Scientists at the Leibniz Institute for Astrophysics (AIP) in Potsdam have discovered a new type of plasma instability that promises to change our understanding of the origin of cosmic rays and their dynamic impact on galaxies.

At the beginning of the last century, Victor Hess discovered a new phenomenon called cosmic rays, which later brought him the Nobel Prize. He made high-altitude balloon flights to discover that the Earth’s atmosphere was not ionized by the Earth’s radioactivity. Instead, it confirmed that the origin of the ionization was extraterrestrial. Cosmic “rays” were later discovered to consist of charged particles from space moving at speeds close to the speed of light, rather than radiation. But the name “cosmic rays” survived these discoveries.

In the new study, AIP scientists and the study’s lead author, Dr. Mohamad Shalabi and his colleagues performed numerical simulations to follow the trajectories of many cosmic ray particles and study how they interact with the surrounding plasma of electrons. and protons. Article appears on pre-rendering server arXiv.

When the researchers examined cosmic rays flying from one side of the simulation to the other, they discovered a new phenomenon that excites electromagnetic waves in the background plasma. These waves influence cosmic rays, which change their winding path.

Most importantly, this new phenomenon can be best understood if we consider that cosmic rays do not act as individual particles, but instead support a collective electromagnetic wave. When this wave interacts with the background fundamental waves, it is greatly amplified and energy transfer occurs.

“This understanding allows us to believe that cosmic rays behave as radiation in this context and not as individual particles, as Viktor Hess originally thought,” says Professor Christoph Pfrommer, head of AIP’s department of cosmology and high energy astrophysics. . A good analogy for this behavior is that individual water molecules work together to form a wave that crashes onto the shore.

Dr. Mohamad Shalabi explains: “This progress comes from considering only smaller scales that have not been considered before and challenges the use of effective hydrodynamic theories in the study of plasma processes.”

This newly discovered plasma instability has many applications; these include the first description of how electrons in hot interstellar plasma can be accelerated to high energies in supernova remnants.

“This newly discovered plasma instability represents a major leap forward in our understanding of the acceleration process and finally explains why these supernova remnants shine in radio and gamma rays,” says Mohamad Shalabi. Additionally, this groundbreaking discovery opens the door to a deeper understanding of the fundamental processes of cosmic ray transport in galaxies; This is the greatest mystery in our understanding of the processes that shape galaxies during their cosmic evolution. Source