Numerical simulations of the accretion-ejection instability  in
magnetised accretion disks

Caunt, S. E.; Tagger, M.

doi:10.1051/0004-6361:20000535

Cited by 28 publications

(39 citation statements)

References 32 publications

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“…Indeed, in the presence of the m = 2 mode of the RWI at the inner edge of the disk we tend to have a dominating m = 2 mode of the AEI. These modes also tend to have a messier Fourier representation than for the AEI alone (see for example Caunt & Tagger 2001, for an example of the AEI alone).…”

Section: Numerical Simulation Results and Mode Spectrummentioning

confidence: 99%

“…This criterion is fulfilled in disks with "reasonable" density and magnetic field profiles. For the sake of completeness we present here the main properties of the AEI, as they have been discussed elsewhere (Tagger & Pellat 1999;Caunt & Tagger 2001;Varnière et al 2003;Rodriguez et al 2002;Mikles et al 2009) in association with the type C LFQPO.…”

Section: The Different Flavors Of the Accretion-ejection Instabilitymentioning

confidence: 97%

“…This frequency is consistent with the LFQPO frequency (Tagger & Pellat 1999). -Linear theory and nonlinear simulations (Caunt & Tagger 2001) show that the AEI forms a standing wave pattern that can saturate at a finite amplitude. It can thus account for the persistence of a QPO whose quality factor should be limited only by the slow evolution of the factors (radial profiles of rotation, density, temperature, magnetic fieldÉ) that fix its frequency and amplitude, or by nonlinear interaction between the modes when more than one is present.…”

Section: The Different Flavors Of the Accretion-ejection Instabilitymentioning

confidence: 99%

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A possible interpretation for the apparent differences in LFQPO types in microquasars

Varnière

Tagger

Rodríguez

2012

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Aims. In most microquasars, low-frequency quasi-periodic oscillations (LFQPO) have been classified into three types (A, B and C depending on the peak distribution in the power density spectra and the shape of the noise) but no explanation has been proposed yet. The accretion-ejection instability (AEI) was presented in 1999 as a possible explanation for the fast varying LFQPO that occur most often. Here we look at a possible generalization to explain the characteristics of the other two LFQPO types. Methods. It was recently shown that when the disk approaches its last stable orbit, the AEI is markedly affected by relativistic effects. We focus on the characteristics of the LFQPO that would result from the relativistic AEI and compare them with the different LFQPO types. Results. The effects of relativity on the AEI seem to be able to explain most of the characteristics of the three types of LFQPO within one formalism.

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Section: Numerical Simulation Results and Mode Spectrummentioning

confidence: 99%

Section: The Different Flavors Of the Accretion-ejection Instabilitymentioning

confidence: 97%

Section: The Different Flavors Of the Accretion-ejection Instabilitymentioning

confidence: 99%

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A possible interpretation for the apparent differences in LFQPO types in microquasars

Varnière

Tagger

Rodríguez

2012

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“…As in Tagger & Varniere (2006), we use the 2.5D MHD code first introduced by Caunt & Tagger (2001) to study the non-linear evolution of the AEI. The code, based on a Zeus-type scheme, is similar to those used for simulations of galactic spiral structures before full 3D simulations were possible; it describes an infinitely thin disk in vacuum.…”

Section: Numerical Setupmentioning

confidence: 99%

A microquasar classification from a disk instability perspective

Tagger

Rodríguez

2010

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Aims. The spectacular variability of microquasars has led to many efforts to classify their observed behaviors in a few states. The progress made in the understanding of the quasi-periodic oscillations observed in these objects now makes it possible to develop a new way of identifying order in their behavior, based on the theorized physical processes associated with these oscillations. This development will also help us to reunite microquasars in a single classification based on the physical processes at work and therefore independent of their specific properties (mass, variation timescale, outburst history, etc.). This classification is intended to be a tool to improve our understanding of microquasar behavior and not to replace phenomenological states. Methods. We start by considering three instabilities that can cause accretion in the disk. We compare the conditions for their development, and the quasi-periodic oscillations they can be expected to produce, with the spectral states in which these quasi-periodic oscillations are observed and sometimes coexist. Results. From the three instabilities that we proposed to explain the three states of GRS 1915+105 we actually found the theoretical existence of four states. We compared those four states with observations and also how those four states can be seen in a model-independent fashion. Those four state can be used to find an order in microquasar observations, based on the properties of the quasi-periodic oscillations and the physics of the associated instabilities.

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“…A 2D verification of the non-linear evolution of the AEI was done by Caunt & Tagger (2001). The code, although based on a Zeus-type grid, is similar to that used for galactic spirals.…”

Section: A Modulation Of the Disk Emissionmentioning

confidence: 99%