On the Effect of Chaotic Orbits on Dynamical Friction

Cora, S. A.; Vergne, M. M.; Muzzio, J. C.

doi:10.1086/318223

Cited by 7 publications

(7 citation statements)

References 36 publications

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“…The parameter space of such configurations is considerably larger (and the freedom in cluster orbital projections smaller), potentially allowing more solutions to the timing problem. However, previous studies suggest that, while dynamical friction is on average stronger on box orbits than on loop orbits(Capuzzo-Dolcetta & Vicari 2005), triaxiality has no sifnificant overall effect on the strength of dynamical friction (Cora, Vergne & Muzzio 2001;Sachania 2009). This can be understood as cancellation of two opposing effects.…”

Section: Caveatsmentioning

confidence: 95%

The mass distribution of the Fornax dSph: constraints from its globular cluster distribution

Cole¹,

Dehnen²,

Read

et al. 2012

Monthly Notices of the Royal Astronomical Society

120

181

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Uniquely among the dwarf spheroidal (dSph) satellite galaxies of the Milky Way, Fornax hosts globular clusters. It remains a puzzle as to why dynamical friction has not yet dragged any of Fornax's five globular clusters to the centre, and also why there is no evidence that any similar star cluster has been in the past (for Fornax or any other tidally undisrupted dSph). We set up a suite of 2800 N‐body simulations that sample the full range of globular cluster orbits and mass models consistent with all existing observational constraints for Fornax. In agreement with previous work, we find that if Fornax has a large dark matter core, then its globular clusters remain close to their currently observed locations for long times. Furthermore, we find previously unreported behaviour for clusters that start inside the core region. These are pushed out of the core and gain orbital energy, a process we call ‘dynamical buoyancy’. Thus, a cored mass distribution in Fornax will naturally lead to a shell‐like globular cluster distribution near the core radius, independent of the initial conditions. By contrast, cold dark matter‐type cusped mass distributions lead to the rapid infall of at least one cluster within Δt = 1–2 Gyr, except when picking unlikely initial conditions for the cluster orbits (∼2 per cent probability), and almost all clusters within Δt = 10 Gyr. Alternatively, if Fornax has only a weakly cusped mass distribution, then dynamical friction is much reduced. While over Δt = 10 Gyr this still leads to the infall of one to four clusters from their present orbits, the infall of any cluster within Δt = 1–2 Gyr is much less likely (with probability 0–70 per cent, depending on Δt and the strength of the cusp). Such a solution to the timing problem requires (in addition to a shallow dark matter cusp) that in the past the globular clusters were somewhat further from Fornax than today; they most likely did not form within Fornax, but were accreted.

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Section: Caveatsmentioning

confidence: 95%

The mass distribution of the Fornax dSph: constraints from its globular cluster distribution

Cole¹,

Dehnen²,

Read

et al. 2012

Monthly Notices of the Royal Astronomical Society

120

181

View full text Add to dashboard Cite

show abstract

“…The results obtained by means of the perfect ellipsoid model (whose orbital properties have been fully studied by de Zeeuw 1985) constitute a deep analysis of the behaviour of regular orbits in triaxial potentials and give, also, results of astrophysical interest for elliptical galaxies with a central density core. Actually, even if in the cuspy models chaotic (irregular) orbits are in a relevant fraction (Gerhard & Binney 1985;Merritt & Fridman 1996;Merritt & Valluri 1996), some results seem to indicate that their presence does not affect significantly the orbital decay of the satellite (Cora, Vergne & Muzzio 2001). The self-consistent problem of the 'perfect ellipsoid' has been numerically solved by Statler (1987), who found a solution for the entire explored range of axis ratios, suggesting its existence for any axis ratio.…”

Section: The Galactic Modelsmentioning

confidence: 99%

Dynamical friction on globular clusters in core-triaxial galaxies: is it a cause of massive black hole accretion?

Capuzzo–Dolcetta¹,

Vicari²

2005

Monthly Notices of the Royal Astronomical Society

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The present work extends and deepens previous examinations of the evolution of globular cluster orbits in elliptical galaxies, by means of numerical integrations of a wide set of orbits in five self-consistent triaxial galactic models characterized by a central core and different axial ratios. These models are valid and complete in the representation of regular orbits in elliptical galaxies. Dynamical friction is definitely shown to be an efficient cause of evolution for the globular cluster systems in elliptical galaxies of any mass or axial ratio. Moreover, our statistically significant sample of computed orbits confirms that the globular cluster orbital decay times are, at least for clusters moving on box orbits, much shorter than the age of the galaxies. Consequently, the mass carried into the innermost galactic region in the form of decayed globular clusters may have contributed significantly to feeding and accreting a compact object therein

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“…The issue of the contrast between "local" and "non-local" effects has been rediscussed (Prugniel & Combes 1992;Maoz 1993;Cora, Muzzio & Vergne 1997), with the confirmation that the description of the friction process in terms of the "homogeneous limit" (Chandrasekhar 1943) should be adequate in the limit of low-mass, relatively compact satellites. A very recent investigation (Cora, Vergne & Muzzio 2001) also suggests that the process depends very little on the regularity or the stochasticity of the stellar orbits in the galaxy, in contrast with some earlier conjectures (Pfenniger 1986). Other interesting problems are the problem of circularization (of the satellite orbit), the relation of the friction effect to the past history of the dynamical event under consideration, and the issue of a direct calculation of the relevant dissipative force from the response of the stellar system to the perturbing satellite (e.g., see Séguin & Dupraz 1994, 1996 see also Colpi 1998;Colpi & Pallavicini 1998;Colpi, Mayer & Governato 1999;Nelson & Tremaine 1999).…”

Section: Introductionmentioning

confidence: 81%

Slow evolution of elliptical galaxies induced by dynamical friction

Bertin¹,

Лисейкина²,

Пегораро³

2003

A&A

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Abstract. The main goal of this paper is to set up a numerical simulation for the study of the slow evolution of the density and of the pressure tensor profiles of an otherwise collisionless stellar system, as a result of the interactions with a minority component of heavier "particles". The effects that we would like to study are those attributed to slow collisional relaxation and generically called "dynamical friction"; in real cases, or in numerical simulations, the processes involved are complex, so that the relaxation associated with the granularity in phase space is generally mixed with and masked by evolution resulting from lack of equilibrium or from a variety of instabilities and collective processes. We start by revisiting the problem of the sinking of a satellite inside an initially isotropic, non-rotating, spherical galaxy, which we follow by means of N-body simulations using about one million particles. We then consider a quasi-spherical problem, in which the satellite is fragmented into a set of many smaller masses with a spherically symmetric initial density distribution. In a wide set of experiments, designed in order to bring out effects genuinely associated with dynamical friction, we are able to demonstrate the slow evolution of the density profile and the development of a tangentially biased pressure in the underlying stellar system, while we briefly address the issue of the circularization of orbits induced by dynamical friction on the population of fragments. The results of the simulations presented here and others planned for future investigations allow us to study the basic mechanisms of slow relaxation in stellar systems and thus may be of general interest for a variety of problems, especially in the cosmological context. Here our experiments are conceived with the specific goal to clarify some mechanisms that may play a role in the evolution of an elliptical galaxy as a result of the interaction between the stars and a significant population of globular clusters or of the merging of a large number of small satellites.

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On the Effect of Chaotic Orbits on Dynamical Friction

Cited by 7 publications

References 36 publications

The mass distribution of the Fornax dSph: constraints from its globular cluster distribution

The mass distribution of the Fornax dSph: constraints from its globular cluster distribution

Dynamical friction on globular clusters in core-triaxial galaxies: is it a cause of massive black hole accretion?

Slow evolution of elliptical galaxies induced by dynamical friction

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