In a breakthrough discovery, scientists believe they have traced the origin of high energy cosmic rays to massive extra galactic black holes.
Cosmic rays were first discovered in the early 20th century when scientists noticed that there was more radiation in the environment, than known sources of natural radioactive background activity could account for. In 1912, Austrian scientist Victor Hess declared the presence of mysterious rays cosmic after discovering that they were from outer space.
Cosmic rays are sub-atomic particles that have a large range of energies, from a few billion to 10 to the power of 20 electron-volts (eV). Low-energy rays bombard the Earth’s surface frequently but high-energy rays are rare. During the two year long experiment at the Pierre Auger Observatory in western Argentina, 300 scientists from across the world gathered to observe the cosmic rays and solve a century old mystery. The observatory has twenty four telescopes and 1600 detectors.
Scientists detected only twenty-eight rays that fitted their criterion. They ignored rays that emerged from blackholes and supernovae in the Milky Way galaxy as they were of low-energy. Extra-galactic rays which were between forty and sixty eV couldn’t be taken into consideration as their trajectories were too bent and their origin couldn’t be traced. Also, rays that had traveled for more than 300 million years weren’t suitable for study as their energy would have reduced over the long journey.
From the twenty-eight rays, scientists discovered that high-energy rays emanate from what are known as Active Galactical Nuclei (AGNs). AGNs are nothing but massive black holes which simultaneously dispose off material and emanate plasma rays which contain high-energy particles. Of the twenty eight rays studied, twenty were observed near known AGNs, while six of the remaining eight came from directions which are probably obscured by matter in our own galaxy.
Based on these findings, scientists can soon find out what accelerates these particles and the exact sources of cosmic rays. Scientists believe that the cosmic rays will provide clues for the location of unknown AGNs. The research also takes the study of the universe to a new level as this is the first time charged particles were used to study celestial objects outside our galaxy instead of wavelengths of light.