Professor Elaine Sadler.
Professor Sadler, also part of the School of Physics at the University of Sydney, said: “The distant galaxy where this burst originated looked quite different from the other galaxies where FRBs had been detected and we think we may be seeing the collision and merger of two galaxies rather than just a single galaxy.
“Galaxy collisions of this kind were more common in the distant and early Universe than they are today. Even though this galaxy is billions of light years away, measurements with a range of telescopes have allowed us to measure its size and mass as well as the typical age and chemical composition of its constituent stars.
“This information is helpful in trying to pin down the physical mechanism that produces such highly energetic magnetic flares, represented by the FRBs.”
Weighing the Universe
The discovery confirms that FRBs can be used to measure the 'missing' matter between galaxies, providing a new way to 'weigh' the Universe.
Current methods of estimating the mass of the Universe are giving conflicting answers and challenging the standard model of cosmology.
“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,” Associate Professor Shannon said. “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 allow us to detect this ionised 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,” he said.
Finding distant FRBs is key to accurately measuring the Universe’s missing matter, first demonstrated by the late Australian astronomer Jean-Pierre ('J-P') Macquart in a Nature paper in 2020.
Dr Ryder said: “J-P showed that the further 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.”
About 50 FRBs have been pinpointed to date – nearly half using ASKAP. The authors suggest we should be able to detect thousands of them across the sky, and at even greater distances.
Associate Professor 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.”
The result represents the limit of what is achievable with telescopes today, although astronomers will soon have the tools to detect even older and more distant bursts, pin down their source galaxies and measure the Universe’s missing matter.
The international SKA Observatory is currently building two radio telescopes in South Africa and Australia that will be capable of finding thousands of FRBs, including very distant ones that cannot be detected with current facilities.
ESO’s Extremely Large Telescope, a 39-metre telescope under construction in the Chilean Atacama Desert, will be one of the few telescopes able to study the source galaxies of bursts even further away than FRB 20220610A.
Ryder, et al. ‘A luminous fast radio burst that probes the Universe at redshift 1’, Science (October 2023) DOI: 10.1126/science.adf.2678
Funding for this research came from the Dutch Research Council, the Australian Research Council and the US National Science Foundation.