Astronomy: They discovered “heartbeats” billions of light years from Earth

MIT astronomers have detected a strange, persistent radio signal from a distant galaxy, Which seems to blink surprisingly regularly.

The signal is classified as a fast radio burst, or FRB, which is a very strong burst of radio waves of unknown astrophysical origin, usually lasting for a few milliseconds at most. However, this new signal lasts for up to three seconds, about 1,000 times longer than the average FRB. Within this window, the team detected bursts of radio waves that repeat every 0.2 seconds with a distinct periodic pattern, similar to a heartbeat.

The researchers named the signal FRB 20191221A, and it is currently the longest-running FRB, with the clearest periodic pattern detected to date.. The source of the signal is located in a distant galaxy, several billion light years from Earth. What exactly this source may be remains a mystery, though astronomers They suspect that the signal could be emitted by a pulsar or magnetarwhich are types of neutron stars: very dense, rapidly rotating cores of collapsed giant stars.

“There are not many things in the universe that emit strict periodic signals. Examples we know of in our galaxy are radio and magnetic pulsars, which rotate and produce an emission similar to that of a lighthouse. s We think this new signal could be a magnetar or a pulsar on steroids“, It is to explain Danielle Micheli, Postdoctoral fellow at the Kavli Institute for Astrophysics and Space Research at the Massachusetts Institute of Technology. The team hopes to discover more periodic signals from this source, which can then be used as an astrophysical clock. For example, the frequency of eruptions and how they change as the source moves away from Earth can be used to measure the expansion rate of the universe.

This discovery was reported this week in the journal temper nature It is written by members CHIME/FRB collaborated, including MIT co-authors Calvin Leung, Juan Mina-Barra, Kaitlin Shen, and Kiyoshi Masui, along with Micheli.who led the discovery first as a researcher at McGill University and then as a postdoc at the Massachusetts Institute of Technology. Since the first FRB was discovered in 2007, hundreds of similar radio flashes have been detected throughout the universe, most recently by the Canadian Hydrogen Intensity Mapping Experiment, or CHIME, an interferometric radio telescope consisting of four large reflectors. Field of the Astrophysical Observatory in British Columbia, Canada.

CHIME constantly monitors the sky as the Earth rotates and is designed to capture radio waves emitted by hydrogen in the early universe. The telescope is also sensitive to fast radio bursts, and since it began observing the sky in 2018And the CHIME has discovered hundreds of FRBs emanating from different parts of the sky.

The vast majority of FRBs observed so far are single bursts: Ultra-bright bursts of radio waves that last a few milliseconds before fading out.Researchers recently discovered the first periodic FRB that appears to emit a regular pattern of radio waves.. This signal consists of a four-day window of random bursts that then repeat every 16 days. This 16-day cycle indicated a periodic pattern of activity, although the signal from the actual radio bursts was random rather than periodic.

On December 21, 2019, CHIME detected a signal from a possible FRB, Which immediately caught the attention of Mitchell, who was scanning the incoming data. “It was unusual,” he recalls.. “It wasn’t very long, it lasted about three seconds, but there were periodic spikes that were remarkably accurate, emitting every millisecond, boom, boom, boom, like a heartbeat. This is the first time that the same signal has been periodic.” “

By analyzing the radio burst pattern from FRB 20191221A, Mitchell and colleagues found similarities with emissions from radio and magnetic pulsars in our galaxy. Radio pulsars are neutron stars that emit beams of radio waves.which appear to pulsate with the star’s rotation, while magnetars produce a similar emission due to their intense magnetic fields.

The main difference between the new signal and radio emission from galactic pulsars and magnetospheres is that FRB 20191221A It appears to be a million times brighter. The bright flashes may originate from a distant radio pulsar or magnetar that is usually faint as it rotates and, for some unknown reason, set off a series of bright explosions, in a rare three-second window that CHIME was fortunately able to detect, Micheli says. pick up.

“CHIME has now discovered many different FRBs with different characteristics,” says Michilli. “We have seen some live inside very turbulent clouds, while others appear to be in clean environments. From the characteristics of this new signal, we can say that around this source there is a cloud of plasma, which should be very turbulent.”

Astronomers hope to catch additional bursts of periodic FRB 20191221A, which may help Refine your understanding of their origin and neutron stars in general. “This discovery raises the question of what could be causing this extreme signal that we haven’t seen before, and how we can use this signal to study the universe,” says Micheli. “Future telescopes promise to detect thousands of FRBs per month, and by that time we may find more of these periodic signals.”

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