Transfer of power in non-linear gravitational clustering

Bagla, J. S. ; Padmanabhan, T. (1997) Transfer of power in non-linear gravitational clustering Monthly Notices of the Royal Astronomical Society, 286 (4). pp. 1023-1031. ISSN 0035-8711

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We investigate the transfer of power between different scales and the coupling of modes during the non-linear evolution of gravitational clustering in an expanding universe. We start with a power spectrum of density fluctuations that is exponentially damped outside a narrow range of scales, and use numerical simulations to study the evolution of this power spectrum. Non-linear effects generate power at other scales, with most power flowing from larger to smaller scales. The 'cascade' of power leads to equipartition of energy at smaller scales, implying a power spectrum with index n≈-1. We find that such a spectrum is produced in the range 1<δ<200 for density contrast delta. This result continues to hold even when small-scale power is added to the initial power spectrum. Semi-analytic models for gravitational clustering suggest a tendency for the effective index to move towards a critical index nc≈-1 in this range. For n<nc, power in this range grows faster than linear rate, while if n>nc, it grows at a slower rate - thereby changing the index closer to nc. At scales larger than the narrow range of scales with initial power, a k4 tail is produced. We demonstrate that non-linear small scales do not affect the growth of perturbations at larger scales.

Item Type:Article
Source:Copyright of this article belongs to John Wiley and Sons.
Keywords:Cosmology: Theory; Dark Matter; Large-scale Structure of Universe
ID Code:72498
Deposited On:29 Nov 2011 05:36
Last Modified:29 Nov 2011 05:36

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