Analytical and Numerical Models of Turnaround Densities in ΛCDM
Abstract
We will present numerical calculations of gravitating systems in a ΛCDM universe and determine the range of densities required to achieve turnaround. We use the Numerical Action Method to examine realistic models of up to 5 galaxies forming a group originating in a nearly homogeneous expanding medium. We show the effects of tidal fields and nonspherical, nonlinear interactions. We provide a fitting formula for the turnaround mass as a function of Λ based on analytical calculation of spherical infall. The fitting formula provides a ratio of the turnaround density with Λ to that given by the conventional formula for Λ=0. This work is part of an effort to study the mass distributions in nearby groups to model future SIM observations of transverse motions of galaxies.
- Publication:
-
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 2006
- Bibcode:
- 2006AAS...209.5307P