The Role of Ordered and Chaotic Motion in N-Body Models of Elliptical Galaxies Models

Voglis, N.; Kalapotharakos, Constantinos

doi:10.1007/1-4020-4348-1_9

Cited by 2 publications

(4 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Chaotic diffusion is important for producing secular evolution provided that the corresponding chaotic mass has initially an anisotropic spatial distribution. A more detailed examination of this effect is given in Voglis and Kalapotharakos (2005).…”

Section: Time Evolution and Self-organization Of The CM Modelmentioning

confidence: 98%

“…This field of research is very active in recent years (e.g. Merritt and Fridman, 1996;Merritt and Valluri, 1996;Fridman and Merritt, 1997;Valluri and Merritt, 1988;Merritt and Quinlan, 1998;Siopis, 1999;Siopis and Kandrup, 2000;Kandrup and Sideris, 2002;Merritt, 2002, 2004;Kandrup and Siopis, 2003;Kalapotharakos et al 2004;Voglis and Kalapotharakos, 2005) In order to investigate further this problem, we concentrate our study on a comparison between the following two models:…”

mentioning

confidence: 99%

See 1 more Smart Citation

Global Dynamics in Self-Consistent Models of Elliptical Galaxies

Kalapotharakos

Voglis

2005

Celestial Mech Dyn Astr

Self Cite

View full text Add to dashboard Cite

We compare two different N-body models simulating elliptical galaxies. Namely, the first model is a non-rotating triaxial N-body equilibrium model with smooth center, called SC model. The second model, called CM model, is derived from the SC by inserting a central mass in it, so that all possible differences between the two models are due to the effect of the central mass. The central mass is assumed to be mainly due to a massive central black hole of mass about 1% of the total mass of the galaxy. By using the fundamental frequency analysis, the two systems are thoroughly investigated as regards the types of orbits described either by test particles, or by the real particles of the systems at all the energy levels. A comparison between the orbits of test particles and the orbits of real particles at various energy levels is made on the rotation number plane. We find that extensive stable regions of phase space, detected by test particles remain empty, i.e. these regions are not occupied by real particles, while many real particles move in unstable regions of phase space describing chaotic orbits. We run self-consistently the two models for more than a Hubble time. During this run, in spite of the noise due to small variations of the potential, the SC model maintains (within a small uncertainly) the number of particles moving on orbits of each particular type. In contrast, the CM model is unstable, due to the large amount of mass in chaotic motion caused by the central mass. This system undergoes a secular evolution towards an equilibrium state. During this evolution it is gradually self-organized by converting chaotic orbits to ordered orbits mainly of the short axis tube type approaching an oblate spheroidal equilibrium. This is clearly demonstrated in terms of the fundamental frequencies of the orbits on the rotation number plane and the time evolution of the triaxiality index.

show abstract

Section: Time Evolution and Self-organization Of The CM Modelmentioning

confidence: 98%

mentioning

confidence: 99%

Global Dynamics in Self-Consistent Models of Elliptical Galaxies

Kalapotharakos

Voglis

2005

Celestial Mech Dyn Astr

Self Cite

View full text Add to dashboard Cite

show abstract

“…non-mixed distribution of the chaotic orbits caused by the fact that, before the insertion of the CMC, these were mostly regular orbits (boxes) of the original system. Voglis and Kalapotharakos (2006) found that the mean rate of exponential divergence (or mean level of LCN) of this chaotic component has a narrow correlation with m, scaling as m 1/2 . Furthermore, in order to measure the effectiveness of chaotic diffusion, these authors defined a parameter called 'effective diffusion momentum' L as the product of the anisotropically distributed chaotic mass times the mean logarithmic divergence of the orbits of this mass.…”

Section: Mcmc M Galaxymentioning

confidence: 96%

“…The exact evolution rate of the systems with CMCs depends mainly on two factors. a) the fraction of non-mixed chaotic orbits and b) the mean Lyapunov number of these orbits (Voglis and Kalapotharakos 2006). For example, the C-system with m = 0.01 needs longer time than the Q-system with the same m in order to evolve towards the final oblate configuration (Fig.35).…”

Section: Mcmc M Galaxymentioning

confidence: 99%