Astronomers Detect ‘Heartbeat’ Radio Signal

A peculiar and persistent radio signal from a distant galaxy has been discovered by astronomers at MIT and universities in Canada and the United States. This signal appears to be flashing with a startling degree of regularity. The signal is categorised as a fast radio burst (FRB), which is a brief but extremely powerful burst of radio waves with an unknown astrophysical origin. However, compared to the typical FRB, this novel signal lasts up to three seconds, or 1,000 times longer. The scientists discovered radio wave bursts within this window that have a distinct periodic rhythm and reoccur every 0.2 seconds, resembling a heartbeat.

The signal, FRB 20191221A, was identified by the researchers as the longest-lasting FRB to date and having the most distinct periodic pattern. Several billion light-years away from Earth, in a far-off galaxy, is where the signal’s source is located. Astronomers believe the signal may have come from either a radio pulsar or a magnetar, two different forms of neutron stars that are incredibly compact and fast spinning collapsed cores of big stars. However, the precise nature of that source is yet unknown.

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According to Daniele Michilli, a postdoc at MIT’s Kavli Institute for Astrophysics and Space Research, “There are not many entities in the cosmos that emit strictly periodic signals.” “Radio pulsars and magnetars, which revolve and emit a beamed output akin to a lighthouse, are examples that we are aware of in our own galaxy. Additionally, we believe that this new signal might be an enhanced magnetar or pulsar.

In order to use this source as an astrophysical clock, the team wants to find more periodic signals from it. For instance, the velocity of the universe’s expansion might be gauged by the frequency of the bursts and how they alter as the source travels away from Earth.

Members of the CHIME/FRB Collaboration, including Calvin Leung, Juan Mena-Parra, Kaitlyn Shin, and Kiyoshi Masui at MIT, along with Michilli, who led the discovery first as a researcher at McGill University and then as a postdoc at MIT, are the authors of the discovery, which was published today in the journal Nature.

Boing, boing, boing

Since the first FRB was found in 2007, hundreds of comparable radio flashes have been found throughout the cosmos. The most recent discovery was made by the Canadian Hydrogen Intensity Mapping Experiment, or CHIME, an interferometric radio telescope made up of four sizable parabolic reflectors at the Dominion Radio Astrophysical Observatory in British Columbia, Canada.

CHIME, which is built to detect radio waves released by hydrogen in the very early phases of the universe, continuously scans the sky as the Earth spins. The telescope is also capable of picking up fast radio bursts, and since it started scanning the sky in 2018, CHIME has picked up hundreds of FRBs coming from various locations.

The vast majority of FRBs that have been seen so far are one-offs, which are ultrabright radio wave bursts that last just a few milliseconds before disappearing. Recently, scientists made the first observation of a periodic FRB that seemed to generate a predictable pattern of radio waves. A four-day span of erratic bursts that then repeated every 16 days made up this signal. Despite the fact that the signal of the actual radio bursts was random rather than periodic, this 16-day cycle showed a periodic pattern of activity. On December 21, 2019, CHIME detected a probable FRB signal, which quickly caught Michilli’s eye as she was scanning the incoming data.

dazzling flashes

Michilli and his colleagues discovered parallels between the pattern of radio bursts from FRB 20191221A and those coming from radio pulsars and magnetars in our own galaxy. While magnetars produce a comparable emission because of their strong magnetic fields, radio pulsars emit beams of radio waves that appear to pulse as the star rotates.

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