Fast radio burst traveled 8 billion light-years to Earth
Fast radio bursts are powerful bursts of radio emission that scientists are still trying to explain. Most are thought to have originated from outside our Milky Way galaxy. But astronomers are starting to detect them within our galaxy, too. On October 19, 2023, the European Southern Observatory (ESO) reported that an international team of scientists has found the most distant known fast radio burst yet. It’s in a small group of merging galaxies 8 billion light-years away. Not surpringly, to be able to see it across such a large distance, the fast radio burst is also one of the most energetic yet.
The most distant fast radio burst so far
The ASKAP radio telescope in Australia was the first to detect the distant fast radio burst, named FRB 20220610A, in June 2022. Incredibly, it broke the record for ASKAP’s previous “most distant” fast radio burst by a whopping 50%. Later, astronomers used ESO’s Very Large Telescope (VLT) in Chile to determine which galaxy the fast radio burst came from. Lead author Stuart Ryder, an astronomer at Macquarie University in Australia, said:
Using ASKAP’s array of dishes, we were able to determine precisely where the burst came from. Then we used [ESO’s VLT] in Chile to search for the source galaxy, finding it to be older and further away than any other fast radio bursts source found to date and likely within a small group of merging galaxies.
Like with other fast radio bursts, the radio signals were extremely brief in duration. They only lasted for less than a millisecond, or one-thousandth of a second. Yet amazingly, in that tiny flicker of time, the fast radio burst released the equivalent of our sun’s total emission over a period of 30 years.
Measuring ‘missing matter’ in the universe
The researchers said that this new fast radio burst is in a group of merging galaxies. There’s an added bonus to that discovery. According to the researchers, this shows that fast radio bursts can be used to help find the missing matter in the universe and “weigh” the mass of galaxies. This is matter that current calculations say should exist between galaxies but can’t be directly observed. As co-author Ryan Shannon at the Swinburne University of Technology in Australia explained:
If we count up the amount of normal matter in the universe – the atoms that we are all made of – we find that more than half of what should be there today is missing. We think that the missing matter is hiding in the space between galaxies, but it may just be so hot and diffuse that it’s impossible to see using normal techniques.
Fast radio bursts sense this ionized material. Even in space that is nearly perfectly empty, they can ‘see’ all the electrons, and that allows us to measure how much stuff is between the galaxies.
In fact, scientists had already shown that fast radio bursts are essential to measuring the universe’s missing matter. The late Australian astronomer Jean-Pierre Macquart discovered that in 2020. And Ryder noted:
J-P showed that the farther away a fast radio burst is, the more diffuse gas it reveals between the galaxies. This is now known as the Macquart relation. Some recent fast radio bursts appeared to break this relationship. Our measurements confirm the Macquart relation holds out to beyond half the known universe.
A better understanding of the universe
In addition, if scientists can better understand fast radio bursts, then they can gain a better understanding of the universe overall. Shannon said:
While we still don’t know what causes these massive bursts of energy, the paper confirms that fast radio bursts are common events in the cosmos and that we will be able to use them to detect matter between galaxies and better understand the structure of the universe.
Even more distant fast radio bursts?
FRB 20220610A is the most distant fast radio burst astronomers have found so far. But there are likely others even farther from us. And new telescopes coming online should be able to spot them. The international Square Kilometre Array Observatory (SKAO) will have two new radio telescopes in South Africa and Australia that will be able to find thousands of fast radio bursts. This includes ones that are so far away they cannot be detected with current facilities. ESO’s upcoming Extremely Large Telescope (ELT) will also be able to study the source galaxies of fast radio bursts even farther away than FRB 20220610A.
In 2020, astronomers announced the discovery of the closest fast radio burst found so far. That one was about 30,000 light-years away and within our own Milky Way galaxy.
More about fast radio bursts
Just what is a fast radio burst, anyway? They are extremely powerful bursts of radio waves, mostly detected in extragalactic space. They are kind of like pulsars, but much stronger, and scientists still debate their origins. The bursts tend to be brief, measured in milliseconds (one-thousandth of a second), but some last longer (up to three seconds).
Most fast radio bursts seem to occur only once, but astronomers have been discovering more that repeat. One fast radio burst, for example, repeats in a 16-day cycle. With that in mind, scientists think that there are likely different kinds of fast radio bursts, some that repeat and some that don’t.
Bottom line: Astronomers have confirmed the most distant fast radio burst ever found so far. It resides in a small group of merging galaxies 8 billion light-years away.