Astronomy and Astrophysics – Astrophysics – Cosmology and Extragalactic Astrophysics
Scientific paper
2010-09-03
Astron. Astrophys. (2011), 527, A87
Astronomy and Astrophysics
Astrophysics
Cosmology and Extragalactic Astrophysics
29 pages
Scientific paper
We investigate the building of unified models that can predict the matter-density power spectrum and the two-point correlation function from very large to small scales, being consistent with perturbation theory at low $k$ and with halo models at high $k$. We use a Lagrangian framework to re-interpret the halo model and to decompose the power spectrum into "2-halo" and "1-halo" contributions, related to "perturbative" and "non-perturbative" terms. We describe a simple implementation of this model and present a detailed comparison with numerical simulations, from $k \sim 0.02$ up to $100 h$Mpc$^{-1}$, and from $x \sim 0.02$ up to $150 h^{-1}$Mpc. We show that the 1-halo contribution contains a counterterm that ensures a $k^2$ tail at low $k$ and is important not to spoil the predictions on the scales probed by baryon acoustic oscillations, $k \sim 0.02$ to $0.3 h$Mpc$^{-1}$. On the other hand, we show that standard perturbation theory is inadequate for the 2-halo contribution, because higher order terms grow too fast at high $k$, so that resummation schemes must be used. We describe a simple implementation, based on a 1-loop "direct steepest-descent" resummation for the 2-halo contribution that allows fast numerical computations, and we check that we obtain a good match to simulations at low and high $k$. Our simple implementation already fares better than standard 1-loop perturbation theory on large scales and simple fits to the power spectrum at high $k$, with a typical accuracy of 1% on large scales and 10% on small scales. We obtain similar results for the two-point correlation function. However, there remains room for improvement on the transition scale between the 2-halo and 1-halo contributions, which may be the most difficult regime to describe.
Nishimichi Takahiro
Valageas Patrick
No associations
LandOfFree
Combining perturbation theories with halo models 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 Combining perturbation theories with halo models, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Combining perturbation theories with halo models will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-684455