Violent relaxation and the R1/4 law
Open Access
- 15 December 1991
- journal article
- Published by Oxford University Press (OUP) in Monthly Notices of the Royal Astronomical Society
- Vol. 253 (4) , 703-709
- https://doi.org/10.1093/mnras/253.4.703
Abstract
Violent relaxation occurs in a finite region in space with the escape energy as no special threshold. After the escape of positive energy particles and redistribution of weakly bound particles, an isotropic equilibrium distribution function, which reproduces de Vaucouleurs' empirical R1/4 law for the surface-brightness distribution in elliptical galaxies, is predicted in a natural way. The residuals from the R1/4 law fit the surface photometry of the standard elliptical NGC 3379. In this simple picture the R1/4 law reflects neither initial conditions nor internal velocity distribution, but requires a deep central potential. As indicated by numerical simulations this can be achieved by cold dissipationless collapse which results in highly radial orbits but perhaps more naturally through dissipational processes for which there is auxiliary evidence.Keywords
This publication has 0 references indexed in Scilit: