Triaxial Black Hole Nuclei

Poon, M. Y.; Merritt, David

doi:10.1086/340395

Cited by 43 publications

(46 citation statements)

References 23 publications

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“…The compatibility of the presence of a massive central mass with a modest or a maximal triaxiality of the system is also supported by the results of Poon & Merritt (2002, 2004, who find that stable triaxial configuration in system with cuspy density profiles can exist.…”

Section: Effects Due To a Central Massmentioning

confidence: 62%

Chaos and secular evolution of triaxial N-body galactic models due to an imposed central mass

Kalapotharakos

Voglis

Contopoulos

2004

A&A

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Abstract.We investigate the response of triaxial non-rotating N-body models of elliptical galaxies with smooth centers, initially in equilibrium, under the presence of a central mass assumed to be due mainly to a massive central black hole. We examine the fraction of mass in chaotic motion and the resulting secular evolution of the models. Four cases of the size of the central mass are investigated, namely m = 0.0005, 0.0010, 0.0050, 0.0100 in units of the total mass of the galaxy. We find that a central mass with value m < 0.005 increases the mass fraction in chaotic motion from the level of 25−35% (that appears in the case of smooth centers) to the level of 50−80% depending on the value of m and on the initial maximum ellipticity of the system. However, most of this mass moves in chaotic orbits with Lyapunov numbers too small to develop chaotic diffusion in a Hubble time. Thus their secular evolution is so slow that it can be neglected in a Hubble time. Larger central masses (m > ∼ 0.005) give initially about the same fractions of mass in chaotic motion as for smaller m, but the Lyapunov numbers are concentrated to larger values, so that a secular evolution of the self-consistent models is prominent. These systems evolve in time tending to a new equilibrium. During their evolution they become self-organized by converting chaotic orbits to ordered orbits of the Short Axis Tube type. The mechanism of such a self-organization is investigated. The rate of this evolution depends on m and on the value of the initial maximum ellipticity of the system. For m = 0.01 and a large initial maximum ellipticity E max ≈ 7, equilibrium can be achieved in one Hubble time, forming an oblate spheroidal configuration. For the same value of m and initial maximum elipticity E max ≈ 3.5, or for E max ≈ 7, but m = 0.005, oblate equilibrium configurations can also be achieved, but in much longer times. Furthermore, we find that, for m = 0.005 and E max ≈ 3.5, triaxial equilibrium configurations can be formed. The fraction of mass in chaotic motion in the equilibrium configurations is in the range of 12−25%.

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Section: Effects Due To a Central Massmentioning

confidence: 62%

Chaos and secular evolution of triaxial N-body galactic models due to an imposed central mass

Kalapotharakos

Voglis

Contopoulos

2004

A&A

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“…It should be noted that there are dynamical mechanisms that may increase the tidal disruption rate beyond that predicted by two-body scattering in a spherical system. The possibilities include the effects of massive perturbers, for example giant molecular clouds (Zhao, Haehnelt & Rees 2002), which indeed exist in the GC on scales of 1-2 pc from the MBH; enhanced rates due to resonant scattering (factor of ∼2 rate increase; Rauch & Tremaine 1996;Rauch & Ingalls 1998); deviations from spherical symmetry (factor of ∼ 2 rate increase; Magorrian & Tremaine 1999); or chaotic orbits in triaxial potentials (factor of 10-100 rate increase; Poon & Merritt 2002;Merritt & Poon 2004). …”

Section: Tidal Disruption Ratementioning

confidence: 99%

Stellar processes near the massive black hole in the Galactic center

2005

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“…However, there will generally exist a subset of orbits defined by a maximum pericenter distance that is da, and stars on such orbits will interact with the binary once per crossing time, just as in the spherical case. As an example, consider centrophilic (chaotic) orbits in a triaxial nucleus (Poon & Merritt 2002). There is one such orbit per energy (in a time-averaged sense), and the cumulative distribution of pericenter distances for a single orbit is found to be linear in r p up to a maximum value, r p;max ðEÞ (Merritt & Poon 2003).…”

Section: Reejection In Other Geometriesmentioning

confidence: 99%

Long‐Term Evolution of Massive Black Hole Binaries

Milosavljević

Merritt

2003

ApJ

Self Cite

264

276

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The long-term evolution of massive black hole binaries at the centers of galaxies is studied in a variety of physical regimes, with the aim of resolving the '' final parsec problem,'' i.e., how black hole binaries manage to shrink to separations at which emission of gravity waves becomes efficient. A binary ejects stars by the gravitational slingshot and carves out a loss cone in the host galaxy. Continued decay of the binary requires a refilling of the loss cone. We show that the standard treatment of loss cone refilling, derived for collisionally relaxed systems like globular clusters, can substantially underestimate the refilling rates in galactic nuclei. We derive expressions for nonequilibrium loss cone dynamics and calculate timescales for the decay of massive black hole binaries following galaxy mergers, obtaining significantly higher decay rates than heretofore. Even in the absence of two-body relaxation, decay of binaries can persist as a result of repeated ejection of stars returning to the nucleus on eccentric orbits. We show that this recycling of stars leads to a gradual, approximately logarithmic dependence of the binary binding energy on time. We derive an expression for the loss cone refilling induced by the Brownian motion of a black hole binary. We also show that numerical N-body experiments are not well suited to probe these mechanisms over long times as a result of spurious relaxation.

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Triaxial Black Hole Nuclei

Cited by 43 publications

References 23 publications

Chaos and secular evolution of triaxial N-body galactic models due to an imposed central mass

Chaos and secular evolution of triaxial N-body galactic models due to an imposed central mass

Stellar processes near the massive black hole in the Galactic center

Long‐Term Evolution of Massive Black Hole Binaries

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