by a magnetar[22]
On February 21, 2008, it was announced that NASA and researchers at McGill University had discovered a neutron star with the properties of a radio pulsar which emitted some magnetically powered bursts, like a magnetar. This suggests that magnetars are not merely a rare type of pulsar but may be a (possibly reversible) phase in the lives of some pulsars.[23] On September 24, 2008, ESO announced what it ascertained was the first optically active magnetar-candidate yet discovered, using ESO's Very Large Telescope. The newly discovered object was designated SWIFT J195509+261406.[24] On September 1, 2014, ESA released news of a magnetar close to supernova remnant Kesteven 79. Astronomers from Europe and China discovered this magnetar, named 3XMM J185246.6+003317, in 2013 by looking at images that had been taken in 2008 and 2009.[25] In 2013, a magnetar PSR J1745−2900 was discovered, which orbits the black hole in the Sagittarius A* system. This object provides a valuable tool for studying the ionized interstellar medium toward the Galactic Center. In 2018, the temporary result of the merger of two neutron stars was determined to be a hypermassive magnetar, which shortly collapsed into a black hole
https://wiki.openstack.org/wiki/Neutron
In April 2020, a possible link between fast radio bursts (FRBs) and magnetars was suggested, based on observations of SGR 1935+2154, a likely magnetar located in the Milky Way galaxy
Astronomy
Astronomy is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, galaxies, meteoroids, asteroids, and comets. Relevant phenomena include supernova explosions, gamma ray bursts, quasars, blazars, pulsars, and cosmic microwave background radiation. More generally, astronomy studies everything that originates beyond Earth's atmosphere. Cosmology is a branch of astronomy that studies the universe as a whole.
The Paranal Observatory of European Southern Observatory shooting a laser guide star to the Galactic Center
Astronomy is one of the oldest natural sciences. The early civilizations in recorded history made methodical observations of the night sky. These include the Egyptians, Babylonians, Greeks, Indians, Chinese, Maya, and many ancient indigenous peoples of the Americas. In the past, astronomy included disciplines as diverse as astrometry, celestial navigation, observational astronomy, and the making of calendars.
Professional astronomy is split into observational and theoretical branches. Observational astronomy is focused on acquiring data from observations of astronomical objects. This data is then analyzed using basic principles of physics. Theoretical astronomy is oriented toward the development of computer or analytical models to describe astronomical objects and phenomena. These two fields complement each other. Theoretical astronomy seeks to explain observational results and observations are used to confirm theoretical results.
Astronomy is one of the few sciences in which amateurs play an active role. This is especially true for the discovery and observation of transient events. Amateur astronomers have helped with many important discoveries, such as finding new comets.
explain such observed phenomena as quasars, pulsars, blazars, and radio galaxies. Physical cosmology made huge advances during the 20th century. In the early 1900s the model of the Big Bang theory was formulated, heavily evidenced by cosmic microwave background radiation, Hubble's law, and the cosmological abundances of elements. Space telescopes have enabled measurements in parts of the electromagnetic spectrum normally blocked or blurred by the atmosphere.[43] In February 2016, it was revealed that the LIGO project had detected evidence of gravitational waves in the previous September.[44][45]
In radio astronomy
In radio astronomy, a fast radio burst (FRB) is a transient radio pulse of length ranging from a fraction of a millisecond, for an ultra-fast radio burst,[2][3] to 3 seconds,[4] caused by some high-energy astrophysical process not yet understood. Astronomers estimate the average FRB releases as much energy in a millisecond as the Sun puts out in three days.[5] While extremely energetic at their source, the strength of the signal reaching Earth has been described as 1,000 times less than from a mobile phone on the Moon.[6]
Lorimer Burst – Observation of the first detected fast radio burst as described by Lorimer in 2006.[1]
The first FRB was discovered by Duncan Lorimer and his student David Narkevic in 2007 when they were looking through archival pulsar survey data, and it is therefore commonly referred to as the Lorimer Burst.[7][8] Many FRBs have since been recorded, including several that have been detected to repeat in seemingly irregular ways.[9][10][11][12][13] Only one FRB has been detected to repeat in a regular way: FRB 180916 seems to pulse every 16.35 days.[14][15]
Most FRBs are extragalactic, but the first Milky Way FRB was detected by the CHIME radio telescope in April 2020.[16] In June 2021, astronomers reported over 500 FRBs from outer space detected.[17]
When the FRBs are polarized, it indicates that they are emitted from a source contained within an extremely powerful magnetic field.[18] The exact origin and cause of the FRBs is still the subject of investigation; proposals for their origin range from a rapidly rotating neutron star and a black hole, to extraterrestrial intelligence.[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".[21][22][23] A neutron star has been proposed as the origin of an unusual FRB with periodic peaks lasting over 3 seconds reported in 2022.[24]
The discovery in 2012 of the first repeating source, FRB 121102, and its localization and characterization in 2017, has improved the understanding of the source class. FRB 121102 is identified with a galaxy at a distance of approximately three billion light-years and is embedded in an extreme environment.[25][18] The first host galaxy identified for a non-repeating burst, FRB 180924, was identified in 2019 and is a much larger and more ordinary galaxy, nearly the size of the Milky Way. In August 2019, astronomers reported the detection of eight more repeating FRB signals.[26][27] In January 2020, astronomers reported the precise location of a second repeating burst, FRB 180916.[28][29] One FRB seems to have been in the same location as a known gamma-ray burst.[30][16]
On 28 April 2020, a pair of millisecond-timescale bursts (FRB 200428) consistent with observed fast radio bursts, with a fluence of >1.5 million Jy ms, was detected from the same area of sky as the magnetar SGR 1935+2154.[31][32] Although it was thousands of times less intrinsically bright than previously observed fast radio bursts, its comparative proximity rendered it the most powerful fast radio burst yet observed, reaching a peak flux of either a few thousand or several hundred thousand janskys, comparable to the brightness of the radio sources Cassiopeia A and Cygnus A at the same frequencies. This established magnetars as, at least, one ultimate source of fast radio bursts,[33][34][35] although the exact cause remains unknown.[36][37][38] Further studies support the notion that magnetars may be closely associated with FRBs.[39][40] On 13 October 2021, astronomers reported the detection of hundreds of FRBs from a single system.[41][42]
Because of the isolated nature of the observed phenomenon, the nature of the source remains speculative. As of 2022, there is no generally accepted single explanation, although a magnetar has been identified as a possible source. The sources are thought to be a few hundred kilometers or less in size, as the bursts last for only a few milliseconds. Causation is limited by the speed of light, about 300 km per millisecond, so if the sources were larger than about 1000 km, a complex synchronization mechanism would be required for the bursts to be so short. If the bursts come from cosmological distances, their sources must be very energetic.[6]
One possible explanation would be a collision between very dense objects like merging black holes or neutron stars.[52][53][54] It has been suggested that there is a connection to gamma-ray bursts.[55][56] Some have speculated that these signals might be artificial in origin, that they may be signs of extraterrestrial intelligence,[57][58][59] demonstrating veritable technosignatures.[60] 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").[61] In 2007, just after the publication of the e-print with the first discovery, it was proposed that fast radio bursts could be related to hyperflares of magnetars.[62][63] In 2015 three studies supported the magnetar hypothesis.[51][64][65][66] The identification of first FRB from the Milky Way, which originated from the magnetar SGR 1935+2154, indicates that magnetars may be one source of FRB.[34]
Especially energetic supernovae could be the source of these bursts.[67] Blitzars were proposed in 2013 as an explanation.[6] In 2014 it was suggested that following dark matter-induced collapse of pulsars,[68] the resulting expulsion of the pulsar magnetospheres could be the source of fast radio bursts.[69] In 2015 it was suggested that FRBs are caused by explosive decays of axion miniclusters.[70] Another exotic possible source are cosmic strings that produced these bursts as they interacted with the plasma that permeated the early Universe.[67] 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.[71][72] 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.[54][73] 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 magnet
osphere, releasing trapped energy to power the FRBs.[74]