Tidal interaction between spherical galaxies

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1985

OSTI ID:5228092

Aguilar-Chiu, L A

The effects of tidal forces on the internal structure of nonrotating spherical galaxies that undergo a hyperbolic encounter are investigated using the impulse approximation and N-body experiments. The simulations use models with King and de Vaucouleurs surface-density profiles and radial, tangential, and isotropic velocity distributions. The impulse approximation, which holds when the internal timescale of the interacting galaxies are much longer than the encounter time, is found to give results in good agreement with the N-body simulations. The fractional change in binding energy and total mass does not have a simple power law dependence on the encounter parameters, as previously reported by other investigators, but rather a smooth intermediate behavior. The cross sections exhibit very little dependence on the internal orbital structure of the galaxy, but depend quite strongly on the shape of the surface-density profile in the outer parts. The use of rate equations to compute the mean change in mass and binding energy for a galaxy subject to encounters is very misleading; the encounter integrals are dominated by a few strong encounters, and not by the cumulative effect of many encounters. A stochastic approach should be adopted in order to model the evolution of a cluster adequately.

• Research Organization: California Univ., Berkeley (USA)
• OSTI ID: 5228092
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BASIC INTERACTIONS
GALACTIC EVOLUTION
GALAXIES
GALAXY CLUSTERS
GRAVITATIONAL INTERACTIONS
IMPULSE APPROXIMATION
INTERACTIONS
MANY-BODY PROBLEM