Scientists simulate origin of mysterious radio bursts from deep space

Mysterious fast radio bursts release as much energy as the sun pours out in a year - and now scientists believe they can reproduce their origin in a lab.

Fast radio bursts are bright pulses of radio emission mere milliseconds in duration, thought to originate from distant galaxies.

Researchers believe that what produces the bursts are celestial bodies such as collapsed neutron stars called magnetars (magnet + star) enclosed in extreme magnetic fields.

These fields are so strong that they turn the vacuum in space into an exotic plasma composed of matter and antimatter, in the form of pairs of negatively charged electrons and positively charged positrons, according to quantum electrodynamic (QED) theory.

Read more: What are fast radio bursts, and why do they look like aliens?

Emissions from these pairs are believed to be responsible for the powerful fast radio bursts.

“Our laboratory simulation is a small-scale analogue of a magnetar environment,” said physicist Kenan Qu, of the Princeton Department of Astrophysical Sciences.

“This allows us to analyse QED pair plasmas,” said Qu.

“Rather than simulating a strong magnetic field, we use a strong laser. It converts energy into pair plasma through what are 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 laboratories and enabling experiments to verify theories about fast radio bursts.”

The unique simulation the paper proposes creates high-density QED pair plasma by colliding the laser with a dense electron beam travelling near the speed of light.

This approach is cheap when compared with the commonly proposed method of colliding ultra-strong lasers to produce the QED cascades.

Read more: Telescope detects 100 mysterious radio signals from billions of light years away

The approach also slows the movement of plasma particles, thereby allowing stronger collective effects.

“No lasers are strong enough to achieve this today and building them could cost billions of dollars,” Qu said.

“Our approach strongly supports using an electron beam accelerator and a moderately strong laser to achieve QED pair plasma. The implication of our study is that supporting this approach could save a lot of money.”

Preparations are currently under way for testing the simulation with a new round of laser and electron experiments at SLAC.

“In a sense what we are doing here is the starting point of the cascade that produces radio bursts,” said Sebastian Meuren, a SLAC researcher and former postdoctoral visiting fellow at Princeton University who co-authored the two papers with Qu and Fisch.

“If we could observe something like a radio burst in the laboratory that would be extremely exciting.

“But the first part is just to observe the scattering of the electron beams and once we do that we’ll improve the laser intensity to get 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.”

The overall goal of this research is understanding how bodies like magnetars create pair plasma and what new physics associated with fast radio bursts are brought about, Qu said.

“These are the central questions we are interested in.”

Watch: Astronomers pinpoint source of fast radio bursts