Abstract
In this paper, intergalactic electromagnetic cascades are used as a probe of cosmic ray sources. This is achieved as follows. In extragalactic space, cosmic rays initiate electromagnetic cascades, in which gamma-ray and neutrino emission arises. We used the joint analysis of cosmic ray data, along with extragalactic gamma-ray and neutrino emissions, to study particle acceleration in the vicinity of supermassive black holes. Particle injection spectra depend on processes of particle acceleration, and here we discuss models with various injection spectra. The computations of the propagation of cosmic rays in space were performed using the publicly available TransportCR code. It was found that a new subclass of sources might exist that does not contribute to the particle flux on Earth, instead to gamma-ray and neutrino emissions arising in electromagnetic cascades. In addition, the upper limit of the relative number of ‘exotic’ supermassive black holes surrounded by a superstrong magnetic field is derived.
Highlights
Cosmic rays (CR) at ultra-high energies (UHE) are of extragalactic origin, their sources being point-like objects
Another indication of CR interaction with background emissions is intergalactic electromagnetic cascades [3,4]; so gamma-ray and neutrino emissions produced in cascades are applied to source investigation through the data of the Fermi
We consider that UHE CRs are accelerated in the vicinity of supermassive black holes (SMBH), the CR injection spectra depend on processes of particle acceleration
Summary
Cosmic rays (CR) at ultra-high energies (UHE) are of extragalactic origin, their sources being point-like objects. These objects seem to be active galactic nuclei (AGN), where CRs are accelerated in processes in the vicinity of supermassive black holes (SMBH), which are located in the central parts of AGN. Two other parameters change during particle propagation in intergalactic space due to CR interaction with the cosmic microwave background (CMB), extragalactic background light (EBL), and radio background. This results in the GZK-effect [1,2], which is used to study space distribution of CR sources and source models. Another indication of CR interaction with background emissions is intergalactic electromagnetic cascades [3,4]; so gamma-ray and neutrino emissions produced in cascades are applied to source investigation through the data of the Fermi
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