On the Role of Fast Magnetic Reconnection in Accreting Black Hole Sources

Singh, Chandra B.; Pino, E. M. de Gouveia Dal; Kadowaki, L. H. S.

doi:10.1088/2041-8205/799/2/l20

Cited by 57 publications

(86 citation statements)

References 28 publications

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“…Second, the emission may be solely the result of processes intrinsic to the jet without any direct correlation with the central engine except for the energy input. The third potential possibility is if the γ-ray emission from NGC 1275 is non-boosted from the disk corona, a likely location of the jet launching region as argued in Kadowaki et al (2015) and Singh et al (2015), then, similar imprints propagating downstream the jet may be boosted by the jet bulk motion which, by virtue of Doppler beaming, also makes more regions to contribute to the emission, making the flux distribution lognormal. It should be noted that a Doppler boost (δ) of a few to ten can make the NGC 1275 flux (∝ δ 3 /distance 2 ) similar to the BL Lacs and FSRQs studied in this work, though the energetics and dynamics details may be different for each source.…”

Section: Discussionmentioning

confidence: 99%

“…However, on a completely different scale, the X-ray emission from the whole Solar surface shows similar behavior (Zhang 2007) where the variability is well understood to be a manifestation of magnetic reconnection process. Moreover, all accreting compact systems are believed to have magnetic fields of varying degree, making the uniqueness claim ambiguous (see, for instance, a possible magnetic reconnection scenario for flares from microquasars and non-blazar low luminous AGNs in de Gouveia dal Pino & Lazarian 2005;Kadowaki et al 2015;Khiali et al 2015;Singh et al 2015). In blazars, almost all the emission, on the other hand, is understood to be originating primarily in the jet as a result of the interaction of jet plasma and magnetic field.…”

Section: Introductionmentioning

confidence: 99%

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Gamma-Ray Flux Distribution and Nonlinear Behavior of Four LAT Bright AGNs

Kushwaha

Sinha

Misra

et al. 2017

ApJ

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We present a statistical characterization of the γ-ray emission from the four Fermi -LAT sources: FR I radio galaxy NGC 1275, BL Lac Mrk 421, FSRQs B2 1520+31 and PKS 1510-089 detected almost continuously over a time integration of 3-days between August 2008 -October 2015. The observed flux variation is large, spanning 2 orders of magnitude between the extremes except for Mrk 421. We compute the flux distributions and compare with Gaussian and lognormal ones. We find that the 3 blazars have distribution consistent with a lognormal, suggesting that the variability is of a non-linear, multiplicative nature. This is further supported by the computation of the flux-rms relation, which is observed to be linear for the 3 blazars. However, for NGC 1275, the distribution does not seem to be represented either by a lognormal or a Gaussian, while its flux-rms relation is still found to be linear. We also compute the power spectra, which suggest the presence of a break, but are consistent with typical scale-free power-law shot noise. The results are broadly consistent with the statistical properties of the magnetic reconnection powered minijets-in-a-jet model. We discuss other possible scenarios and implications of these observations on jet processes and connections with the central engine.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Gamma-Ray Flux Distribution and Nonlinear Behavior of Four LAT Bright AGNs

Kushwaha

Sinha

Misra

et al. 2017

ApJ

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“…(13). This is relevant for exploring reconnection events in the corona and jet launching regions of the black hole [21,[39][40][41][42][43].…”

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confidence: 99%

Relativistic Magnetic Reconnection in Kerr Spacetime

Asenjo

Comisso

2017

Phys. Rev. Lett.

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The magnetic reconnection process is analyzed for relativistic magnetohydrodynamical plasmas around rotating black holes. A simple generalization of the Sweet-Parker model is used as a first approximation to the problem. The reconnection rate, as well as other important properties of the reconnection layer, have been calculated taking into account the effect of spacetime curvature. Azimuthal and radial current sheet configurations in the equatorial plane of the black hole have been studied, and the case of small black hole rotation rate has been analyzed. For the azimuthal configuration, it is found that the black hole rotation decreases the reconnection rate. On the other hand, in the radial configuration, it is the gravitational force created by the black hole mass that decreases the reconnection rate. These results establish a fundamental interaction between gravity and magnetic reconnection in astrophysical contexts.Introduction.-The rapid conversion of magnetic energy into plasma particle energy through the process of magnetic reconnection is of paramount importance in many astrophysical processes [1]. Magnetospheric substorms, coronal mass ejections, stellar and gamma-ray flares are just a few examples of pheneomena in which magnetic reconnection is thought to play a crucial role.In recent years, significant work has been undertaken to better understand magnetic reconnection in magnetically dominated environments, where relativistic effects become significant [2]. This has led to the generalization of the classical Sweet-Parker and Petschek reconnection models to the special relativistic regime [3,4]. Furthermore, many numerical campaigns have been devoted to the investigation of the reconnection rate [5][6][7][8][9][10][11][12] and the particle acceleration [13][14][15][16][17][18][19][20] in this regime. Relativistic reconnection has been found to be a very efficient mechanism of magnetic energy conversion and particle acceleration, making it a primary candidate to explain nonthermal emissions from pulsar wind nebulae, gamma-ray bursts, and active galactic nuclei.While special relativistic effects on the reconnection process are starting to become clear, the effects related to the spacetime curvature are far less explored and a detailed understanding is lacking. General relativistic magnetohydrodynamic simulations have repeatedly shown the formation of reconnection layers in proximity of blacks holes [21][22][23][24], where spacetime curvature effects can be important. However, the difficulties related to the spatial and temporal resolution of typical reconnection processes have been such to prevent their thorough study.A step forward in the comprehension of magnetic reconnection in curved spacetime could be taken by studying simple generalizations of known theoretical models. It is the purpose of this Letter to develop such theoretical study considering the contribution of the gravitational

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“…The MDAF scenario naturally drives turbulence in the corona. The results by Singh et al (2015) again indicate that fast reconnection is relatively insensitive to the accretion disk model. The similarity between the results produced in their paper with MDAF accretion and those of Kadowaki et al (2015) with standard disk accretion is striking.…”

Section: Turbulent Mass Loadingmentioning

confidence: 78%

“…In our model, this energy generated by turbulent reconnection would be taken from the local tangled magnetic field and put into the initial acceleration of the disk wind until it will be further accelerated by the magneto-centrifugal mechanism. Singh et al (2015) investigate the role of fast magnetic reconnection in accreting black hole sources. Instead of assuming that the accretion disk has already evolved to a ShakuraSunyaev regime as the initial state as in previous works, they assume a magnetically dominated advective flow (MDAF) disk.…”

Section: Turbulent Mass Loadingmentioning

confidence: 99%

A new view on the M 87 jet origin: Turbulent loading leading to large-scale episodic wiggling

Britzen

Fendt

Eckart

et al. 2017

A&A

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Context. The nearby, giant radio galaxy M 87 hosts a supermassive black hole (BH) and is well-known for a bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large BH mass, M 87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. Many kinematic studies have been performed to determine the proper motions in the jet. Despite M 87 providing all proofs of being an active BH, the apparent jet speed remained puzzling, because proper motion measurements between 15 and 43 GHz for the same region of 1-10 mas core distance provided largely discrepant results. This source is a prime object to be studied in exquisite detail with the upcoming Event Horizon Telescope (EHT) observations because it promises to allow a direct view on the jet launching process itself. Aims. We aim to decipher some of the kinematic puzzles in the pc-scale jet with the analysis we present here. Methods. We re-modeled and re-analyzed 31 VLBA observations at 15 GHz obtained within the MOJAVE program. The data span a time range between Jul. 1995 and May 2011. We performed a detailed investigation of the pc-scale jet kinematics on different timescales, the shortest periods between the observations beeing 10 and 80 days, and in different jet modes, making use of VLBA observations. In addition, we studied the jet ridge line behavior as a function of time. Special care was taken to analyze the region close to the 15 GHz core, and the dynamics and distribution of newly emerging jet features in the jet. Results. We find an indication for apparent superluminal motion in the jet. Moreover, we present evidence for acceleration between 0.5 and 10 mas of core separation. The data suggest that the central part of M 87 at 15 GHz seems to be rotating. Jet components and counter-jet components are ejected in different directions under varying angles, explaining the impression of a broad opening angle. In this paper we present evidence for two different operating modes of the jet of M 87. The jet switches between two phases: i) the jet ridge line is at least double or the jet axis is displaced vertically, and ii) an unperturbed phase where the jet ridge line remains almost straight but is smoothly curved and the jet components are aligned along a classical jet axis. The mode change occurs every couple of years. Between the two operating modes, a transition phase is visible. Conclusions. The M 87 jet visible at 15 GHz probes a different physical zone compared to the standard blazar-zone we tend to see in AGN jets. The most likely scenario explaining the observed phenomena is a turbulent mass loading into the jet, most probably due to local, fast reconnection processes driven by turbulence of a tangled magnetic field, which is either generated in the accretion disk or the disk corona. In addition, on large scales, a global magnetic structure is required to channel the turbulent flow into what evolves into a large-scale jet. Large-scale...

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On the Role of Fast Magnetic Reconnection in Accreting Black Hole Sources

Cited by 57 publications

References 28 publications

Gamma-Ray Flux Distribution and Nonlinear Behavior of Four LAT Bright AGNs

Gamma-Ray Flux Distribution and Nonlinear Behavior of Four LAT Bright AGNs

Relativistic Magnetic Reconnection in Kerr Spacetime

A new view on the M 87 jet origin: Turbulent loading leading to large-scale episodic wiggling

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