Neutrino and Cosmic-Ray Emission and Cumulative Background From Radiatively Inefficient Accretion Flows in Low-Luminosity Active Galactic Nuclei

Kimura, Shigeo S.; Murase, Kohta; Toma, Kenji

doi:10.1088/0004-637x/806/2/159

Cited by 136 publications

(187 citation statements)

References 101 publications

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“…The CRs are likely to exist inside accretion flows when the mass accretion rate is sufficiently lower than the Eddington rate (e.g., Kimura et al 2014). The existence of CRs is expected from the theoretical estimate (e.g., Kimura et al 2015), numerical simulations (e.g., Hoshino 2015), and modeling of the observed photon spectra (e.g., Nemmen et al 2014), although gamma rays from accretion flows have not yet been detected (Wojaczynski et al 2015).…”

Section: Discussionmentioning

confidence: 97%

“…This process has been analytically formulated using the quasi-linear theory, and the evolution of the momentum distribution function of the CRs has usually been described by the diffusion equation in momentum space (e.g., Schlickeiser & Miller 1998;Stawarz & Petrosian 2008;Ohira 2013). Kimura et al (2015) investigate stochastic acceleration inside RIAFs of low-luminosity active galactic nuclei by using this formulation, and they find that CRs can be accelerated up to ∼10 PeV if the turbulence is on the Kolmogorov spectrum and that high-energy neutrinos generated through the interaction between CRs and background matter are compatible with the IceCube events (Aartsen et al 2013(Aartsen et al , 2015. Protons escaping from RIAFs interact with circumnuclear matter and emit gamma rays (Fujita et al 2015), which can be consistent with the observed TeV flux from Sgr A * (Aharonian et al 2009b) and Cen A (Aharonian et al 2009a).…”

Section: Introductionmentioning

confidence: 99%

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Stochastic Particle Acceleration in Turbulence Generated by Magnetorotational Instability

Kimura¹,

Toma²,

Suzuki³

et al. 2016

ApJ

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We investigate stochastic particle acceleration in accretion flows. It is believed that magnetorotational instability (MRI) generates turbulence inside accretion flows and that cosmic rays (CRs) are accelerated by the turbulence. We calculate equations of motion for CRs in the turbulent fields generated by MRI with the shearing box approximation and without back reaction to the field. Our results show that the CRs randomly gain or lose their energy through interaction with the turbulent fields. The CRs diffuse in the configuration space anisotropically: the diffusion coefficient in the direction of the unperturbed flow is about 20 times higher than the Bohm coefficient, while those in the other directions are only a few times higher than the Bohm. The momentum distribution is isotropic and its evolution can be described by the diffusion equation in momentum space where the diffusion coefficient is a power-law function of the CR momentum. We show that the shear acceleration works efficiently for energetic particles. We also cautiously note that in the shearing box approximation, particles that cross the simulation box many times along the radial direction undergo unphysical runaway acceleration by the Lorentz transformation, which needs to be taken into account with special care.

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Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Stochastic Particle Acceleration in Turbulence Generated by Magnetorotational Instability

Kimura¹,

Toma²,

Suzuki³

et al. 2016

ApJ

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“…Many papers discuss the neutrino emission from one specific source class by adopting a modeldependent approach, for active galactic nuclei (AGNs) [9][10][11][12][13][14][15][16][17][18], star-forming galaxies [19][20][21][22][23][24][25][26][27][28], gamma-ray bursts [29][30][31][32][33][34][35][36], galaxy clusters [37][38][39][40], and dark matter decays [41][42][43][44][45].…”

Section: Tomographic Constraints On High-energy Neutrinos Of Hadronucmentioning

confidence: 99%

Tomographic Constraints on High-Energy Neutrinos of Hadronuclear Origin

2015

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Mounting evidence suggests that the TeV-PeV neutrino flux detected by the IceCube telescope has mainly an extragalactic origin. If such neutrinos are primarily produced by a single class of astrophysical sources via hadronuclear (pp) interactions, a similar flux of gamma-ray photons is expected. For the first time, we employ tomographic constraints to pinpoint the origin of the IceCube neutrino events by analyzing recent measurements of the cross correlation between the distribution of GeV gamma rays, detected by the Fermi satellite, and several galaxy catalogs in different redshift ranges. We find that the corresponding bounds on the neutrino luminosity density are up to 1 order of magnitude tighter than those obtained by using only the spectrum of the gamma-ray background, especially for sources with mild redshift evolution. In particular, our method excludes any hadronuclear source with a spectrum softer than E −2.1 as a main component of the neutrino background, if its evolution is slower than ð1 þ zÞ 3 . Starburst galaxies, if able to accelerate and confine cosmic rays efficiently, satisfy both spectral and tomographic constraints. Introduction.-The discovery of the PeV neutrinos by IceCube [1,2] has launched the era of high-energy neutrino astronomy. The current data set is compatible with a flux in excess with respect to the atmospheric background, with an isotropic allocation of events on the celestial sphere and flavor equipartition [1][2][3][4][5][6]. Because of the current low statistics, the origin of the high-energy IceCube events is not yet known, but an extragalactic and mostly diffuse origin appears to be favored [7,8].High-energy neutrino production from cosmic accelerators has been the subject of a cascade of theoretical studies, especially after the IceCube results were announced [7,8]. Many papers discuss the neutrino emission from one specific source class by adopting a modeldependent approach, for active galactic nuclei (AGNs) [9][10][11][12][13][14][15][16][17][18], star-forming galaxies [19][20][21][22][23][24][25][26][27][28], gamma-ray bursts [29][30][31][32][33][34][35][36], galaxy clusters [37][38][39][40], and dark matter decays [41][42][43][44][45].Alternatively, a more generic approach focuses on the phenomenological aspects of the potential sources. For example, assuming photomeson production (pγ) of neutrinos, Ref.[46] obtained constraints on the source size and magnetic field strength needed to match the IceCube flux. Reference [47] hypothesized that the TeV-PeV neutrinos were generated via hadronuclear interactions (pp) and concluded that the cosmic ray spectrum of the dominant neutrino sources should be harder than E −2.2 . This is because the associated gamma-ray spectrum will extend down to GeV energies, where the flux of the isotropic gamma-ray background (IGRB) measured with the Fermi Large Area Telescope (LAT) [48] cannot be overshot. The connection with sources of ultrahigh-energy cosmic rays has also been considered [49][50][51].

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“…For instance, Waxman and Bahcall(1999) predicted a cosmic neutrino flux proportional to E −2.0 , according to the standard Fermi acceleration mechanism at shock fronts (Fermi 1949 g have suggested the presence of an additional component dominating at lower energies (E ν 200 TeV), on top of a single unbroken power-law flux (see Chen et al 2015;Vincent et al 2016;Anchordoqui et al 2017;see Kopper 2016 for studies of a neutrino flux with two power-laws and Kimura et al 2015;Murase et al 2016;Senno et al 2016 for viable hidden astrophysical candidates). The two-component scenario is also strongly motivated by the analyses performed on the up-going muon neutrinos (Aartsen et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Use of ANTARES and IceCube Data to Constrain a Single Power-law Neutrino Flux

Chianese

Mele

Miele

et al. 2017

ApJ

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We perform the first statistical combined analysis of the diffuse neutrino flux observed by ANTARES (nine-year) and IceCube (six-year) by assuming a single astrophysical power-law flux. The combined analysis reduces by a few percent the best-fit values for the flux normalization and the spectral index. Both data samples show an excess in the same energy range (40-200 TeV), suggesting the presence of a second component. We perform a goodnessof-fit test to scrutinize the null assumption of a single power-law, scanning different values for the spectral index. The addition of the ANTARES data reduces the p-value by a factor 2 3 . In particular, a single power-law component in the neutrino flux with the spectral index deduced by the six-year up-going muon neutrinos of IceCube is disfavored with a p-value smaller than 10 −2 .

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Neutrino and Cosmic-Ray Emission and Cumulative Background From Radiatively Inefficient Accretion Flows in Low-Luminosity Active Galactic Nuclei

Cited by 136 publications

References 101 publications

Stochastic Particle Acceleration in Turbulence Generated by Magnetorotational Instability

Stochastic Particle Acceleration in Turbulence Generated by Magnetorotational Instability

Tomographic Constraints on High-Energy Neutrinos of Hadronuclear Origin

Use of ANTARES and IceCube Data to Constrain a Single Power-law Neutrino Flux

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