Scale-dependent bias induced by local non-Gaussianity: a comparison to N-body simulations

Desjacques, Vincent ; Seljak, Uroš ; Iliev, Ilian T.

In: Monthly Notices of the Royal Astronomical Society, 2009, vol. 396, no. 1, p. 85-96

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    We investigate the effect of primordial non-Gaussianity of the local fNL type on the auto- and cross-power spectra of dark matter haloes using simulations of the Λ cold dark matter cosmology. We perform a series of large N-body simulations of both positive and negative fNL, spanning the range between 10 and 100. Theoretical models predict a scale-dependent bias correction Δb(k, fNL) that depends on the linear halo bias b(M). We measure the power spectra for a range of halo mass and redshifts covering the relevant range of existing galaxy and quasar populations. We show that auto- and cross-correlation analyses of bias are consistent with each other. We find that for low wavenumbers with k < 0.03 h Mpc−1 the theory and the simulations agree well with each other for biased haloes with b(M) > 1.5. We show that a scale-independent bias correction improves the comparison between theory and simulations on smaller scales, where the scale-dependent effect rapidly becomes negligible. The current limits on fNL from Slosar et al. come mostly from very large scales k < 0.01 h Mpc−1 and, therefore, remain valid. For the halo samples with b(M) < 1.5 − 2, we find that the scale-dependent bias from non-Gaussianity actually exceeds the theoretical predictions. Our results are consistent with the bias correction scaling linearly with fNL