Fast radio bursts (FRBs) are intense bursts of extragalactic radio waves lasting no more than a few milliseconds. They were first discovered in 2007 by Duncan Lorimer and his student David Narkiewicz while studying data from the Pulsar Survey. To date, between 50 and 60 FRBs have been detected, although according to Victoria Caspi, an astrophysicist at McGill University, there may be as many as 10,000 per day. Recently, the second-ever repeating fast radio burst was detected, providing another clue to understanding the mystery of the universe.
In summer 2018 years Canada's new CHIME telescope has detected 13 fast radio bursts (FRBs) in just three weeks. These are the second repeating FRB bursts, the first of which was discovered in 2012 by the Arecibo radio telescope in Puerto Rico.
The first repeating fast radio burst (named FRB 121102) was discovered by a group of students led by then-graduate student Paul Scholz. After analyzing all the data, they discovered that the initial signal was followed by 10 more bursts. The scientists believe the source of these bursts may be a dwarf galaxy located 2.5 billion light-years from Earth.
The second repeating fast radio burst (FRB 180725A) first appeared on August 14, 2018, and has since recurred at the same location in the sky at least five times. The CHIME team published their findings on January 9 of this year in two papers in the journal Nature , and presented them at a conference of the American Astronomical Society.
Located at the Dominion Radio Astrophysical Observatory in British Columbia, Canada, the CHIME telescope is equipped with four highly sensitive radio receivers measuring 100 by 20 meters. Their purpose is to measure the acceleration of radio waves in the universe, study the Milky Way, track pulsars, and detect fast radio bursts (FRBs).
The Canadian Hydrogen Intensity Mapping Experiment (CHIME) was inaugurated on September 7, 2017, during a maiden launch ceremony (this marked the first time the telescope was used to obtain astronomical images). The telescope is specifically designed to receive signals in the 400 to 800 MHz range with high sensitivity. The received data is processed at a rate of 13 terabits per second. It is then digitized and processed to create sky maps.
CHIME scans space for fast radio bursts (FRBs) all day long, using 1,024 points or beams. Each beam is processed at 16,000 different frequencies 1,000 times per second, which means 130 billion bits of data are analyzed in real time. After the first processing stage, which utilizes 2,500 processors and 32,000 gigabytes of RAM, the second stage determines the location and details of a potential FRB. When an FRB occurs, the CHIME team and the astrophysics community are immediately notified.
Initially, there was skepticism about CHIME's ability to detect fast radio bursts at such low frequencies, as previous models operated at frequencies close to 1400 MHz. However, scientists now believe that fast radio bursts with frequencies below 400 MHz also exist.
Some of the 13 signals in the repeating fast radio burst at the lower end of the spectrum were so bright that the CHIME team believes that bursts below 400 MHz may also exist. They also believe that many more repeating fast radio bursts below 700 MHz may have occurred in the past but were not recognized as such.
Following FRB 180725A, the CHIME instrument detected several more fast radio bursts (FRBs) around 400 MHz, both day and night, that do not correlate with any known terrestrial source. If these signals are confirmed, it will provide a better understanding of the frequency limits within which FRBs occur, as well as the causes of these bursts.
No one yet knows why or how fast radio bursts (FRBs) are emitted. Proposed hypotheses include collisions of black holes or neutron stars, high-energy supernovae, blitzars, and the collapse of pulsars caused by dark matter.
Since the discovery of fast radio bursts (FRBs), scientists have been trying to determine the nature of their sources. Because the bursts are so short, they are believed to have sources several hundred kilometers or smaller in size. They are also believed to be extremely energetic, generating as much energy in a single burst as the Sun would produce in 80 years.
One suggestion for their origin is that they may originate from other advanced extraterrestrial life forms, although similar theories were put forward regarding the regular pulses generated by pulsars prior to their discovery. Other theories include the explosive decay of mini-clusters of axions, cosmic strings, and the collapse of the magnetospheres of Kerr-Newman black holes. It has been suggested that if fast radio bursts do indeed originate from black hole explosions, they are the first signs of quantum gravity.
In the case of recurring fast radio bursts, some hypotheses suggest multiple origins due to differences in the intensity of each signal. One theory posits that large-scale entangled quantum mechanical states exist in the environment of active galactic nuclei, which can lead to increased emission—a phenomenon known as "superradiance.".
Thirteen fast radio bursts (FRBs) showed signs of "scattering," a phenomenon that occurs when radio waves pass through the source's environment. Depending on the nature of the wave scattering, scientists believe it's possible to determine the nature of the surrounding environment.
According to CHIME team member Tom Landecker, "low-frequency waves can escape their environment and are not scattered enough to be detectable by the time they reach Earth." This degree of scattering indicates that the sources are powerful astrophysical objects located in places such as supernova remnants or near the galaxy's central black hole, notes Cherry Ng, an astronomer at the University of Toronto. Detecting more fast radio bursts in the future and analyzing the data will provide scientists with more information to help them identify the sources and their nature.
[Sources: CHIME, Nature, Wikipedia]