Long-range correlations in self-gravitating<i>N</i>-body systems

Huber, Daniel; Pfenniger, D.

doi:10.1051/0004-6361:20020232

Cited by 20 publications

(13 citation statements)

References 49 publications

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“…It can also heat the gas (Thomasson, Donner & Elmegreen 1991;Bertin & Lodato 2001;Gammie 2001) and feed turbulence (Huber & Pfenniger 2001;Wada, Meurer & Norman 2002). Continued collapse of the gas may feed more turbulence on smaller scales (Semelin et al 1999, Chavanis 2002, Huber & Pfenniger 2002. A gravitational source of turbulence is consistent with the observed power spectra of flocculent spiral arms (Elmegreen et al 2003).…”

Section: Power Sources For Interstellar Turbulencementioning

confidence: 54%

Interstellar Turbulence I: Observations and Processes

Elmegreen

Scalo

2004

Annu. Rev. Astron. Astrophys.

1,102

983

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Turbulence affects the structure and motions of nearly all temperature and density regimes in the interstellar gas. This two-part review summarizes the observations, theory, and simulations of interstellar turbulence and their implications for many fields of astrophysics. The first part begins with diagnostics for turbulence that have been applied to the cool interstellar medium, and highlights their main results. The energy sources for interstellar turbulence are then summarized along with numerical estimates for their power input. Supernovae and superbubbles dominate the total power, but many other sources spanning a large range of scales, from swing amplified gravitational instabilities to cosmic ray streaming, all contribute in some way. Turbulence theory is considered in detail, including the basic fluid equations, solenoidal and compressible modes, global inviscid quadratic invariants, scaling arguments for the power spectrum, phenomenological models for the scaling of higher order structure functions, the direction and locality of energy transfer and cascade, velocity probability distributions, and turbulent pressure. We emphasize expected differences between incompressible and compressible turbulence. Theories of magnetic turbulence on scales smaller than the collision mean free path are included, as are theories of magnetohydrodynamic turbulence and their various proposals for power spectra. Numerical simulations of interstellar turbulence are reviewed. Models have reproduced the basic features of the observed scaling relations, predicted fast decay rates for supersonic MHD turbulence, and derived probability distribution functions for density. Thermal instabilities and thermal phases have a new interpretation in a supersonically turbulent medium. Large-scale models with various combinations of self-gravity, magnetic fields, supernovae, and -2 -star formation are beginning to resemble the observed interstellar medium in morphology and statistical properties. The role of self-gravity in turbulent gas evolution is clarified, leading to new paradigms for the formation of star clusters, the stellar mass function, the origin of stellar rotation and binary stars, and the effects of magnetic fields. The review ends with a reflection on the progress that has been made in our understanding of the interstellar medium, and offers a list of outstanding problems.

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Section: Power Sources For Interstellar Turbulencementioning

confidence: 54%

Interstellar Turbulence I: Observations and Processes

Elmegreen

Scalo

2004

Annu. Rev. Astron. Astrophys.

1,102

983

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“…This problem of incomplete relaxation must be approached with extensive numerical simulations. Of course, this program was started long ago (e.g., van Albada 1982) but only recently are N-body simulations carefully compared with the predictions of the statistical mechanics approach (Cerruti-Sola et al 2001;Huber & Pfenniger 2002) with variable success.…”

Section: Introductionmentioning

confidence: 99%

Gravitational instability of slowly rotating isothermal spheres

Chavanis

2002

A&A

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Abstract. We discuss the statistical mechanics of rotating self-gravitating systems by allowing properly for the conservation of angular momentum. We study analytically the case of slowly rotating isothermal spheres by expanding the solutions of the Boltzmann-Poisson equation in a series of Legendre polynomials, adapting the procedure introduced by Chandrasekhar (1933) for distorted polytropes. We show how the classical spiral of Lynden-Bell & Wood (1967) in the temperature-energy plane is deformed by rotation. We find that gravitational instability occurs sooner in the microcanonical ensemble and later in the canonical ensemble. According to standard turning point arguments, the onset of the collapse coincides with the minimum energy or minimum temperature state in the series of equilibria. Interestingly, it happens to be close to the point of maximum flattening. We generalize the singular isothermal solution to the case of a slowly rotating configuration. We also consider slowly rotating configurations of the self-gravitating Fermi gas at non-zero temperature.

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“…Subsequently, many researchers, e.g., Lecar [13], Standish [14], Gurzadyan et al [15], Kandrup [16], have investigated self-gravitating systems from the viewpoint of instability [17][18][19][20][21][22][23][24][25][26][27][28][29]. The instability discussed by them is the instability of a dynamical system in chaos theory, e.g., a separation rate of the distance between two nearby trajectories in phase space.…”

Section: Introductionmentioning

confidence: 99%