Angular Momentum, Hierarchical Clustering, and Local Density Maxima
Abstract
The growth of angular momentum in a hierarchical clustering cosmogony is studied to first order in linear theory. Structure is assumed to evolve from a primordial Gaussian density perturbation (δ) field. Realizations of such a δ-field are constructed, and local density peaks, which are assumed to be the progenitors of bound objects in such a cosmogony, are identified. The tidal field at each local peak and the tensor of inertia of the mass distribution around the peak are then calculated. The linear theory predicts that the angular momentum of bound aspherical objects, whose tensor of inertia is not aligned with the local deformation tensor, grows linearly with time (for a flat universe). The time each local peak spends in the linear regime is calculated and combined with the known inertia and deformation tensors; the angular momentum and the dimensionless spin parameter, λ, of each peak are calculated, We find an (anti)correlation (in the mean) of λ with the amplitude of δ, a trend which was predicted earlier (Hoffman). However, the scatter around this trend is considerable, which argues against the idea that the value of λ is the main factor which determines the morphological type of galaxies.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 1988
- DOI:
- 10.1086/166353
- Bibcode:
- 1988ApJ...329....8H
- Keywords:
-
- Angular Momentum;
- Cosmology;
- Galactic Clusters;
- Galactic Evolution;
- Normal Density Functions;
- Perturbation Theory;
- Computational Astrophysics;
- Space Density;
- Astrophysics;
- COSMOLOGY;
- GALAXIES: FORMATION;
- GALAXIES: INTERNAL MOTIONS