Abstract
Cosmic rays were discovered over one hundred years ago but there are still unsolved problems. One of the hot problems is the origin of cosmic rays of the highest energies. Sources are still unclear and it is neither clear how particles gain ultra-high energies. Possible sources of cosmic rays at the highest energies are supermassive black holes. From this perspective we discuss in a popular form some recent developments in cosmic ray studies along with author’s recent results. The paper also offers materials for further reading.
Highlights
Quanta produced in cascades are the component of extragalactic background radiation
What is the origin of cosmic rays at higher energies? Latest studies indicate that ultra-high energy cosmic ray sources are located outside our galaxy, inside active galactic nuclei
The problem from which we began was how particles gained ultra-high energy in active galactic nuclei. Solving this problem we faced the challenge of supermassive black holes: what are processes of particle acceleration in the black hole vicinity? Analyzing these processes we formulated the inverse problem: is it possible to study these processes using cosmic ray data along with theoretical results? The answer is “Yes”, despite cosmic ray interactions in extragalactic space
Summary
Cosmic rays were discovered by the Austrian physicist Victor Hess in 1912. For his study he used simple portable devices—electroscopes in balloons. In 1930–1940s cosmic ray interactions with matter were studied intensively. These studies led to the discovery of new elementary particles. Physicists use different types of instruments to detect cosmic rays. These detectors can be ground-based or installed on space satellites or at high altitude balloons. Particles at energies up to 48 Joule (J) have been detected in cosmic rays. The maximal energy of particles detected in cosmic rays is about 3 × 1020 eV.
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