English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

During the evolution of density inhomogeneties in an $\Omega=1$, matterdominated universe, the typical density contrast changes from $\delta\simeq10^{-4}$ to $\delta\simeq 10^2$. However, during the same time, the typicalvalue of the gravitational potential generated by the perturbations changesonly by a factor of order unity. This significant fact can be exploited toprovide a new, powerful, approximation scheme for studying the formation ofnonlinear structures in the universe. This scheme, discussed in this paper,evolves the initial perturbation using a Newtonian gravitational potentialfrozen in time. We carry out this procedure for different intial spectra andcompare the results with the Zeldovich approximation and the frozen flowapproximation (proposed by Mattarrese et al. recently). Our results are in farbetter agreement with the N-body simulations than the Zeldovich approximation.It also provides a dynamical explanation for the fact that pancakes remain thinduring the evolution. While there is some superficial similarity between thefrozen flow results and ours, they differ considerably in the velocityinformation. Actual shell crossing does occur in our approximation; also thereis motion of particles along the pancakes leading to further clumping. Thesefeatures are quite different from those in frozen flow model. We also discussthe evolution of the two-point correlation function in various approximations.Comment: 10 pages, TeX, 6 figures available on request, IUCAA -14/93(  Corrections for mailing error

Non-linear evolution of density perturbations using the approximate constancy of the gravitational potential