Runaway instability in accretion disks orbiting black holes

Abramowicz, Marek A.; Calvani, M.; Nobili, L.

doi:10.1038/302597a0

Cited by 118 publications

(108 citation statements)

References 13 publications

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“…In the actual numerical implementation, we do not use the inverse cosine to calculate the angles, as the function becomes very inaccurate when the vectors become close to being parallel or anti-parallel, instead we use the atan2 function which is free of this deficiency. The tilt ν(r) is then calculated using the following formula: (12) where the hat indicates unit vectors. For the twist σ(r), we need to be more careful.…”

Section: Twist and Tilt Anglesmentioning

confidence: 99%

Numerical relativity simulations of thick accretion disks around tilted Kerr black holes

et al. 2016

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In this work we present 3D numerical relativity simulations of thick accretion disks around tilted Kerr black holes. We investigate the evolution of three different initial disk models with a range of initial black hole spin magnitudes and tilt angles. For all the disk-to-black hole mass ratios considered (0.044 − 0.16) we observe significant black hole precession and nutation during the evolution. This indicates that for such mass ratios, neglecting the self-gravity of the disks by evolving them in a fixed background black hole spacetime is not justified. We find that the two more massive models are unstable against the Papaloizou-Pringle (PP) instability and that those PP-unstable models remain unstable for all initial spins and tilt angles considered, showing that the development of the instability is a very robust feature of such PP-unstable disks. Our lightest model, which is the most astrophysically favorable outcome of mergers of binary compact objects, is stable. The tilt between the black hole spin and the disk is strongly modulated during the growth of the PP instability, causing a partial global realignment of black hole spin and disk angular momentum in the most massive model with constant specific angular momentum l. For the model with non-constant lprofile we observe a long-lived m = 1 non-axisymmetric structure which shows strong oscillations of the tilt angle in the inner regions of the disk. This effect might be connected to the development of Kozai-Lidov oscillations. Our simulations also confirm earlier findings that the development of the PP instability causes the long-term emission of large amplitude gravitational waves, predominantly for the l = m = 2 multipole mode. The imprint of the BH precession on the gravitational waves from tilted BH-torus systems remains an interesting open issue that would require significantly longer simulations than those presented in this work.

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Section: Twist and Tilt Anglesmentioning

confidence: 99%

Numerical relativity simulations of thick accretion disks around tilted Kerr black holes

et al. 2016

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“…If the potential well is increasingly filled, the torus will grow and deform until it overflows the inner Roche lobe and accretion onto the central mass begins. This Roche lobe is analogous to that which occurs in binary systems, except in this case it is an effect of General Relativity (Abramowicz, Calvani & Nobili 1983), specifically of the existence of capture orbits for a finite value of angular momentum (see Figure 1).…”

Section: Figmentioning

confidence: 70%

Forced oscillations in fluid tori and quasi‐periodic oscillations

Lee¹

2005

Astron Nachr

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Abstract. The kilo-Hertz Quasi-Periodic Oscillations in X-ray binaries could originate within the accretion flow, and be a signature of non-linear fluid oscillations and mode coupling in strong gravity. The possibility to decipher these systems will impact our knowledge of fundamental parameters such as the neutron star mass, radius, and spin. Thus they offer the possibility to constrain the nuclear equation of state and the rotation parameter of stellar-mass black holes. We review the general properties of these oscillations from a hydrodynamical point of view, when the accretion flow is subject to external perturbations and summarize recent results.

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“…Several factors need to be considered, we address each in turn. The "runaway radial" instability discovered by Abramowicz et al [312] applies to configurations with constant specific angular momentum as a function of radius. This is fully an effect of General Relativity, dependent on the existence of an inner Roche lobe for disk accretion, akin to the L 1 Lagrange point in binary stellar evolution.…”

Section: Stability and Convectionmentioning

confidence: 98%

The Progenitors of Short Gamma-Ray Bursts

Ramírez-Ruiz¹

2006

AIP Conference Proceedings

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Abstract. Recent months have witnessed dramatic progress in our understanding of short γ-ray burst (SGRB) sources. There is now general agreement that SGRBs -or at least a substantial subset of them -are capable of producing directed outflows of relativistic matter with a kinetic luminosity exceeding by many millions that of active galactic nuclei. Given the twin requirements of energy and compactness, it is widely believed that SGRB activity is ultimately ascribable to a modest fraction of a solar mass of gas accreting onto a stellar mass black hole or to a precursor stage whose inevitable end point is a stellar mass black hole. Astrophysical scenarios involving the violent birth of a rapidly rotating neutron star, or an accreting black hole in a merging compact binary driven by gravitational wave emission are reviewed, along with other possible alternatives (collisions or collapse of compact objects). If a black hole lies at the center of this activity, then the fundamental pathways through which mass, angular momentum and energy can flow around and away from it play a key role in understanding how these prime movers can form collimated, relativistic outflows. Flow patterns near black holes accreting matter in the hypercritical regime, where photons are unable to provide cooling, but neutrinos do so efficiently, are discussed in detail, and we believe that they offer the best hope of understanding the central engine. On the other hand, statistical investigations of SGRB niches also furnish valuable information on their nature and evolutionary behavior. The formation of particular kinds of progenitor sources appears to be correlated with environmental effects and cosmic epoch. In addition, there is now compelling evidence for the continuous fueling of SGRB sources. We suggest here that the observed late flaring activity could be due to a secondary accretion episode induced by the delayed fall back of material dynamically stripped from a compact object during a merger or collision. Some important unresolved questions are identified, along with the types of observation that would discriminate among the various models. Many of the observed properties can be understood as resulting from outflows driven by hyperaccreting black holes and subsequently collimated into a pair of anti-parallel jets. It is likely that most of the radiation we receive is reprocessed by matter quite distant to the black hole; SGRB jets, if powered by the hole itself, may therefore be one of the few observable consequences of how flows near nuclear density behave under the influence of strong gravitational fields.

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Runaway instability in accretion disks orbiting black holes

Cited by 118 publications

References 13 publications

Numerical relativity simulations of thick accretion disks around tilted Kerr black holes

Numerical relativity simulations of thick accretion disks around tilted Kerr black holes

Forced oscillations in fluid tori and quasi‐periodic oscillations

The Progenitors of Short Gamma-Ray Bursts

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