Black hole in the center of the Milky Way appears to be a powerful particle accelerator

The black hole at the center of the Milky Way appears to be responsible for the high-energy cosmic rays that fly through space. The peta particle accelerator in the center of our Milky Way is therefore about a hundred times more powerful than CERN’s particle accelerator, the LHC.

An international team of scientists from the HESS consortium, or the High Energy Stereoscopic System of coupled Cherenkov telescopes in Namibia, provide the explanation for the galactic particle accelerator in Nature. Cherenkov telescopes are specially designed for detecting collisions of gamma rays with particles in the atmosphere. Gamma rays themselves do not reach the Earth’s surface. The telescopes detect the so-called Cherenkov radiation that the particles give off when they slow down in the atmosphere.

Researchers have been detecting high-energy cosmic particles colliding with Earth’s atmosphere for a century. For most particles it is not possible to find out what the source is. This is due to the electrical charge of the particles, which causes them to be deflected by magnetic fields in space. Gamma rays are not affected by magnetic fields and therefore travel in a straight line from their source, which appears to consist of the large black hole at the center of the Milky Way.

The suspicion that the radiation came from somewhere in the center of the Milky Way had been around for about ten years, the UvA writes on its site. Ultimately, data collected over the last ten years by HESS together with improved data analysis methods was used. The radiation could come from different sources, but which one was not clear until now. The suspected sources were supernova remnants, clusters of massive stars and the black hole at the center of the Milky Way.

Now it turns out that it is indeed the black hole. The black hole accelerates particles as if it were a peta particle accelerator. Compared to the LHC, the accelerator is about a hundred times more powerful. The LHC allows particles with thirteen teraelectron volts to collide with each other.

Gamma ray image of Galactic center. Source: Nature