2023-10-19 20:00:20
In an article published this week in Sciencean international team led by professors Stuart Ryder from Macquarie University and Ryan Shannon from Swinburne University of Technology (both in Australia) reports the discovery of the fast radio burst (FRB, for its acronym in English), the most distant and oldest located to date, with about 8,000 million years old. Your name, FRB 20220610A.
FRB 20220610A is the oldest and most distant fast radio burst located so far, at 8 billion years old.
The discovery of this burst beat the previous recordas explained Ryder to SINC: “Until now, the oldest and most distant one we had located was FRB 20190711A, 5.2 billion years old, although a group from Caltech (USA) claimed to have found another 6.1 billion years old. In any case, the “FRBs are such a fluid field that it is possible that other teams searching for these bursts and their host galaxies would have confirmed a more distant one and not yet announced it; but for now, we still hold the record.”
The source of this radio burst, which lasts much less than a second, appears to be in a group of two or three galaxies that are mergingaccording to observations.
One of the most energetic FRBs
On June 10, 2022, the radiotelescopio ASKAP, that the Commonwealth Scientific and Industrial Research Organization (CSIRO) has in Australia, was used to detect a fast radio burst created in a cosmic event, which released, in a matter of milliseconds, the equivalent of the total emission of our Sun for 30 years. It is one of the most energetic FRBs ever observed.
In a fraction of a second, the equivalent of the energy emission of our Sun for 30 years was released.
“Thanks to ASKAP’s array of satellite dishes, we were able to determine precisely where the burst was coming from,” explains Ryder. “We then used the Very Large Telescope (VLT) of the European Southern Observatory (ESO) in Chile to search for the source galaxy, discovering that it was older and further away than any other FRB source found to date, and probably within a small group of merging galaxies.”
Illustration of the burst FRB 20220610A and the instruments used to study it. / Carl Knox (OzGrav/Swinburne University)
A help to ‘weigh’ the universe
The finding of FRB 20220610A also confirms that these types of bursts can be used to measure matter ‘missing’ between galaxies, providing a new way to ‘weigh’ the universe. This is helpful at a time when current methods for estimating the mass of the cosmos offer contradictory answers and they challenge the standard model of cosmology.
FRBs like these can be used to measure ‘missing’ matter between galaxies, providing a new way to ‘weigh’ the universe
Shannon explains: “If we count the amount of normal matter in the universe (the atoms we are made of) we find that more than half missing than there should be today, and we believe that this missing matter is hidden in the space between galaxies, but it may be so hot and diffuse that it is impossible to see it using normal techniques.
“Fast radio bursts detect this ionized material,” continues the expert. “Even in a space that is almost perfectly empty, they can ‘see’ all the electronsand that allows us to measure how much matter there is between the galaxies,” he says.
Ryder details it: “The FRB signal we detected has a printed record of how many electrons it passed through to get from its point of origin to Earth. If we compare it with the distance at which its host galaxy is located, deduced from its optical spectrum (using the Doppler effect), we get the density of these electrons, each of which was stripped of one atom. If we multiply the density by the volume of space around us, we obtain an estimate of the total mass of atoms, many of which do not appear in any other form.
The Macquart relationship
Therefore, detecting distant FRBs is key to accurately measuring the ‘missing’ matter of the universe, as already pointed out by the late Australian astronomer Jean-Pierre (JP) Macquart in 2020.
“JP showed that the further away a fast radio burst is, the more diffuse gas reveals among the galaxies. This is now known as the Macquart relation (‘dispersion’ of the FRB – the sum of electrons it probes – versus the distance from the galaxy it comes from). “Some recent FRBs appeared to break this relationship, but our measurements confirm that it extends beyond half of the known universe,” Ryder says.
“The discovery of FRB 20220610A is significant because it helps ‘anchor’ the upper end of the Macquart relationship,” he emphasizes. “Even so, it is above a simple extrapolation from the closest FRBs, either because there is a excess electrons between us and the burst (for example, if it passes through the haloes of foreground galaxies in that same general direction), or perhaps due to hot gas from a nebula immediately surrounding the magnetar [estrella de neutrones con un potentísimo campo magnético] which we believe gave rise to the FRB. “We will have to find more such objects to find out which effect dominates.”
About 50 fast radio bursts have been detected so far, but what causes these massive bursts of energy remains unknown.
To date, about 50 FRBs have been detected, almost half thanks to ASKAP, but the origin of these fleeting ones remains unknown. radiation pulsescaused by mysterious high-energy astrophysical processes.
“Although we still don’t know what causes them, the paper confirms that fast radio bursts are common events in the universe and that we can use them to detect matter between galaxies and better understand the structure of the universe,” Shannon emphasizes.
Better detection tools are coming
The team also showed that 8 billion yearslike those of FRB 20220610A, is the maximum time that we can expect to see and locate fast radio bursts with the current telescopes. But it also suggests that we should be able to detect thousands of these bursts across the sky, and at even greater distances, with the help of new tools already on the way.
The astronomical community will soon have them to detect even older and more distant bursts, pinpoint their parent galaxies and measure the matter that is missing in the universe.
Currently, with the international project Square Kilometre Array (WILL) Two radio telescopes are being built in South Africa and Australia that will be capable of detecting thousands of FRBs, including some very distant ones that cannot be detected with current facilities.
For its part, the future Extremely Large Telescope (ELT) ESO’s 39-metre telescope being built in Chile’s Atacama Desert will be one of the few capable of studying the galaxies where these radio bursts originate, even those further away than FRB 20220610A.
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