The realignment of a black hole misaligned with its accretion disc

Scheuer, P. A. G.; Feiler, R.

doi:10.1093/mnras/282.1.291

Cited by 181 publications

(343 citation statements)

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“…By standard arguments [7,10] it follows that the lines of acoustic propagation are null geodesics with respect to the acoustic metric. In other words, the wave vector k µ , which is timelike and may be normalized to unity, is null with respect to the acoustic metric, i.e., 28) and satisfies the acoustic geodesic equation…”

Section: Propagation Of Acoustic Perturbationsmentioning

confidence: 99%

Acoustic horizons in axially symmetric relativistic accretion

Abraham

Bilić

Das

2006

Class. Quantum Grav.

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Transonic accretion onto astrophysical objects is a unique example of analogue black hole realized in nature. In the framework of acoustic geometry we study axially symmetric accretion and wind of a rotating astrophysical black hole or of a neutron star assuming isentropic flow of a fluid described by a polytropic equation of state. In particular we analyze the causal structure of multitransonic configurations with two sonic points and a shock. Retarded and advanced null curves clearly demonstrate the presence of the acoustic black hole at regular sonic points and of the white hole at the shock. We calculate the analogue surface gravity and the Hawking temperature for the inner and outer acoustic horizons.

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Section: Propagation Of Acoustic Perturbationsmentioning

confidence: 99%

Acoustic horizons in axially symmetric relativistic accretion

Abraham

Bilić

Das

2006

Class. Quantum Grav.

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“…Under these assumptions, kicks with velocities larger than 500 km s −1 are relatively common (Figure 1 of 454 S. Komossa Komossa & Merritt 2008b). In gas-rich mergers, the SMBH spins may align with the orbital angular momentum (e.g., Scheuer & Feiler 1996;Natarajan & Armitage 1999;Bogdanović et al 2007;Perego et al 2009). The timescale of alignment, in comparison to the binary coalescence timescale, then determines the fraction of high-velocity kicks in gas-rich systems (another important factor is the amount of gas accretion before versus after the merger).…”

Section: The Frequency Of Recoiling Smbhsmentioning

confidence: 99%

Electromagnetic Signatures of Recoiling Black Holes

Komossa¹

2009

Proc. IAU

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Abstract. Recent numerical relativity simulations predict that coalescing supermassive black holes (SMBHs) can receive kick velocities up to several thousands of kilometers per second due to anisotropic emission of gravitational waves, leading to long-lived oscillations of the SMBHs in galaxy cores and even SMBH ejections from their host galaxies. Observationally, accreting recoiling SMBHs would appear as quasars spatially and/or kinematically offset from their host galaxies. The presence of these "kicks" and "superkicks" has a wide range of exciting astrophysical implications which only now are beginning to be explored, including consequences for black hole and galaxy growth at the epoch of structure formation, modes of feedback, unified models of AGN, and the number of obscured AGN. SMBH recoil oscillations beyond the torus scale can be on the order of a quasar lifetime, thus potentially affecting a large fraction of the quasar population. We discuss how this might explain the long-standing puzzle of a deficiency of obscured type 2 quasars at high luminosities. Observational signatures of recoiling SMBHs are discussed and results from follow-up studies of the candidate recoiling SMBH SDSSJ0927+2943 are presented.

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“…The resolution of this problem was the realization ) that the condition for co-or counter-alignment actually depends on the magnitudes of the disk and black hole angular momenta, and their initial orientation. Scheuer & Feiler's (1996) paper had implicitly assumed conditions allowing only co-alignment and spin-up. Using the analytic formula of King et al (2005) and assuming sufficiently small feeding events (e.g., limited by self-gravity) shows that most SMBH are likely to have low spins.…”

Section: Accretion: Disksmentioning

confidence: 99%

Accretion and Outflow in Active Galaxies

King

2009

Proc. IAU

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Abstract. I review accretion and outflow in active galactic nuclei. Accreti4on appears to occur in a series of very small-scale, chaotic events, whose gas flows have no correlation with the largescale structure of the galaxy or with each other. The accreting gas has extremely low specific angular momentum and probably represents only a small fraction of the gas involved in a galaxy merger, which may be the underlying driver.Eddington accretion episodes in AGN must be common in order for the supermassive black holes to grow. I show that they produce winds with velocities v ∼ 0.1c and ionization parameters implying the presence of resonance lines of helium-like and hydrogen-like iron. The wind creates a strong cooling shock as it interacts with the interstellar medium of the host galaxy, and this cooling region may be observable in an inverse Compton continuum and lower-excitation emission lines associated with lower velocities. The shell of matter swept up by the shocked wind stalls unless the black hole mass has reached the value M σ implied by the M -σ relation. Once this mass is reached, further black hole growth is prevented. If the shocked gas did not cool as asserted above, the resulting ("energy-driven") outflow would imply a far smaller SMBH mass than actually observed. Minor accretion events with small gas fractions can produce galaxy-wide outflows, including fossil outflows in galaxies where there is little current AGN activity.

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The realignment of a black hole misaligned with its accretion disc

Cited by 181 publications

References 0 publications

Acoustic horizons in axially symmetric relativistic accretion

Acoustic horizons in axially symmetric relativistic accretion

Electromagnetic Signatures of Recoiling Black Holes

Accretion and Outflow in Active Galaxies

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