Halo clustering and gNL-type primordial non-gaussianity

A wide range of multifield inflationary models generate non-Gaussian initial conditions in which the initial adiabatic fluctuation is of the form (ζ_G+g_NLζ_G³). We study halo clustering in these models using two different analytic methods: the peak-background split framework, and brute force calculation in a barrier crossing model, obtaining agreement between the two. We find a simple, theoretically motivated expression for halo bias which agrees with N-body simulations and can be used to constrain g_NL from observations. We discuss practical caveats to constraining g_NL using only observable properties of a tracer population, and argue that constraints obtained from populations whose observed bias is lsim2.5 are generally not robust to uncertainties in modeling the halo occupation distribution of the population.