Scale-dependent halo bias in the excursion set approach

by Aseem Paranjape (ETHZ)

Wednesday 31 Oct 2012, 11:30 → 12:30 Europe/Zurich

4/2-011 - TH common room (CERN)

Understanding the clustering of dark matter halos (halo bias) is crucial to successfully using large scale structure as a cosmological tool. First I will describe how a scale-dependence of Lagrangian halo bias in Fourier-space can be captured by an appropriate *real*-space measurement. I will discuss recent results showing that the excursion set approach, which works with random walks in the smoothed real-space initial density field, naturally predicts the form of the Fourier-space bias coefficients. When combined with the idea that, in order to be physically meaningful, one must only count walks centered at peaks in the density field, this leads to predictions for the large scale (scale-independent) linear bias that are in good agreement with results from N-body simulations. I will also show preliminary measurements indicating that the scale-dependence at smaller scales is also captured well by this excursion set peaks model.