Cosmic rays are a common name for a bunch of different particles that fly into our planet’s atmosphere from outer space at high speed. Recently, scientists have found the sources of some of the most energetic particles.
Cosmic rays and their sources
As early as 1912, scientists discovered that the upper layers of our planet’s atmosphere are bombarded by a huge number of particles flying seemingly from nowhere. Electrons, protons, alpha particles, and neutrinos – collectively, they are called cosmic rays.
In the years since then, scientists have learned an enormous amount about the origin of cosmic rays and have identified the sources of most of them. However, what can give rise to some of the most energetic of them remains a mystery. And this is what the authors of the new study tried to find out.
Petaelectronvolt particles
In addition to the type, cosmic ray particles are characterized by their energy, which is measured in electron volts (eV) and derived units. In most cases, we are talking about MeV, GeV, and TeV, and sometimes we also see PeV. And they are the ones that cause the most problems.
They are extremely rare, perhaps one every few months, but scientists are not very sure what astronomical objects can produce them. One was identified in a high-altitude observatory, but only in the X-ray spectrum, and it still needs to be compared with the visible range.
But the researchers succeeded. The source turned out to be a pulsar wind nebula, a dust cloud that is constantly bombarded by particles flying from a neutron star. However, scientists realize that this is only the beginning of the search and that other sources of petaelectronvolt particles may be completely different.
According to phys.org
