Detecting Cosmic Rays from a Galaxy Far, Far Away
Where do cosmic rays come from? Solving a 50-year old mystery, a collaboration of researchers has discovered it's much farther than the Milky Way.
In an article published in the journal Science (DOI: 10.1126/science.aan4338), the Pierre Auger Collaboration has definitively answered the question of whether cosmic particles from outside the Milky Way Galaxy. The article, titled “Observation of a large-scale anisotropy in the arrival directions of cosmic rays above 8 × 1018 eV,” notes that studying the distribution of the cosmic ray arrival directions is the first step in determining where extragalactic particles originate.
The collaborating scientists were able to make their recordings using the largest cosmic-ray observatory ever built, the Pierre Auger Observatory in Argentina. Included in this collaboration are David Nitz and Brian Fick, professors of physics at Michigan Technological University.
"We are now considerably closer to solving the mystery of where and how these extraordinary particles are created, a question of great interest to astrophysicists,” says Karl-Heinz Kampert, a professor at the University of Wuppertal in Germany and spokesperson for the Auger Collaboration, which involves more than 400 scientists from 18 countries.
Cosmic rays are the nuclei of elements from hydrogen to iron. Studying them gives scientists a way to study matter from outside our solar system—and now, outside our galaxy. Cosmic rays help us understand the composition of galaxies and the processes that occur to accelerate the nuclei to nearly the speed of light. By studying cosmic rays, scientists may come to understand what mechanisms create the nuclei.
Astronomer Carl Sagan once said, “The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars. We are made of starstuff.”
To put it simply, understanding cosmic rays and where they originate can help us answer fundamental questions about the origins of the universe, our galaxy and ourselves.