The Mildly Non-Linear Regime of Structure Formation

?�?�N�?� ?? ??N�?�??N? ??N??�?�?????�N�???? : 2011-09-22T20:00:01Z

????N�??N�N� ??N??�?�?????�N�???? ?? ????N?N�??N�N?N�N� :
Svetlin Tassev
Matias Zaldarriaga

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?s?????�??N�?�N�???? ?? cN�?�N�N??�: 25 pages, 13 figures; accepted in JCAP; fixed irrelevant factor in equation; added a note on our analytical result
?Y?�N�????N�???�N? ???�N�?�????N�??N?: astro-ph.CO

?�N??� ???�N�?�????N�???? : astro-ph.CO

?sN�?�N�?????? ???�?�??N� N?N�?�N�N???: We present a simple physically motivated picture for the mildly non-linear regime of structure formation, which captures the effects of the bulk flows. We apply this picture to develop a method to significantly reduce the sample variance in cosmological N-body simulations at the scales relevant to the Baryon Acoustic Oscillations (BAO). The results presented in this paper will allow for a speed-up of an order of magnitude (or more) in the scanning of the cosmological parameter space using N-body simulations for studies which require a good handle of the mildly non-linear regime, such as those targeting the BAO. Using this physical picture we develop a simple formula, which allows for the rapid calculation of the mildly non-linear matter power spectrum to percent level accuracy, and for robust estimation of the BAO scale.

Category: Physics