Magnetically Arrested Disk: an Energetically Efficient Accretion Flow

Narayan, Ramesh; Igumenshchev, I. V.; Abramowicz, Marek A.

doi:10.1093/pasj/55.6.l69

Cited by 642 publications

(576 citation statements)

References 28 publications

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“…They considered a model of jet formation from black hole (BH) spin-energy extraction (Blandford & Znajek 1977). Zdziarski et al (2015) considered models with the accretion being magnetically arrested (MAD; Narayan, Igumenshchev, & Abramowicz (2003)). Such flows have dragged so much magnetic flux to the BH that it becomes dynamically important owing to obstruction of accretion, and is given by ΦBH ≃ 50(Ṁ c) (Tchekhovskoy et al 2009),…”

Section: Application Of the Mad Modelmentioning

confidence: 99%

Core shift effect in blazars

Agarwal

Mohan

Gupta

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We studied the pc-scale core shift effect using radio light curves for three blazars, S5 0716+714, 3C 279 and BL Lacertae, which were monitored at five frequencies (ν) between 4.8 GHz and 36.8 GHz using the University of Michigan Radio Astronomical Observatory (UMRAO), the Crimean Astrophysical Observatory (CrAO), and Metsahovi Radio Observatory for over 40 years. Flares were Gaussian fitted to derive time delays between observed frequencies for each flare (∆t), peak amplitude (A), and their half width. Using A ∝ ν α we infer α in the range −16.67 to 2.41 and using ∆t ∝ ν 1/kr , we infer k r ∼ 1, employed in the context of equipartition between magnetic and kinetic energy density for parameter estimation. From the estimated core position offset (Ω rν ) and the core radius (r core ), we infer that opacity model may not be valid in all cases. The mean magnetic field strength at 1 pc (B 1 ) and at the core (B core ), are in agreement with previous estimates. We apply the magnetically arrested disk model to estimate black hole spins in the range 0.15 − 0.9 for these blazars, indicating that the model is consistent with expected accretion mode in such sources. The power law shaped power spectral density has slopes −1.3 to −2.3 and is interpreted in terms of multiple shocks or magnetic instabilities.

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Section: Application Of the Mad Modelmentioning

confidence: 99%

Core shift effect in blazars

Agarwal

Mohan

Gupta

et al. 2017

Monthly Notices of the Royal Astronomical Society

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“…Simulations demonstrate that a key role in determining such an efficient energy extraction is played by dynamically important magnetic fields built up in the inner regions of the accretion flow. In fact, the magnetic flux close to the BH horizon is so large that accretion likely occurs through a magnetically arrested accretion (MAD) flow (Narayan et al 2003, Tchekhovskoy et al 2011, McKinney et al 2012). …”

Section: Introductionmentioning

confidence: 99%

On the magnetization of BL Lac jets

Tavecchio¹,

Ghisellini²

2015

Mon. Not. R. Astron. Soc.

133

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“…However, in the magnetically arrested disk (MAD; Narayan et al 2003) scenario, black holes that are saturated with magnetic flux obey Q j = η MADṀ c 2 , with η MAD = 140% for a = 0.99 (Tchekhovskoy et al 2011).…”

Section: Introductionmentioning

confidence: 99%

The contribution of spin to jet-disk coupling in black holes

Velzen

Falcke

2013

A&A

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Context. The spin of supermassive black holes could power jets from active galactic nuclei (AGN), although direct observational evidence for this conjecture is sparse. The accretion disk luminosity and jet power, on the other hand, have long been observed to follow a linear correlation. Aims. If jet power is coupled to black hole spin, deviations from the jet-disk correlation for a sample of AGN can be used to probe the dispersion of the spin parameter (a) within this sample. Methods. To obtain a large sample of radio-loud AGN, we matched double-lobed radio sources identified in Faint Images of the Radio Sky at Twenty-centimeters (FIRST, 1.4 GHz) to spectroscopically confirmed quasars from the Sloan Digital Sky Survey (SDSS). We obtain 763 FR II quasars with a median redshift of z = 1.2. Results. A tight correlation between the optical luminosity of the accretion disk and the lobe radio luminosity is observed. We estimate that 5-20% of the bolometric disk luminosity is converted to jet power. Most of the scatter to the optical-radio correlation is due to environment; deviations from jet-disk coupling due to internal factors (e.g., spin) contribute at most 0.2 dex. Conclusions. Under the assumption that the Blandford-Znajek mechanism operates in AGN, we obtain an upper limit of 0.1 dex to the dispersion of the product of the spin and the magnetic flux threading the horizon. If black hole spin determines the AGN jet efficiency, then our observations imply that all FR II quasars have very similar spin. In addition, the quasar spin distribution needs to have a wide gap to explain the radio-quiet population. The alternative, and perhaps more likely, interpretation of the tight jet-disk correlation is that black hole spin is not relevant for powering AGN jets.

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Magnetically Arrested Disk: an Energetically Efficient Accretion Flow

Cited by 642 publications

References 28 publications

Core shift effect in blazars

Core shift effect in blazars

On the magnetization of BL Lac jets

The contribution of spin to jet-disk coupling in black holes

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