Loop corrections in nonlinear cosmological perturbation theory 2. Two point statistics and selfsimilarity

Feb, 1996
48 pages
Published in:
  • Astrophys.J. 473 (1996) 620
e-Print:
Report number:
  • FERMILAB-PUB-96-023-A

Citations per year

1996200320102017202402468
Abstract: (arXiv)
We calculate the lowest-order non-linear contributions to the power spectrum, two-point correlation function, and smoothed variance of the density field, for Gaussian initial conditions and scale-free initial power spectra, P(k)k nP(k) \sim k~n. These results extend and in some cases correct previous work in the literature on cosmological perturbation theory. Comparing with the scaling behavior observed in N-body simulations, we find that the validity of non-linear perturbation theory depends strongly on the spectral index nn. For n<1n<-1, we find excellent agreement over scales where the variance \sigma~2(R) \la 10; however, for n1n \geq -1, perturbation theory predicts deviations from self-similar scaling (which increase with nn) not seen in numerical simulations. This anomalous scaling suggests that the principal assumption underlying cosmological perturbation theory, that large-scale fields can be described perturbatively even when fluctuations are highly non-linear on small scales, breaks down beyond leading order for spectral indices n1n \geq -1. For n<1n < -1, the power spectrum, variance, and correlation function in the scaling regime can be calculated using dimensional regularization.