Mysterious radio signal in space traced to nearby galaxy similar to our Milky Way, say scientists
The researchers achieved a level of resolution high enough to localize the FRB to a region approximately seven light-years across — a feat comparable to an individual on Earth being able to distinguish a person on the Moon
An international team of scientists has followed a mysterious repeating radio signal — intense cosmic flashes of energy that last only milliseconds — back to its source, a galaxy quite similar to ours.
This newly discovered repeating radio signal — also called Fast Radio Bursts (FRB) — is an outlier. According to experts, it is different from other FRBs because it did not originate from the expected source: dwarf galaxies. The discovery deepens the mystery over how radio signals are created.
"Identifying the host galaxy for FRBs is critical to tell us about what kind of environments FRBs live in, and thus what might actually be producing FRBs.This is a question for which scientists are still grasping at straws," says Sarah Burke-Spolaor, assistant professor of physics and astronomy and co-author of the study.
Though there have been records of hundreds of radio signals before, scientists have only been able to accurately locate the source of four signals until now, including both repeaters and non-repeaters — the two primary types of fast radio bursts.
The recently discovered radio signal is a repeater, which flashes multiple times while non-repeaters are one-off events.
The new discovery makes it the second record of repeaters. The host galaxy of this FRB looks similar to our Milky Way. It is a spiral and a massive, star-forming galaxy, explains Mohit Bhardwaj, study co-author and McGill University doctoral student.
"This is quite different from the host of the first repeating FRB source — star-forming, dwarf (low-mass) irregular galaxy," Bhardwaj tells MEA WorldWide (MEAWW).
This small dwarf galaxy containing stars and metals gave out the first recorded repeating signals dubbed FRB 121102. The nature of the host galaxy led researchers to believe that repeating FRBs are produced by neutron stars with powerful magnetic fields, also called magnetars.
"This discovery represented the first piece of the puzzle but it also raised more questions than it solved, such as whether there was a fundamental difference between repeating and non-repeating FRBs," Benito Marcote, lead study author from the Joint Institute for VLBI in Europe, which turns a global network of telescopes into a single observatory, tells CNN.
Scientists recorded the second repeater on June 19, 2019. Spreading out for over five hours, the bursts lasted for less than two-thousandths of a second.
To trace the source of the repeating radio signals, the international team of researchers put telescopes, spanning locations from the UK to China, to use. Using a technique called Very Long Baseline Interferometry, the team was able to combine the power of the telescopes and identify the source: a galaxy that was seven light-years across.
"Now, we have localized a second repeating FRB, which challenges our previous ideas on what the source of these bursts could be," explains Marcote.
The new FRB is the closest yet discovered, Bhardwaj tells MEAWW. This means that researchers can carry out follow-up studies, which was not possible earlier. He adds, "It is possible that there is more than one way to produce FRBs. Future follow-up observations will shed more light on this."
The study was published in Nature.