is there life out there This has always been discussed. Some say they can attest to the fact that they have witnessed UFOs and extraterrestrial life forms. But to look for solid evidence, that has yet to be uncovered.
Still, it is the unknown that draws the others to continue the search. Now, with the advancement in technology, they’ve seen subtle glimpses that suggest there’s something out there that we may need to investigate further.
Finally, some astronomers from MIT and universities in Canada and the US were able to hear a strange and persistent radio signal from a galaxy far, far away. The signals seem to be flashing regularly, which surprised everyone.
The signal they heard was called a fast radio burst, or an FRB. That is, what they heard was an extremely powerful burst of radio waves originating from an unknown astrophysical origin. The sound often only lasts a few milliseconds at the longest. This new signal could stay on for up to three seconds, which is about 1,000 times longer than the usual FRB. In the 3-second window, the team could hear bursts of radio waves repeating every 0.2 seconds. There was obviously a periodic pattern and they compared this to a heartbeat.
The source of the signal came from a distant galaxy some billions of light-years from Earth. Where this noise came from is still unknown. The astronomers who heard it suspect the signal could have come from either a radio pulsar or a magnetar “on steroids.” These are types of neutron stars that are very dense, rapidly spinning collapsed cores derived from the giant stars.
“There aren’t many things in the universe that emit strictly periodic signals.” Daniele Michilli, a postdoc at MIT’s Institute for Astrophysics and Space Research, said. “Examples that we know of in our own galaxy are radio pulsars and magnetars that rotate and produce a radial emission similar to a lighthouse. And we think this new signal could be a magnetar or a pulsar on steroids.” She added.
The team has hope and wants to see more periodic signals coming from the same source. Once they regain access to it, this could be used as an astrophysical clock. This could mean that the frequency of the bursts, and how they change as they move away from Earth, could be used to measure the rate of growth or expansion of the universe.
The latest discovery was recently published in the journal Nature. The authors are CHIME/FRB Collaboration members, MIT co-authors Calvin Leung, Juan Mena-Parra, Kaitlyn Shin, and Kiyoshi Masui. Michilli was also part of the group and led the discovery first as a researcher at McGill University, and then he had a postdoctoral position at MIT.
So far, the signal was called FRB 20191221A by the researchers. At this point, this is believed to be the longest-lived FRB discovered to date that showed the clearest periodic pattern.
The sound of a heartbeat
The very first FRB was discovered in 2007. Since then there have been hundreds of similar radio bursts coming from different areas of the galaxy, the most recent of which came from the Canadian Hydrogen Intensity Mapping Experiment, or CHIME. This is an interferometric radio telescope composed of 4 large parabolic reflectors found at the Dominion Radio Astrophysical Observatory in British Columbia, Canada.
CHIME still watches the sky today as the earth rotates. It was specifically designed to pick up radio waves originating from hydrogen in its earliest form in the universe. The telescope is also extremely sensitive to fast radio bursts. It has done so since setting its watchful eye on the sky in 2018. Since then, CHIME has been able to discover hundreds of FRBs originating from different parts up there.
A large proportion of the observed and detected FRBs are considered unique, which are ultra-bright bursts of radio waves lasting a few milliseconds and then fading away. Now the researchers came across the first periodic FRB, which appeared to emit radio waves in regular patterns. This signal consisted of a four-day window of sporadic outbursts. This had been repeated continuously every 16 days. This specific cycle meant there was a periodic pattern of activity. However, it must be noted that the signal that came from the actual radio bursts was random rather than periodic.
Two years ago, on December 21, 2019, CHIME received a signal from a potential FRB. This caught Michilli’s attention as she was the one looking for the incoming data. “It was unusual” he shared. “Not only was it very long, lasting about three seconds, but there were periodic spikes that were remarkably precise, sending out every split second — boom, boom, boom — like a heartbeat. This is the first time that the signal itself is periodic.”
Clear sound bursts
When Michilli and his colleagues analyzed the pattern of radio bursts emanating from FRB 20191221A, they found similarities to emissions from radio pulsars and magnetars originating from our own galaxy. Radio pulsars are actually neutron stars that emit beams of radio waves that appear to beat like a heart as the star spins. Magnetars also emit similar emissions due to their extreme magnetic fields.
However, there are also differences between the new signal and the radio emissions from our own pulsars and magnetars. What makes this stand out is that FRB 20191221A appears to be more than a million times brighter. Michilli said the glowing flashes could be from a distant radio pulsar or magnetar, which isn’t typically as bright as it orbits. But for reasons they have yet to discover, it threw out a series of brilliant explosions in a unique three-second window. Luckily, CHIME was there to capture the moment.
“CHIME has now discovered many FRBs with different properties,” Michilli said. “We’ve seen some living in very turbulent clouds, while others appear to be in a clean environment. Based on the properties of this new signal, we can say that there is a plasma plume around this source, which must be extremely turbulent.”
The group remains hopeful of capturing more bursts from the periodic FRB 20191221A. This will help them better understand the source and learn more about neutron stars in general.
“This discovery raises the question of what could be causing this extreme signal, which we have never seen before, and how we can use this signal to study the universe,” explained Michilli.
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