Primordial physics from large-scale structure beyond the power spectrum

Abstract

We study constraints on primordial mode-coupling from the power spectrum, squeezed-limit bispectrum and collapsed trispectrum of matter and halos. We describe these statistics in terms of long-wavelength $2$-point functions involving the matter/halo density and position-dependent power spectrum. This allows us to derive simple, analytic expression for the information content, treating constraints from scale-dependent bias in the halo power spectrum on the same footing as those from higher order statistics. In particular, we include non-Gaussian covariance due to long-short mode-coupling from non-linear evolution, which manifests itself as long-mode cosmic variance in the position-dependent power spectrum. We find that bispectrum forecasts that ignore this cosmic variance may underestimate $\sigma (f_{\mathrm{NL}})$ by up to a factor $\sim 3$ for the matter density (at $z=1$) and commonly a factor $\sim 2$ for the halo bispectrum. Constraints from the bispectrum can be improved by combining it with the power spectrum and trispectrum. The reason is that, in the position-dependent power spectrum picture, the bispectrum and trispectrum intrinsically incorporate multitracer cosmic variance cancellation, which is optimized in a joint analysis. For halo statistics, we discuss the roles of scale-dependent bias, matter mode-coupling, and non-linear, non-Gaussian biasing ($b_{11}^{(h)}$). While scale-dependent bias in the halo power spectrum is already very constraining, higher order halo statistics are competitive in the regime where stochastic noise in the position-dependent halo power spectrum is low enough for cosmic variance cancellation to be effective, i.e.~for large halo number density and large $k_{\max }$. This motivates exploring this regime observationally.

48 pages, 20 figures. Comments welcome

Cited by in corpus (9)

• Primordial Non-Gaussianity from Biased Tracers: Likelihood Analysis of Real-Space Power Spectrum and Bispectrum
• Time-sliced perturbation theory with primordial non-Gaussianity and effects of large bulk flows on inflationary oscillating features
• The Covariance of Squeezed Bispectrum Configurations
• Light Fields during Inflation from BOSS and Future Galaxy Surveys
• The BINGO Project V: Further steps in Component Separation and Bispectrum Analysis
• Density reconstruction from biased tracers and its application to primordial non-Gaussianity
• Local Primordial Non-Gaussianities and Super-Sample Variance
• The Renormalization Group for Large-Scale Structure: Primordial non-Gaussianities
• Cosmology at high redshift -- a probe of fundamental physics