How dark matter halos cluster in Lagrangian space

We investigate the clustering of dark matter halos in Lagrangian space in t erms of their two-point correlation function. Analyzing a set of collisionl ess scale-free 128(3) particle N-body simulations with spectral indices Il = -2, -1, we measure the first two Lagrangian bias parameters b(1) and b(2) relating halo and mass correlations. We find that the Mo & White leading-o rder formula for b(1), describes the clustering of halos with mass M greate r than or similar to M-* (where M-* indicates the characteristic nonlinear mass) quite accurately. Smaller halos turn out to be less clustered in Lagr angian space than predicted by Mo & White. Our findings are consistent with the recent results of Jing for the clustering of halo populations in Euler ian space, demonstrating that the discrepancies between the N-body and anal ytical Mo Br White prediction for the bias exist already in Lagrangian spac e. This shows that a more refined theoretical algorithm for selecting halos in the initial conditions needs to be developed. Finally, we present a ver y accurate fitting formula for the linear halo bias factor b(1) in Lagrangi an space.