Space and Physics
PUBLISHED
What you'll discover in this article
- A fast radio burst was discovered coming from over 10 billion light-years away.
- It comes from a galaxy much smaller and lighter than the average source of these events.
- “What is particularly exciting is that this is showing us that FRBs can be detected and used as cosmological probes much further back in the history of the universe than our previous samples,” the lead authors told IFLScience.
Fast radio bursts are nothing short of prodigious. In a fraction of a second, they pack the energy that our Sun would produce over several days. These powerful emissions of radio waves come to us from the distant universe, but none as far as the newly detected FRB 20240304B.
The research, led by Dr Manisha Caleb and Dr Themiya Nanayakkara from the University of Sydney, unveiled an extraordinary event. It more than doubles the previous distance record, and it will be useful for more than just studying these events. It will help probe the distribution of matter between galaxies.
FRBs are incredibly useful because they act almost like cosmic flashlights.
Dr Manisha Caleb and Dr Themiya Nanayakkara
“We have detected and localised a fast radio burst from a galaxy at a redshift of 2.148, meaning the radio light travelled for more than 10 billion years before reaching us,” the authors told IFLScience.
“To put that into a human perspective, the light left its source long before the Earth or even the Solar System existed. The Earth and Solar System formed only about 4.5 billion years ago, so when this burst began its journey, there was no Earth, no Sun and no human life. In fact, the universe itself was only a few billion years old.”
An unexpected galaxy
The source of FRBs is uncertain. Many are believed to be produced by magnetars – a type of neutron star with an incredible magnetic field – interacting while orbiting another object. Some might have different origins, like the merger of neutron stars or black holes.
As the light from these events travels, it is affected by the matter that exists between galaxies, even when it has such low density that we can’t normally see it.
“FRBs are incredibly useful because they act almost like cosmic flashlights. As the radio pulse travels towards us, it passes through gas in galaxies, galaxy halos and the more diffuse material between galaxies,” the authors explained.
“This material leaves an imprint on the signal, particularly through its dispersion. By studying that imprint, we can work out the structure of the otherwise invisible matter and the magnetic fields between us and the source.”
This is easier said than done. While FRBs start off powerful, by the time they reach Earth the signal is 1,000 times fainter than trying to pick up a cellphone on the Moon. Still, humanity has built incredible detectors.
FRB 20240304B was detected by South Africa’s MeerKAT radio telescope, which is currently growing into the Square Kilometer Array Observatory.
The team looked for a host galaxy, but ground-based observatories were not able to find anything. They were very confident about the precision they got from the radio observations, so they applied for some JWST time, and they were awarded some.
They found something pretty special. The host galaxy is 100 times smaller than the average of all previous known hosts for FRBs. Small, but not inactive. And that’s what matters.
“What we find is that the FRB is associated with a galaxy that is actively forming stars. This is consistent with the picture that at least some FRBs are produced by young, highly magnetised neutron stars - magnetars - which are expected to be associated with the deaths of massive stars,” the authors told IFLScience.
With a sufficiently large sample, we can start mapping the matter between galaxies.
Dr Manisha Caleb and Dr Themiya Nanayakkara
“At the same time, FRBs are clearly a diverse population, and we don't think every FRB necessarily has the same origin. What observations like this give us is another piece of the puzzle: by studying the host galaxies and the environments of FRBs across cosmic time, we can start to understand which types of galaxies and stellar environments produce them.”
Hopefully the first of many
The team is planning to look for a whole population of FRBs at these cosmic distances, and they have been awarded time on JWST to follow up on any possible signals over the next three years.
“We want to find more high-redshift FRBs, localise them to their host galaxies, and use facilities such as MeerKAT and JWST together to study both the bursts and their environments. With a sufficiently large sample, we can start mapping the matter between galaxies and measuring how the baryons in the universe are distributed over cosmic time,” the authors explained.
“What is particularly exciting is that this is showing us that FRBs can be detected and used as cosmological probes much further back in the history of the Universe than our previous samples.”
The study is published in the journal Science.
