Electron-positron cascade in magnetospheres of spinning black holes

Ford, Alexander L.; Keenan, Brett; Medvedev, Mikhail V.

doi:10.1103/physrevd.98.063016

Cited by 20 publications

(21 citation statements)

References 25 publications

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“…So far in the literature there are quite a few works on the gap physics; most of them employ steady state/electrostatic models (Beskin et al 1992;Hirotani & Okamoto 1998;Broderick & Tchekhovskoy 2015;Ptitsyna & Neronov 2016;Hirotani et al , 2017Ford et al 2018;Levinson & Segev 2017). However, the gap development and screening may be an intrinsically time dependent process (Broderick & Tchekhovskoy 2015;Levinson & Segev 2017), similar to the polar cap gap in pulsars (Timokhin & Arons 2013).…”

Section: Introductionmentioning

confidence: 99%

Physics of Pair Producing Gaps in Black Hole Magnetospheres

Chen

Yuan

Yang

2018

ApJL

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In some low-luminosity accreting supermassive black hole systems, the supply of plasma in the funnel region can be a problem. It is believed that a local region with an unscreened electric field can exist in the black hole magnetosphere, accelerating particles and producing high-energy gamma-rays that can create e ± pairs. We carry out time-dependent self-consistent 1D PIC simulations of this process, including inverse-Compton scattering and photon tracking. We find a highly time-dependent solution where a macroscopic gap opens quasi-periodically to create e ± pairs and high-energy radiation. If this gap is operating at the base of the jet in M87, we expect an intermittency on the order of a few r g /c, which coincides with the timescale of the observed TeV flares from the same object. For Sagittarius A * the gap electric field can potentially grow to change the global magnetospheric structure, which may explain the lack of a radio jet at the center of our galaxy.

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Section: Introductionmentioning

confidence: 99%

Physics of Pair Producing Gaps in Black Hole Magnetospheres

Chen

Yuan

Yang

2018

ApJL

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“…This ratio may be initially imprinted at the base of the jet -for example, by magnetospheric spark-gap discharges (e.g. Blandford & Znajek 1977;Beskin et al 1992;Ford et al 2018;Chen et al 2018;Crinquand et al 2020b) or by interaction between the nascent jet and the accretion flow (e.g. Ripperda et al 2020;Wong et al 2021) -but it may also be modified in situ as the jet propagates.…”

Section: Relevance To Fsrq Observationsmentioning

confidence: 99%

Pair-Regulated Klein-Nishina Relativistic Magnetic Reconnection with Applications to Blazars and Accreting Black Holes

Mehlhaff,

Werner,

Uzdensky

et al. 2021

Preprint

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Relativistic magnetic reconnection is a powerful agent through which magnetic energy can be tapped in astrophysics, energizing particles that then produce observed radiation. In some systems, the highest energy photons come from particles Comptonizing an ambient radiation bath supplied by an external source. If the emitting particle energies are high enough, this inverse Compton (IC) scattering enters the Klein-Nishina regime, which differs from the low-energy Thomson IC limit in two significant ways. First, radiative losses become inherently discrete, with particles delivering an order-unity fraction of their energies to single photons. Second, Comptonized photons may pair-produce with the ambient radiation, opening up another channel for radiative feedback on magnetic reconnection. We analytically study externally illuminated highly magnetized reconnecting systems for which both of these effects are important. We identify a universal (initial magnetization-independent) quasi-steady state in which gamma-rays emitted from the reconnection layer are absorbed in the upstream region, and the resulting hot pairs dominate the energy density of the inflow plasma. However, a true pair cascade is unlikely, and the number density of created pairs remains subdominant to that of the original plasma for a wide parameter range. Future particle-in-cell simulation studies may test various aspects. Pair-regulated Klein-Nishina reconnection may explain steep spectra (quiescent and flaring) from flat-spectrum radio quasars and black hole accretion disc coronae.

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“…In our scenarios, this photon field is provided by the emission of the RIAF 1 (see Section 3). We locate the inner gap boundary at zgap = 2rg (Ford et al 2018) and assume homogeneity along its extension. Then, we obtain iteratively h in each scenario by solving equations 7 and 8 imposing the gap closure condition MIC = 1 2 .…”

Section: Acceleration By the Black Hole Dynamo Mechanismmentioning

confidence: 99%

Cosmic rays from the nearby starburst galaxy NGC 253: the effect of a low-luminosity active galactic nucleus

Gutiérrez

Romero

Vieyro

2020

Monthly Notices of the Royal Astronomical Society

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NGC 253 is a nearby starburst galaxy in the Sculptor group located at a distance of ∼ 3.5 Mpc that has been suggested by some authors as a potential site for cosmic-ray acceleration up to ultra-high energies. Its nuclear region is heavily obscured by gas and dust, which prevents establishing whether or not the galaxy harbours a supermassive black hole coexisting with the starburst. Some sources have been proposed in the literature as candidates for an active nucleus. In this work, we aim at determining the implications that the presence of a supermassive black hole at the nucleus of NGC 253 might have on cosmic ray acceleration. With this aim, we model the accretion flow on to the putative active nucleus, and we evaluate the feasibility of particle acceleration by the black hole dynamo mechanism. As a by-product, we explore the potential contribution from non-thermal particles in the accretion flow to the highenergy emission of the galaxy. We found that in the three most plausible nucleus candidates, the emission of the accretion flow would inhibit the black hole dynamo mechanism. To rule out completely the influence that a putative nucleus in NGC 253 might have in cosmic-ray acceleration, a better clarification concerning the true nature of the nucleus is needed.

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Electron-positron cascade in magnetospheres of spinning black holes

Cited by 20 publications

References 25 publications

Physics of Pair Producing Gaps in Black Hole Magnetospheres

Physics of Pair Producing Gaps in Black Hole Magnetospheres

Pair-Regulated Klein-Nishina Relativistic Magnetic Reconnection with Applications to Blazars and Accreting Black Holes

Cosmic rays from the nearby starburst galaxy NGC 253: the effect of a low-luminosity active galactic nucleus

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