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

Abstract

We investigate the effect of primordial non-Gaussianity of the local f_NL\ntype on the auto- and cross-power spectrum of dark matter haloes using\nsimulations of the LCDM cosmology. We perform a series of large N-body\nsimulations of both positive and negative f_NL, spanning the range between 10\nand 100. Theoretical models predict a scale-dependent bias correction \\Delta\nb(k,f_NL) that depends on the linear halo bias b(M). We measure the power\nspectra for a range of halo mass and redshifts covering the relevant range of\nexisting galaxy and quasar populations. We show that auto and cross-correlation\nanalyses of bias are consistent with each other. We find that for low\nwavenumbers with k&lt;0.03 h/Mpc the theory and the simulations agree well with\neach other for biased haloes with b(M)&gt;1.5. We show that a scale-independent\nbias correction improves the comparison between theory and simulations on\nsmaller scales, where the scale-dependent effect rapidly becomes negligible.\nThe current limits on f_NL from Slosar et al. (2008) come mostly from very\nlarge scales k&lt;0.01 h/Mpc and, therefore, remain valid. For the halo samples\nwith b(M)&lt;1.5-2 we find that the scale- dependent bias from non-Gaussianity\nactually exceeds the theoretical predictions. Our results are consistent with\nthe bias correction scaling linearly with f_NL.\n