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

Fast radio bursts are one of the greatest cosmic mysteries of our time. They are extremely powerful but extremely short explosions of electromagnetic radiation in radio wavelengths, which discharge as much energy in milliseconds as 500 million suns.

For years, scientists have wondered what could be the cause of these brief bursts, detected in galaxies millions to billions of light-years away. Then, in April 2020, we have a very strong lead: A brief, powerful flash of radio waves from something in the Milky Way – a magnetar.

This suggests that these extremely magnetized dead stars produce at least some fast radio bursts. Now physicists have come up with a way to replicate in a lab what we think happens in the early stages of these insane explosions, according to the theory of quantum electrodynamics (QED).

“Our lab simulation is a small-scale analog of a magnetic environment,” says physicist Kenan Qu from Princeton University. “This allows us to analyze QED pair plasmas.”

A magnetar is a type of dead star called a neutron star. When a massive star reaches the end of its life, it blows away its outer material and core, no longer supported by the external pressure of nuclear fusion, collapses under its own gravity to form an ultra-dense object with a powerful magnetic field. That’s the neutron star.

Some neutron stars have an even stronger magnetic field. That’s a magnet. We don’t know how they get this way, but their magnetic fields are about 1000 times more powerful than a normal neutron star, and a quadrillion times more powerful than that of the earth.

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

It is also thought that the magnetic field is responsible for transforming the matter in the space around the magnetar into a plasma composed of matter-antimatter mate. These pairs consist of a negatively charged electron and a positively charged positron, and they are thought to play a role in the emissions of the rare fast radio bursts That to repeat

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

Because the strength of the magnetic fields involved is so extreme, Qu and his colleagues devised a way to create paired plasmas in a lab by other means.

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

“It converts energy into pair plasma through so-called QED cascades. The pair plasma then shifts the laser pulse to a higher frequency. The exciting result demonstrates the prospects for creating and observing QED pair plasma in labs and allows experiments to develop theories about fast radio signals. .”

The technique involves generating a high-speed electron beam traveling at close to the speed of light. A moderately powerful laser is fired at this beam and the resulting collision creates a pair of plasma.

In addition, it slows down the resulting plasma. This could solve one of the problems found in previous experiments to create pair plasmas – observing their collective behavior.

“We think we know what laws govern their collective behavior. But until we actually produce a pair plasma in the lab that exhibits collective phenomena that we can investigate, we can’t be absolutely sure about that,” says physicist Nat Fisch from Princeton University.

“The problem is that collective behavior in pair plasmas is notoriously difficult to observe. So an important step for us was to see this as a collaborative production-observation problem, realizing that a great method of observation eases the conditions on what needs to be produced and directs us in turn to a more practical user facility.”

The observation experiment has yet to be conducted, but it provides a way to conduct these probes that were not possible before. It reduces the need for extremely powerful equipment that may be beyond our technical capabilities and budgets.

The team is currently preparing to test their ideas with a series of experiments at the SLAC National Accelerator Laboratory. This, they hope, will help them learn how magnetars generate pair plasmas, how those pair plasmas can produce rapid radio bursts, and identify what previously unknown physics might be involved.

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

“If we could observe something like a radio burst in the lab, that would be extremely exciting. But the first part is just to observe the scattering of the electron beams, and once we do, we’ll enhance the laser intensity to to higher densities to actually see the electron-positron pairs.The idea is that our experiment will evolve over the next two years or so.

So it may take a little longer to get our answers to high-speed radio bursts. But if we’ve learned anything over the years, it’s that unraveling this fascinating mystery is well worth the wait.

The team’s paper was published in Physics of plasmas

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