Power-law energy spectrum and orbital stochasticity

Mima, K.; Horton, W.; Tajima, T.; Hasegawa, Akira

doi:10.1063/1.40775

Cited by 8 publications

(3 citation statements)

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“…The accelerated electrons emit radiation from radio to high energy gammarays via synchrotron radiation and inverse Compton emission mechanism. The distribution of accelerated non-thermal particles becomes power law with a power law index ∼ −2 (Mima et al 1991), which is consistent with the observed blazar spectrum with the power law index close to −2. The photon index becomes close to −2, when the light curve of gamma-rays becomes active phase (Abdo et al 2010a(Abdo et al , 2011Britto et al 2016).…”

Section: Gamma-rayssupporting

confidence: 89%

Production of intense episodic Alfvén pulses: GRMHD simulation of black hole accretion discs

Mizuta

Ebisuzaki

Tajima

et al. 2018

Monthly Notices of the Royal Astronomical Society

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The episodic dynamics of the magnetic eruption of a spinning black hole (BH) accretion disks and its associated intense shapeup of their jets is studied via three-dimensional general-relativistic magnetohydrodynamics (GRMHD). The embedded magnetic fields in the disk get amplified by the magnetorotational instability (MRI) so large as to cause an eruption of magnetic field (recconection) and large chunks of matter episodically accrete toward the roots of the jets upon such an event. We also find that the eruption events produce intensive Alfvén pulses, which propagate through the jets. After the eruption, the disk backs to the weakly magnetic states. Such disk activities cause short time variabilities in mass accretion rate at the event horizon as well as electromagnetic luminosity inside the jet. Since the dimensionless strength parameter a 0 = eE/m e ωc of these Alfvén wave pulses is extremely high for a substantial fraction of Eddington accretion rate accretion flow onto a supermassive black hole, the Alfvén shocks turn into ultrarelativistic (a 0 ≫ 1) bow wake acceleration, manifesting into the ultra-high energy cosmic rays and electrons which finally emit gamma-rays. Since our GRMHD model has universality in its spatial and temporal scales, it is applicable to a wide range of astrophysical objects ranging from those of AGN (which is the primary target of this research), to micro-quasars. Properties such as time variabilities of blazar gamma-ray flares and spectrum observed by Fermi Gamma-ray Observatory are well explained by linear acceleration of electrons by the bow wake.

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Section: Gamma-rayssupporting

confidence: 89%

Production of intense episodic Alfvén pulses: GRMHD simulation of black hole accretion discs

Mizuta

Ebisuzaki

Tajima

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…We note that the spectral index from WFA is also close to 2 ( (Mima et al 1991); similar to that from Fermi mechanism), though we find the spectral index could vary, such as greater than 2 (see Figure. 9 and Canac et al (2020)).…”

Section: Discussionsupporting

confidence: 71%

DETECTION OF GAMMA-RAY EMISSION FROM THE STARBURST GALAXIES M82 AND NGC 253 WITH THE LARGE AREA TELESCOPE ON FERMI

Abdo¹,

Ackermann²,

Ajello³

et al. 2010

ApJ

195

128

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We present six case studies from a broad mass range (1 − 10 9 M) of astrophysical objects, each of which exhibit signs of jets and emit intense high energy gamma rays (> 10 GeV). Many of these objects also emit spatially identifiable ultra high energy cosmic rays (UHECRs). In all cases it is found that wakefield acceleration (WFA) explains both the global properties and details. For blazars, we also explain the temporal structure of these signals, which includes neutrinos, and the correlations in their "bursts" and anti-correlation in flux and index. Blazars (∼ 10 9 M), radio galaxies (∼ 10 8 M), Seyfert galaxies (∼ 10 6 M), starburst galaxies (∼ 10 3 M), down to microquasars (1 ∼ 10 M) interestingly exhibit the same physics since the nature of the accretion and acceleration is independent of the mass, aside from maximum values. It is possible to accelerate electrons to energies much greater than 10 GeV, and protons beyond 10 20 eV with WFA. We compare observational values with theoretical ones to illustrate they are in good agreement. This mechanism is also accompanied by related emissions, such as high-energy pinpointed neutrinos, time varying radio, optical, and X-ray emissions, opening an opportunity to characterize these astrophysical objects via multi-messenger approaches.

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“…The stochastic process of the random acceleration-deceleration can be described by the distribution function f ( , t) governed by the ChapmanKolmogorov equation 17,18 …”

Section: Maximum Energy Gain and Spectrummentioning

confidence: 99%

Cosmic Plasma Wakefield Acceleration

Chen¹,

Tajima²,

Takahashi³

2004

Quantum Aspects of Beam Physics 2003

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Recently we proposed a new cosmic acceleration mechanism 1 which was based on the wakefields excited by the Alfven shocks in a relativistically flowing plasma. In this paper we include some omitted details, and show that there exists a threshold condition for transparency below which the accelerating particle is collision-free and suffers little energy loss in the plasma medium. The stochastic encounters of the random accelerating-decelerating phases results in a power-law energy spectrum: f ( ) ∝ 1/ 2 . As an example, we discuss the possible production of super-GZK ultra high energy cosmic rays (UHECR) in the atmosphere of gamma ray bursts. The estimated event rate in our model agrees with that from UHECR observations.

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Power-law energy spectrum and orbital stochasticity

Cited by 8 publications

References 0 publications

Production of intense episodic Alfvén pulses: GRMHD simulation of black hole accretion discs

Production of intense episodic Alfvén pulses: GRMHD simulation of black hole accretion discs

DETECTION OF GAMMA-RAY EMISSION FROM THE STARBURST GALAXIES M82 AND NGC 253 WITH THE LARGE AREA TELESCOPE ON FERMI

Cosmic Plasma Wakefield Acceleration

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