Using the Canadian Hydrogen Intensity Mapping Experiment (CHIME)/FRB radio telescope at the Dominion Radio Astrophysical
Observatory in British Columbia, scientists have detected thirteen fast radio bursts, or FRBs, including one that repeated as many as six times.
Fast Radio Bursts, or FRBs, which are basically highly dispersed radio signals from outside the Milky Way that last for a few milliseconds, have been baffling scientists for years, now.
What’s different about these thirteen FRBs, though, is the fact that they are brighter and have the lowest radio frequency compared to previous detections, which the researchers think has something to do with their source of origin roughly 1.5 billion lightyears away.
“It doesn’t mean that they’re traveling from further away,” study author Shriharsh Tendulkar, a postdoctoral fellow in the department of physics at McGill University, was quoted by National Geographic as saying.
“As light propagates through the hot gas and plasma in the intergalactic medium and the interstellar medium, it has a bunch of different effects on the signal,” Tendulkar said.
The fact that at least seven of the thirteen blasts detected by the CHIME/FRB instrument were as low as 400 MHz points towards the possibility of even lower frequency signals out there – too low for CHIME to pick up.
“[We now know] the sources can produce low-frequency radio waves and those low-frequency waves can escape their environment, and are not too scattered to be detected by the time they reach the Earth,” explained Tom Landecker, a CHIME team member from the National Research Council of Canada.
“That tells us something about the environments and the sources,” he said, adding: “We haven’t solved the problem, but it’s several more pieces in the puzzle.”
“Whatever the source of these radio waves is, it’s interesting to see how wide a range of frequencies it can produce,” said Arun Naidu, another CHIME team member from McGill University.
“There are some models where intrinsically the source can’t produce anything below a certain frequency,” Naidu added.
While this astrophysical phenomenon is not an uncommon occurrence, repeating series of FRBs definitely is, as this is only the second instance in sixteen years that scientists have detected a “repeater.”
FRBs never seemed to repeat themselves until FRB 121102 was first discovered on November 2, 2012, at precisely 06:35:53.244 (Date and Time [UTC] for 1581.804688 MHz) by the Peurto Rico-Arecibo Observatory radio telescope.
In 2015, Shami Chatterjee, a senior researcher at the Cornell Center for Astrophysics and Planetary Science and an international team of astronomers were able to accurately pinpoint the source of FRB 121102, which they said was a dwarf galaxy some 3 billion lightyears away from Earth – twice the distance of the latest repeater – FRB 180814.
By the way, fast radio bursts are named according to the date the signal is first detected – in the YYMMDD format prefixed by the letters FRB; which means FRB 180814 was detected on Aug 14, 2018, and the first repeater FRB 121102 was picked up on Nov 2, 2012.
“The host galaxy for this FRB appears to be a very humble and unassuming dwarf galaxy, which is less than 1 percent of the mass of our Milky Way galaxy,” Tendulkar said in a statement at the time.
“That’s surprising. One would generally expect most FRBs to come from large galaxies which have the largest numbers of stars and neutron stars — remnants of massive stars,” he added.
Although the origins of the two repeaters are 1.5 billion light years apart, there are striking structural similarities between them, notes Tendulkar.
“The fact that we see these multiple structures in the burst was very similar to the first repeating fast radio burst. This is very uncommon,” he said.
“Now there is this tantalizing evidence that these bursts’ structures are seen only in repeaters,” he concluded.
This basically means that FRBs sharing the same structure are possibly repeaters even if they don’t repeat when detected.
Determined to find more conclusive evidence, the researchers are continuing their hunt for more FRBs, keeping the CHIME/FRB instrument trained on the region of the sky where the high-speed radio bursts came from, in addition to following up on already detected FRBs with other radio telescopes.
“We are trying to build up clues and trying to understand whether the repeating fast radio bursts and single fast radio bursts are different populations,” Tendulkar said.
“Do they come from different objects? Or are they related in some way to each other? We are trying to figure these things out, so that’s really exciting,” he added.
“The CHIME discovery points to a huge potential,” said Chatterjee.
“I’m intensely curious how many [fast radio bursts] they are sitting on now. They must have dozens or hundreds,” he added.
Another pertinent question that Tendulkar and the CHIME team would probably be trying to find an answer to would be:
What cosmic event creates these millisecond-duration bursts of radio signals that reach Earth from distances of 1.5 and 3 billion lightyears and has the capacity of generating more energy than 500 million Suns?
“There is a lot of fun in the not knowing,” says Tendulkar.
“You keep adding more information, but as in all sciences, whenever you solve one mystery, it always opens up three more.”
So, are we talking about aliens here?
Unlikely, but you never know!