‘Fireballs’ of black hole plasma generated on Earth

June 14 () –

Oxford physicists have led the development of a novel way to experimentally produce plasma “fireballs” on Earth, opening a new frontier in laboratory astrophysics.

The new findings were published this week in Nature Communications.

Black holes and neutron stars are the most compact objects in the universe. Around these extreme astrophysical environments exist plasmas, the fourth fundamental state of matter along with solids, liquids and gases. The intense gravity of these dense objects attracts nearby matter and also causes them to fire powerful jets of plasma, mainly composed of pairs of electrons and their antimatter counterpart, positrons. While these jets are often seen in space, creating them in a laboratory has proven to be a big challenge so far.

Now, for the first time, an international team of scientists has successfully created high-density plasma beams in the laboratory containing about 10 billion electron-positron pairs. Such a high number means that the beam behaves like a true plasma (with wave activity) and not simply a collection of particles.

According to the researchers, this advance opens the door to future experiments to explore the powerful processes that occur in gamma ray bursts, GRBs (highly energetic light bursts believed to be caused by catastrophic events in outer space) and fluxes. output of active galactic nuclei, AGN (extremely bright regions in the centers of some galaxies fed by supermassive black holes).

“Laboratory generation of plasma ‘fireballs’ composed of matter, antimatter and photons is a research goal at the forefront of high-energy-density science,” he says. it’s a statement lead author Charles Arrowsmith, from the Department of Physics at the University of Oxford. “But the experimental difficulty of producing electron-positron pairs in high enough quantities has, until now, limited our understanding to purely theoretical studies.”

Together with researchers from the Rutherford Appleton Laboratory in Harwell, the group designed a novel experiment taking advantage of the HiRadMat facility at the Super Proton Synchrotron (SPS) accelerator at the European Organization for Nuclear Research (CERN) in Geneva.

The experiment produced a huge number of electron-positron pairs using 300 billion protons from the SPS accelerator. Each proton had 440 times more kinetic energy than its normal energy at rest. Because of this, when these high-energy protons collided with an atom, they had enough power to break apart the atom’s components (quarks and gluons), which then quickly came back together. to create a cascade of particles that eventually became electrons and positrons.

Basically, the beam generated at CERN had enough particles to start behaving like a true astrophysical plasma around a black hole.

The team has also developed techniques to modify the emittance of paired beams, allowing controlled studies of plasma interactions in analogues at the scale of astrophysical systems.