astronomyblog: Fast radio burst (FRB) In…

astronomyblog:

Fast radio burst (FRB)

In radio astronomy, a fast radio burst (FRB) is a high-energy astrophysical phenomenon of unknown origin manifested as a transient radio pulse lasting a few milliseconds on average.

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 Lorimer Burst. Many FRBs have since been found, including a repeating FRB. Although the exact origin and cause is uncertain, they are almost definitely extragalactic, with the nearest roughly 1.6 billion light years away, and the furthest 17 billion light years away (comoving).

When the FRBs are polarized, it indicates that they are emitted from a source contained within an extremely powerful magnetic field. The origin of the FRBs has yet to be determined; proposals for its origin range from a rapidly rotating neutron star and a black hole to extraterrestrial intelligence.

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Neutron star

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Black Holes

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Sign of extraterrestrial intelligence?

The localization and characterization of the one known repeating source, FRB 121102, has revolutizoned the understanding of the source class. FRB 121102 is identified with a galaxy at a distance of approximately 3 billion light years, well outside the Milky Way Galaxy, and embedded in an extreme environment.

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Fast radio bursts are named by the date the signal was recorded, as “FRB YYMMDD”. The first fast radio burst to be described, the Lorimer Burst FRB 010724, was identified in 2007 in archived data recorded by the Parkes Observatory on 24 July 2001. Since then, most known FRBs have been found in previously recorded data. 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.

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Parkes radio telescope

Fast radio bursts are bright, unresolved (pointsource-like), broadband (spanning a large range of radio frequencies), millisecond flashes found in parts of the sky outside the Milky Way. 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. 

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The burst usually appears as a single spike of energy without any change in its strength over time. The bursts last for a period of several milliseconds (thousandths of a second). The bursts come from all over the sky, and are not concentrated on the plane of the Milky Way. Known FRB locations are biased by the parts of the sky that the observatories can image.