Fast Radio Bursts (FRBs)

 

 

In radio astronomy, a fast radio burst (FRB), also known as a Lorimer Burst, is a transient radio pulse that lasts about a fraction of a millisecond.  It is one of the oddest puzzles of modern astronomy.  FRBs are rare, extremely bright flashed of light with radio wavelengths.  They put out more energy in one millisecond than the Sun puts out in 3 days.  FRBs are named by the date that the signal was recorded as “FRB YYMMDD”.  In most cases, the high frequency signal shows up first, followed by the low frequency signal.  This is known as dispersion.  It was estimated that 10,000 bursts a day was occurring and that 1,000 FRBs arrive at Earth each day.

Astronomers were unsure how FRBs were generated.  Theories included supernova activity, colliding neutron stars, or neutron stars falling into black holes, or comets and asteroids slamming into neutron stars, or primordial black holes exploding.  There was even a theory that they were lighthouse beams created by aliens.

In 2007 Duncan Lorimer of West Virginia University and his student, David Narkevic, detected the first FRB (FRB 010724).  They were using the Parkes 64-meter radio dish in Australia and were looking through archival pulsar (rapidly rotating neutron stars) survey data when they discovered the first FRB.  The archived data was first detected by the Parkes Observatory on July 24, 2001.  The FRB (5 millisecond burst) was located near the Small Magellanic Cloud.

In 2012, FRB 121102 was discovered as one of three repeating sources.  It was identified with a galaxy 3 billion light-years away.  The FRB was located in the direction of the constellation Auriga using the Arecibo radio telescope (300 meter dish) in Puerto Rico.  Arecibo later detected 10 more FRBs.

In 2013, four more FRBS were detected (FRB 110220, FRB 110627, FB 110703, and FRB 120127).

On January 19, 2015, the first FRB was observed for the first time live, by the Parkes Observatory.

In 2015, FRB 110523 was discovered in archival data collected in 2011 from the Green Bank Telescope in Green Bank, West Virginia.   It was the first FRB for which liner polarization was detected.

In 2015, three studies supported the hypothesis that FRBs were related to hyperflares of magnetars (ultra magnetized neutron stars).

In 2016, the Very Large Array (VLA) in New Mexico started hunting FRBs.

In 2017, the Molonglo Observatory Synthesis Telescope (UTMOST) near Canberra, Australia, detected 3 FRBs.

In September 2017, the Canadian Hydrogen Intensity Mapping Experiment (CHIME) radio telescope came online in British Columbia.  It was used to detect hundreds of FRBs.  It detected 13 FRBs will still being tested.

In 2018, three FRBs were reported by the Parkes Observatory.  One (FRB 180309) had the highest signal to noise ration yet seen at 411.

In October 2018, 19 FRBs were detected by the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope.

On January 9, 2019, a second repeating FRB (FRB 180814) was discovered by CHIME.

In January 2019, FRB 180924 was identified as a non-repeating FRB from a galaxy nearly the size of the Milky Way.

In June 2019, Russian astronomers discovered 9 FRBs.  FRB 151125 was the third repeating one ever detected. 

In August 2019, eight more repeating FRBs were detected by CHIME. 

In January 2020, a repeating FRB 180916 was detected with precise location in the medium-sized spiral galaxy SDSS J015800.28+654253.0 about 500 million light-years away.  It was the closest FRB discovered to date and the first FRB to have regular periodicity.

In March 2020, CHIME found 10 more repeating FRBs.

The FRB origins seems outside our Milky Way Galaxy.  They seem to come from regions with strong magnetic fields.  The discovery was made by Dongzi Li, an astrophysicist at the University of Toronto, using the Canadian Hydrogen Intensity Mapping Experiment (CHIME) radio telescope in British Columbia.  [source: “Periodic activity from a fast radio burst source,” arXiv.org, Jan 28, 2020]

On April 28, 2020, a pair of millisecond bursts came from FRB 200428, in the same area of the sky as the magnetar neutron star SGR 1935+2154 inside the Milky Way galaxy.  It was the most powerful FRB yet observed and the first detected in the Milky Way galaxy.  The FRB was detected by CHIME.  The neutron star is about 30,000 light-years away in the constellation Vulpecula.  SGR 1935 had 200 X-ray bursts in 20 minutes the day before.  The next day it emitted another flare.  Newly ejected electrons and particles collided with debris from the previous flare which may have produced the FRB.

In April 2021, astronomers detected a new, nearby, repeating FRB, originating from a spot near the M81 spiral galaxy, 12 million light-years away.  The FRB repeated its burst in January 2020, July 2020, and November 2020.  This may be the closest FRB found so far.  [source: earthsky.org, April 8, 2021]