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Active Galactic Nuclei (AGNs) and their relativistic jets belong to the most promising class of ultra-high-energy cosmic ray (UHECR) accelerators. This compact review summarises basic experimental findings by recent instruments, and…

High Energy Astrophysical Phenomena · Physics 2022-11-23 Frank M. Rieger

Active galactic nuclei (AGNs) have been one of the most widely discussed sources of ultrahigh-energy cosmic rays (UHECRs). The recent results of Pierre Auger observatory (PAO) have indicated a possible composition change of UHECRs above…

High Energy Astrophysical Phenomena · Physics 2010-01-07 Asaf Pe'er , Kohta Murase , Peter Mészáros

Active Galactic Nuclei (AGN) and their relativistic jets are believed to be potential sites of ultra-high-energy (UHE) cosmic ray acceleration. This paper reviews basic observational findings as well as requirements on source energetics,…

High Energy Astrophysical Phenomena · Physics 2019-11-12 Frank M. Rieger

Active Galactic Nuclei (AGN) are highly energetic astrophysical sources powered by accretion onto supermassive black holes in galaxies, which present unique observational signatures covering the full electromagnetic spectrum (and more) over…

High Energy Astrophysical Phenomena · Physics 2023-04-05 Stefano Bianchi , Vincenzo Mainieri , Paolo Padovani

In this paper we give a brief review of the astrophysics of active galactic nuclei (AGN). After a general introduction motivating the study of AGNs, we discuss our present understanding of the inner workings of the central engines, most…

Cosmology and Nongalactic Astrophysics · Physics 2013-01-18 Henric Krawczynski , Ezequiel Treister

The cosmic ray source spectrum produced by AGN (Active Galactic Nucleus) jets is calculated. A distinctive feature of these calculations is the account for the jet distribution on kinetic energy. The expected cosmic ray spectrum at the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 V. S. Ptuskin , S. I. Rogovaya , V. N. Zirakashvili

Active Galactic Nuclei (AGN) are sources of high-energy gamma-rays and are considered to be promising candidates to be sources of high-energy cosmic rays and neutrinos as well. We present and discuss various models for ion acceleration and…

High Energy Astrophysical Phenomena · Physics 2023-11-13 Kohta Murase , Floyd W. Stecker

Deceleration of relativistic jets from active galactic nuclei (AGNs) detected recently by MOJAVE team is discussed in connection with the interaction of the jet material with the external photon field. Appropriate energy density of the…

High Energy Astrophysical Phenomena · Physics 2016-10-12 V. S. Beskin , A. V. Chernoglazov

We discuss a representative selection of particle acceleration mechanisms believed to be operating in Active Galactic Nuclei. Starting from direct electrostatic field acceleration in the vicinity of the black hole up to Fermi-type particle…

High Energy Astrophysical Phenomena · Physics 2009-11-23 Frank M. Rieger

Jets associated with Active Galactic Nuclei (AGN) have been observed for almost a century, initially at optical and radio wavelengths. They are now widely accepted as "exhausts" produced electromagnetically by the central, spinning, massive…

High Energy Astrophysical Phenomena · Physics 2015-11-25 R. Blandford , W. East , K. Nalewajko , Y. Yuan , J. Zrake

Active galactic nuclei (AGN) are believed to be promising candidates of extragalactic cosmic-ray accelerators and sources, and associated high-energy neutrino and hadronic gamma-ray emission has been studied for many years. We review models…

High Energy Astrophysical Phenomena · Physics 2019-04-03 Kohta Murase

It is suggested that the outflowing plasma in the jets of active galactic nuclei (AGNs) is inhomogeneous and consists of separate clouds. These clouds are strongly magnetized and move away from the central engine at relativistic speeds. The…

Astrophysics · Physics 2010-12-03 V. V. Usov , M. V. Smolsky

We demonstrate that a population of Active Galactic Nuclei (AGN) can describe the observed spectrum of ultra-high-energy cosmic rays (UHECRs) at and above the ankle, and that the dominant contribution comes from low-luminosity BL Lacs. An…

High Energy Astrophysical Phenomena · Physics 2021-05-19 Xavier Rodrigues , Jonas Heinze , Andrea Palladino , Arjen van Vliet , Walter Winter

Active Galactic Nuclei (AGN) are remarkable astronomical sources emitting over the whole electromagnetic spectrum, with different bands providing unique windows on distinct sub-structures and their related physics. AGN come in a large…

High Energy Astrophysical Phenomena · Physics 2023-02-27 Paolo Padovani

The nuclei of most normal galaxies contain supermassive black holes, which can accrete gas through a disk and become active. These Active Galactic Nuclei, AGN, can form jets which are observed on scales from AU to Mpc and from meter…

High Energy Astrophysical Phenomena · Physics 2019-09-11 Roger Blandford , David Meier , Anthony Readhead

We investigate the production of ultra-high-energy cosmic ray (UHECR) in relativistic jets from low-luminosity active galactic nuclei (LLAGN). We start by proposing a model for the UHECR contribution from the black holes (BHs) in LLAGN,…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Ioana Dutan , Laurentiu I. Caramete

Jets emanating from active galactic nuclei (AGN) represent some of the most formidable particle accelerators in the universe, thereby emerging as viable candidates responsible for the detection of ultra-high-energy cosmic rays (UHECRs). If…

High Energy Astrophysical Phenomena · Physics 2025-02-25 Olmo Piana , Hung-Yi Pu

We consider the production of high energy neutrinos and cosmic rays in radio-quiet active galactic nuclei (AGN) or in the central regions of radio-loud AGN. We use a model in which acceleration of protons takes place at a shock in an…

Astrophysics · Physics 2010-11-30 A. P. Szabo , R. J. Protheroe

Active Galactic Nuclei are considered as possible sites of cosmic ray acceleration and some of them have been observed as high energy gamma ray emitters (Blazars). There naturally comes an appealing idea that the acceleration of the highest…

Astrophysics · Physics 2010-12-03 G. Henri , G. Pelletier , P. O. Petrucci , N. Renaud

We believe that the radiation we receive from Gamma-Ray Bursts (GRBs) and radio loud Active Galacti Nuclei (AGNs) originates from the transformation of bulk relativistic motion into random energy. Mechanisms to produce, collimate and…

Astrophysics · Physics 2009-11-10 G. Ghisellini
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