Modeling multi-stream flow in collisionless matter: approximations for large-scale structure beyond shell-crossing

Details Modeling multi-stream flow in collisionless matter: approximations for large-scale structure beyond shell-crossing Modeling multi-stream flow in collisionless matter: approximations for large-scale structure beyond shell-crossing

1997-02-17

arxiv.org/abs/astro-ph/9702139v3

Astron.Astrophys.335:395-402,1998

Astronomy and Astrophysics

Astrophysics

matching published version in A&A; LaTeX2e 8 pages, uses aa.cls

Scientific paper

The generally held view that a model of large-scale structure, formed by collisionless matter in the Universe, can be based on the matter model ``dust'' fails in the presence of multi-stream flow, i.e., velocity dispersion. We argue that models for large-scale structure should rather be constructed for a flow which describes the average motion of a multi-stream system. We present a clearcut reasoning how to approach the problem and derive an evolution equation for the mean peculiar-velocity relative to background solutions of Friedmann-Lema\^\i tre type. We consider restrictions of the nonlinear problem and show that the effect of velocity dispersion gives rise to an effective viscosity of non-dissipative gravitational origin. We discuss subcases which arise naturally from this approach: the ``sticky particle model'' and the ``adhesion approximation''. We also construct a novel approximation that features adhesive action in the multi-stream regime while conserving momentum, which was considered a drawback of the standard approximation based on Burger's equation. We finally argue that the assumptions made to obtain these models should be relaxed and we discuss how this can be achieved.

Affiliated with

Also associated with

No associations

Rating

Modeling multi-stream flow in collisionless matter: approximations for large-scale structure beyond shell-crossing does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Modeling multi-stream flow in collisionless matter: approximations for large-scale structure beyond shell-crossing, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Modeling multi-stream flow in collisionless matter: approximations for large-scale structure beyond shell-crossing will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-10561