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Title: “ESPRESSO” ACCELERATION OF ULTRA-HIGH-ENERGY COSMIC RAYS

Abstract

We propose that ultra-high-energy (UHE) cosmic rays (CRs) above 10{sup 18} eV are produced in relativistic jets of powerful active galactic nuclei via an original mechanism, which we dub “espresso” acceleration: “seed” galactic CRs with energies ≲10{sup 17} eV that penetrate the jet sideways receive a “one-shot” boost of a factor of ∼Γ{sup 2} in energy, where Γ is the Lorentz factor of the relativistic flow. For typical jet parameters, a few percent of the CRs in the host galaxy can undergo this process, and powerful blazars with Γ ≳ 30 may accelerate UHECRs up to more than 10{sup 20} eV. The chemical composition of espresso-accelerated UHECRs is determined by that at the Galactic CR knee and is expected to be proton-dominated at 10{sup 18} eV and increasingly heavy at higher energies, in agreement with recent observations made at the Pierre Auger Observatory.

Authors:
 [1]
  1. Department of Astrophysical Sciences, Princeton University, 4 Ivy Ln., Princeton NJ 08544 (United States)
Publication Date:
OSTI Identifier:
22518869
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal Letters
Additional Journal Information:
Journal Volume: 811; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 2041-8205
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; COSMIC PROTONS; COSMIC RADIO SOURCES; EEV RANGE; GALAXIES; GALAXY NUCLEI; JET MODEL; RELATIVISTIC RANGE

Citation Formats

Caprioli, Damiano, E-mail: caprioli@astro.princeton.edu. “ESPRESSO” ACCELERATION OF ULTRA-HIGH-ENERGY COSMIC RAYS. United States: N. p., 2015. Web. doi:10.1088/2041-8205/811/2/L38.
Caprioli, Damiano, E-mail: caprioli@astro.princeton.edu. “ESPRESSO” ACCELERATION OF ULTRA-HIGH-ENERGY COSMIC RAYS. United States. doi:10.1088/2041-8205/811/2/L38.
Caprioli, Damiano, E-mail: caprioli@astro.princeton.edu. Thu . "“ESPRESSO” ACCELERATION OF ULTRA-HIGH-ENERGY COSMIC RAYS". United States. doi:10.1088/2041-8205/811/2/L38.
@article{osti_22518869,
title = {“ESPRESSO” ACCELERATION OF ULTRA-HIGH-ENERGY COSMIC RAYS},
author = {Caprioli, Damiano, E-mail: caprioli@astro.princeton.edu},
abstractNote = {We propose that ultra-high-energy (UHE) cosmic rays (CRs) above 10{sup 18} eV are produced in relativistic jets of powerful active galactic nuclei via an original mechanism, which we dub “espresso” acceleration: “seed” galactic CRs with energies ≲10{sup 17} eV that penetrate the jet sideways receive a “one-shot” boost of a factor of ∼Γ{sup 2} in energy, where Γ is the Lorentz factor of the relativistic flow. For typical jet parameters, a few percent of the CRs in the host galaxy can undergo this process, and powerful blazars with Γ ≳ 30 may accelerate UHECRs up to more than 10{sup 20} eV. The chemical composition of espresso-accelerated UHECRs is determined by that at the Galactic CR knee and is expected to be proton-dominated at 10{sup 18} eV and increasingly heavy at higher energies, in agreement with recent observations made at the Pierre Auger Observatory.},
doi = {10.1088/2041-8205/811/2/L38},
journal = {Astrophysical Journal Letters},
issn = {2041-8205},
number = 2,
volume = 811,
place = {United States},
year = {2015},
month = {10}
}