Efficient generation of jets from magnetically arrested accretion on a rapidly spinning black hole

Tchekhovskoy, Alexander; Narayan, Ramesh; McKinney, Jonathan C.

doi:10.1111/j.1745-3933.2011.01147.x

Cited by 1,052 publications

(1,305 citation statements)

References 42 publications

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“…This is not a coincidence, but the result of the catalyst role of the magnetic field amplified by the disk. When the magnetic energy density exceeds the energy density ∼ ρc 2 of the accreting matter in the vicinity of the last stable orbit, the accretion is halted and the magnetic energy decreases, as shown by numerical simulations 9,22 , and confirmed by recent observational evidence 10 .…”

mentioning

confidence: 54%

The power of relativistic jets is larger than the luminosity of their accretion disks

Ghisellini

Tavecchio

Maraschi

et al. 2014

Nature

422

521

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Theoretical models for the production of relativistic jets from active galactic nuclei predict that jet power arises from the spin and mass of the central black hole, as well as the magnetic field near the event horizon 1 . The physical mechanism mechanism underlying the contribution from the magnetic field is the torque exerted on the rotating black hole by the field amplified by the accreting material. If the squared magnetic field is proportional to the accretion rate, then there will be a correlation between jet power and accretion luminosity. There is evidence for such a correlation 2-8 , but inadequate knowledge of the accretion luminosity of the limited and inhomogeneous used samples prevented a firm conclusion. Here we report an analysis of archival observations of a sample of blazars (quasars whose jets point towards Earth) that overcomes previous limitations. We find a clear correlation between jet power as measured through the γ-ray luminosity, and accretion luminosity as measured by the broad emission lines, with the jet power dominating over the disk luminosity, in agreement with numerical simulations 9 . This implies that the magnetic field threading the black hole horizon reaches the maximum value sustainable by the accreting matter 10 .The jet power is predicted 1 to depend on (aMB) 2 , where a and M are respectively the spin and mass of the black hole and B is the magnetic field at its horizon. Seed magnetic fields are amplified by the accretion disk up to equipartition with the mass energy density ∼ ρc 2 of the matter accreting at the rateṀ . A greaterṀ implies a larger ρ, that can sustain a larger magnetic field, which in turn can tap a larger amount of the black hole rotational energy. The magnetic field is thus a catalyst for the process. Increasing the spin of the black hole shrinks the innermost stable orbit, increasing the accretion efficiency η (defined by η = L disk /Ṁc 2 ) (L disk accretion disk luminosity) to a maximum value 11 η = 0.3.We use a well designed sample of blazars that have been detected in the γ-ray band by the Fermi Large Area Telescope (LAT) that have been spectroscopically observed in the optical 12, 13 (see Methods). They have been classified as BL Lac objects or Flat Spectrum Radio Quasars (FSRQs) according if the rest frame equivalent width of their broad emission lines was greater (FSRQ) or smaller (BL Lacs) than 5Å (rest frame). The sample contains 229 FSRQs, and 475 BL Lacs. Of the latter, 209 have a spectroscopically measured redshift. We considered all FSRQs with enough multi-wavelength data to have a Spectral Energy Distribution (SED) that allows to establish the bolometric luminosity. The considered FSRQs amount to 191 objects. Instead, for BL Lacs, we consider only the 26 sources with detected broad emission lines. This makes them the low disk luminosity tail of of the full 1 blazar sample. This choice is dictated by our will to measure the accretion luminosity, together with the jet power. Through the visible broad emission lines we reconstruct, through a t...

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mentioning

confidence: 54%

The power of relativistic jets is larger than the luminosity of their accretion disks

Ghisellini

Tavecchio

Maraschi

et al. 2014

Nature

422

521

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“…Blandford & Znajek 1977;Meier 1999), jet power is tied to the spinning of black hole. Then, it is quite possible to have highly powered jet with small black hole mass if the black hole has a high spin (the maximum jet power is close to the Eddington luminosity or an efficiency of ∼140% of the accretion power from Tchekhovskoy et al (2011)). The other possibility is that black hole mass is not main factor for difference between Fermi blazars and non-Fermi blazars.…”

Section: The Basic Properties Of Fermi Blazarsmentioning

confidence: 99%

Basic properties of Fermi blazars and the ‘blazar sequence’

Xiong

Zhang

Bai

et al. 2015

Monthly Notices of the Royal Astronomical Society

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By statistically analyzing a large sample which includes blazars of Fermi detection (FBs) and non-Fermi detection (NFBs), we find that there are significant differences between FBs and NFBs for redshift, black hole mass, jet kinetic power from "cavity" power, broad-line luminosity, and ratio of core luminosity to absolute V-band magnitude (R v ), but not for ratio of radio core to extended flux (R c ) and Eddington ratio. Compared with NFBs, FBs have larger mean jet power, R c and R v while smaller mean redshift, black hole mass, broad-line luminosity. These results support that the beaming effect is main reason for differences between FBs and NFBs, and that FBs are likely to have a more powerful jet. For both Fermi and non-Fermi blazars, there are significant correlations between jet power and the accretion rate (traced by the broad-emission-lines luminosity), between jet power and black hole mass; for Fermi blazars, the black hole mass does not have significant influence on jet power while for non-Fermi blazars, both accretion rate and black hole mass have contributions to the jet power. Our results support the "blazar sequence" and show that synchrotron peak frequency (ν peak ) is associated with accretion rate but not with black hole mass.

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“…Our results can be compared to those of the MHD simulations on accretion disks (e.g., Igumenshchev et al 2003;Beckwith et al 2009;Penna et al 2010;Tchekhovskoy et al 2011;McKinney et al 2012;Narayan et al 2012). The magnetic pressure can dominate over the gas pressure in the inner region of the disk, and it becomes a magnetic arrested disk (Igumenshchev et al 2003).…”

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confidence: 99%

An Accretion Disk-Outflow Model for Hysteretic State Transition in X-Ray Binaries

Cao

2016

ApJ

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We suggest a model of the advection-dominated accretion flow (ADAF) with magnetically driven outflows to explain the hysteretic state transition observed in X-ray binaries (XRBs). The transition from a thin disk to an ADAF occurs when the mass accretion rate is below a critical value. The critical mass accretion rate for the ADAF can be estimated by equating the equilibration timescale to the accretion timescale of the ADAF, which is sensitive to its radial velocity. The radial velocity of thin disks is very small, which leads to the advection of the external field in thin disks becoming very inefficient. ADAFs are present in the low/hard states of XRBs, and their radial velocity is large compared with the thin disk. The external field can be dragged inward efficiently by the ADAF, so a strong large-scale magnetic field threading the ADAF can be formed, which may accelerate a fraction of gas in the ADAF into the outflows. Such outflows may carry away a large amount of angular momentum from the ADAF, which significantly increases the radial velocity of the ADAF. This leads to a high critical mass accretion rate, below which an ADAF with magnetic outflows can survive. Our calculations show that the critical luminosity of the ADAF with magnetic outflows can be one order of magnitude higher than that for a conventional ADAF, if the ratio of gas to magnetic pressure 4 b~in the disk. This can naturally explain the hysteretic state transition observed in XRBs.

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Efficient generation of jets from magnetically arrested accretion on a rapidly spinning black hole

Cited by 1,052 publications

References 42 publications

The power of relativistic jets is larger than the luminosity of their accretion disks

The power of relativistic jets is larger than the luminosity of their accretion disks

Basic properties of Fermi blazars and the ‘blazar sequence’

An Accretion Disk-Outflow Model for Hysteretic State Transition in X-Ray Binaries

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