Physicists have found a way to simulate the origin of fast radio bursts

(ORDO NEWS) — Fast radio bursts are one of the biggest cosmic mysteries of our time. These are extremely powerful, but extremely short bursts of electromagnetic radiation in the radio wavelength range, releasing as much energy in milliseconds as 500 million Suns.

For years, scientists have puzzled over what might be causing these short bursts found in galaxies millions and billions of light-years away. Then, in April 2020, we got a really strong lead: a short, powerful burst of radio waves from something inside the Milky Way – a magnetar.

This suggests that at least some fast radio bursts are produced by these highly magnetized dead stars. Now physicists have figured out a way to reproduce in the lab what we think happens in the early stages of these crazy explosions, according to the theory of quantum electrodynamics (QED).

“Our lab simulation is a small-scale analogue of the magnetic medium,” says physicist Kenan Koo of Princeton University. “This allows us to analyze paired QED plasmas.”

A magnetar is a type of dead star called a neutron star. When a massive star reaches the end of its life cycle, it blows away its outer material, and the core, no longer supported by the external pressure of nuclear fusion, collapses under its own gravity, forming a superdense object with a powerful magnetic field. This is the neutron star.

Some neutron stars have even stronger magnetic fields. This is a magnetar. We don’t know how they get that way, but their magnetic fields are about 1,000 times stronger than those of a typical neutron star, and a quadrillion times stronger than those of Earth.

Scientists believe that fast radio bursts are the result of a tension between a magnetic field so powerful it distorts the shape of a magnetar and the internal pressure of gravity.

It is believed that the magnetic field is also responsible for the transformation of matter in the space around the magnetar into a plasma consisting of matter-antimatter pairs. These pairs are composed of a negatively charged electron and a positively charged positron and are thought to play a role in the emission of rare repetitive fast radio bursts.

This plasma is called a pair plasma, and it is very different from most plasmas in the universe. Ordinary plasma consists of electrons and heavier ions. Pairs of matter and antimatter in paired plasma have equal masses and spontaneously form and annihilate each other. The collective behavior of a paired plasma is very different from that of a normal plasma.

Because the strength of the magnetic fields is so extreme, Koo and his colleagues came up with a way to create twin plasmas in the lab using other means.

“Instead of simulating a strong magnetic field, we use a strong laser,” Ku explains.

“It converts the energy into a pair of plasma through the so-called QED cascades. The pair of plasma then translates the laser pulse to a higher frequency.” This exciting result demonstrates the promise of creating and observing QED pair plasmas in laboratories and allows experiments to test theories about fast radio bursts.”

The technique involves generating a high-speed electron beam that travels at close to the speed of light. A moderately powerful laser is directed at this beam, and as a result of the collision, a pair plasma is formed.

Moreover, as a result of this, the plasma slows down. This may solve one of the problems that have arisen in the course of previous experiments on the creation of a paired plasma – the observation of its collective behavior.

“We think we know what laws govern their collective behavior. But until we actually create a twin plasma in the laboratory in which collective phenomena will be observed that we can probe, we cannot be absolutely sure about this,” says the physicist. Nat Fish of Princeton University.

“The problem is that the collective behavior in paired plasmas is notoriously difficult to observe. So it was an important step for us to think of it as a joint production-observation problem, recognizing that a different method of observation softens the conditions for what should be produced, and in turn leads us to a more practical user object.”

The observational experiment is yet to be done, but it offers a way to conduct such studies that has not been possible before. It reduces the need for extremely powerful hardware that may be beyond our capabilities and budgets.”

The team is now preparing to test their ideas with a series of experiments at the SLAC National Accelerator Laboratory. This, they hope, will help them understand how magnetars generate paired plasmas, how these paired plasmas can generate fast radio bursts, and determine what previously unknown physics may be involved in this.

“In a sense, what we’re doing here is the starting point of a cascade that produces radio bursts,” says physicist Sebastian Meren of Stanford University and SLAC.

“If we could observe something like a radio burst in the laboratory, that would be extremely interesting. But at first we just observe the scattering of electron beams, and once we do that, we will improve the laser intensity to reach higher densities and see the electron “positron pairs. The idea is that our experiment will develop over the next two years or so.”

So it may be a little more time before we get answers to questions about fast radio bursts. But if there’s one thing we’ve learned over the years, it’s that unraveling this fascinating mystery is definitely worth the wait.


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