Professor T. Padmanabhan

Permanent URI for this communityhttp://localhost:4000/handle/11007/2

Browse

Author: search.filters.author.Kanekar, NissimSubject: search.filters.subject.Dark matter

Search Results

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Effects of anticorrelation on gravitational clustering
    (Wiley-Blackwell, 2001-01-28) Kanekar, Nissim; Padmanabhan, T.
    We use non-linear scaling relations (NSRs) to investigate the effects arising from the existence of negative correlations on the evolution of gravitational clustering in an expanding universe. It turns out that such anti-correlated regions have important dynamical effects on ıt all scales. In particular, the mere existence of negative values for the linear two-point correlation function ξbL over some range of scales starting from l = Lo, implies that the non-linear correlation function is bounded from above at ıt all scales x < Lo. This also results in the relation ξb ∝ x-3, at these scales, at late times, independent of the original form of the correlation function. Current observations do not rule out the existence of negative ξb for 200 h-1 Mpc ła ξb ła 1000 h-1 Mpc; the present work may thus have relevance for the real Universe. The only assumption made in the analysis is the ıt existence of the NSR; the results are independent of the form of the NSR as well as of the stable clustering hypothesis.
  • No Thumbnail Available
    Item
    Non-linear density evolution from an improved spherical collapse model
    (Wiley-Blackwell, 1999-11-30) Engineer, Sunu; Kanekar, Nissim; Padmanabhan, T.
    We investigate the evolution of non-linear density perturbations by taking into account the effects of deviations from spherical symmetry of a system. Starting from the standard spherical top hat model in which these effects are ignored, we introduce a physically motivated closure condition which specifies the dependence of the additional terms on the density contrast, δ. The modified equation can be used to model the behaviour of an overdense region over a sufficiently large range of δ. The key new idea is a Taylor series expansion in (1/δ) to model the non-linear epoch. We show that the modified equations quite generically lead to the formation of stable structures in which the gravitational collapse is halted at around the virial radius. The analysis also allows us to connect up the behaviour of individual overdense regions with the non-linear scaling relations satisfied by the two point correlation function. Comment: 11 pages, 6 figures. Final version, contains added discussion and modified figures to match the accepted version.