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Title: Neutrino and cosmic-ray emission and cumulative background from radiatively inefficient accretion flows in low-luminosity active galactic nuclei

Abstract

We study high-energy neutrino and cosmic-ray (CR) emission from the cores of low-luminosity active galactic nuclei (LLAGN). In LLAGN, the thermalization of particles is expected to be incomplete in radiatively inefficient accretion flows (RIAF), allowing the existence of non-thermal particles. In this work, assuming stochastic particle acceleration due to turbulence in RIAFs, we solve the Fokker–Planck equation and calculate spectra of escaping neutrinos and CRs. The RIAF in LLAGN can emit CR protons with ≳10 PeV energies and TeV–PeV neutrinos generated via pp and/or pγ reactions. We find that, if ∼1% of the accretion luminosity is carried away by non-thermal ions, the diffuse neutrino intensity from the cores of LLAGN may be as high as E{sub ν}{sup 2}Φ{sub ν}∼3×10{sup −8} GeV cm{sup −2} s{sup −1} sr{sup −1}, which can be compatible with the observed IceCube data. This result does not contradict either of the diffuse gamma-ray background observed by Fermi or observed diffuse CR flux. Our model suggests that, although very-high-energy gamma-rays may not escape, radio-quiet active galactic nuclei with RIAFs can emit GeV gamma-rays, which could be used for testing the model. We also calculate the neutron luminosity from RIAFs of LLAGN, and discuss a strong constraint on themore » model of jet mass loading mediated by neutrons from the diffuse neutrino observation.« less

Authors:
;  [1];  [2]
  1. Astronomical Institute, Tohoku University, Sendai 980-8578 (Japan)
  2. Institute for Advanced Study, Princeton, NJ 08540 (United States)
Publication Date:
OSTI Identifier:
22883041
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 806; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.; Journal ID: ISSN 0004-637X
Country of Publication:
United Kingdom
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; ACCRETION DISKS; COSMIC RADIATION; EMISSION; EQUATIONS; GALAXY NUCLEI; GAMMA RADIATION; ICECUBE NEUTRINO DETECTOR; LUMINOSITY; MASS; NEUTRINOS; NEUTRONS; PEV RANGE; SPECTRA; STOCHASTIC PROCESSES; TEV RANGE; THERMALIZATION; TURBULENCE

Citation Formats

Kimura, Shigeo S., Toma, Kenji, and Murase, Kohta. Neutrino and cosmic-ray emission and cumulative background from radiatively inefficient accretion flows in low-luminosity active galactic nuclei. United Kingdom: N. p., 2015. Web. doi:10.1088/0004-637X/806/2/159.
Kimura, Shigeo S., Toma, Kenji, & Murase, Kohta. Neutrino and cosmic-ray emission and cumulative background from radiatively inefficient accretion flows in low-luminosity active galactic nuclei. United Kingdom. https://doi.org/10.1088/0004-637X/806/2/159
Kimura, Shigeo S., Toma, Kenji, and Murase, Kohta. 2015. "Neutrino and cosmic-ray emission and cumulative background from radiatively inefficient accretion flows in low-luminosity active galactic nuclei". United Kingdom. https://doi.org/10.1088/0004-637X/806/2/159.
@article{osti_22883041,
title = {Neutrino and cosmic-ray emission and cumulative background from radiatively inefficient accretion flows in low-luminosity active galactic nuclei},
author = {Kimura, Shigeo S. and Toma, Kenji and Murase, Kohta},
abstractNote = {We study high-energy neutrino and cosmic-ray (CR) emission from the cores of low-luminosity active galactic nuclei (LLAGN). In LLAGN, the thermalization of particles is expected to be incomplete in radiatively inefficient accretion flows (RIAF), allowing the existence of non-thermal particles. In this work, assuming stochastic particle acceleration due to turbulence in RIAFs, we solve the Fokker–Planck equation and calculate spectra of escaping neutrinos and CRs. The RIAF in LLAGN can emit CR protons with ≳10 PeV energies and TeV–PeV neutrinos generated via pp and/or pγ reactions. We find that, if ∼1% of the accretion luminosity is carried away by non-thermal ions, the diffuse neutrino intensity from the cores of LLAGN may be as high as E{sub ν}{sup 2}Φ{sub ν}∼3×10{sup −8} GeV cm{sup −2} s{sup −1} sr{sup −1}, which can be compatible with the observed IceCube data. This result does not contradict either of the diffuse gamma-ray background observed by Fermi or observed diffuse CR flux. Our model suggests that, although very-high-energy gamma-rays may not escape, radio-quiet active galactic nuclei with RIAFs can emit GeV gamma-rays, which could be used for testing the model. We also calculate the neutron luminosity from RIAFs of LLAGN, and discuss a strong constraint on the model of jet mass loading mediated by neutrons from the diffuse neutrino observation.},
doi = {10.1088/0004-637X/806/2/159},
url = {https://www.osti.gov/biblio/22883041}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 806,
place = {United Kingdom},
year = {Sat Jun 20 00:00:00 EDT 2015},
month = {Sat Jun 20 00:00:00 EDT 2015}
}