Large non-Gaussian Halo Bias from Single Field Inflation

Abstract

We calculate Large Scale Structure observables for non-Gaussianity arising from non-Bunch-Davies initial states in single field inflation. These scenarios can have substantial primordial non-Gaussianity from squeezed (but observable) momentum configurations. They generate a term in the halo bias that may be more strongly scale-dependent than the contribution from the local ansatz. We also discuss theoretical considerations required to generate an observable signature.

Figures (8)

• Figure 1: Contributions from the real (left) and imaginary (right) part of the $f_1$ to the term shown in (\ref{['f1term']}). Both are constants in lines $\tilde{x}_1={\rm constant}$, and attain the maximum value in nearly collinear configurations with $\tilde{x}_1=2.33 \, \tilde{x}_*$, and exact collinear configurations $\tilde{x}_1=0$, respectively.
• Figure 2: Contribution from the real part of $f_2$ to the term shown in (\ref{['f2term']}). This term is constant in lines $\tilde{x}_2={\rm constant}$, and attains its maximum value when $\tilde{x}_2=x_{\rm min}$.
• Figure 3: $B_{\rm GIS}$ (left) with $f_i=1+i$ and $x_*=10^{-2}$, and the local ansatz $B_{\rm local}$ (right). Both bispectra are normalized by ${\cal{B}}_{\rm GIS}={\cal{B}}_{\rm local}=6/5$ (that corresponds to $f_{NL}=1$), and have been multiplied by the factor $x_2^2 x_3^2$. $B_{\rm local}$ is large in squeezed configurations. $B_{\rm GIS}$ is largest in all collinear configurations, with a very significant over-all enhancement in squeezed triangles.
• Figure 4: $B_{\rm GIS}/B_{\rm local}$ with $f_i$ real. This figure shows the importance of collinear configurations, with an additional enhancement in the squeezed limit, to $B_{\rm GIS}$ compared to $B_{\rm local}$.
• Figure 5: The left panel shows the full integrand contributing to $\mathcal{F}^{(3)}$ for the Generalized Initial State shape, with $\mathcal{B}_{\rm GIS}=\frac{6}{5}$, $f_{i}=1+i$. The right panel shows the contribution from the isosceles squeezed limit of the shape only. The significant contributions from the nearly collinear squeezed configurations can be seen from the enhancements near the corners $\mu\approx\pm1$.