Primordial non-Gaussianities and zero bias tracers of the Large Scale Structure

Understand

We develop a new method to constraint primordial non-Gaussianities of the local kind using unclustered tracers of the Large Scale Structure.

• We show that in the limit of low noise, zero bias tracers yield large improvement over standard methods, mostly due to vanishing sampling variance.
• We propose a simple technique to construct such a tracer, using environmental information obtained from the original sample, and validate our method with N-body simulations.
• Our results indicate that $\sigma_{f_{\mathrm{NL}}^{\mathrm{loc}}}\simeq1$ can be reached using only information on a single tracer of sufficiently high number density.