Imprint of anisotropic primordial non-Gaussianity on halo intrinsic alignments in simulations

TL;DR

This study uses cosmological simulations to show that anisotropic primordial non-Gaussianity uniquely affects halo shape alignments, enabling new constraints on early universe physics through large-scale structure observations.

Contribution

First demonstration that anisotropic PNG causes a scale-dependent modification in halo shape power spectra, distinct from effects on halo density fields.

Findings

Scale-dependent $1/k^2$ modification in halo shape spectra due to PNG.

Halo density power spectrum remains unaffected by anisotropic PNG.

Potential to constrain PNG parameters with upcoming large-scale surveys.

Abstract

Using $N$-body simulations of cosmological large-scale structure formation, for the first time, we show that the anisotropic primordial non-Gaussianity (PNG) causes a scale-dependent modification, given by $1/k^2$ at small $k$ limit, in the three-dimensional power spectra of halo shapes (intrinsic alignments), whilst the conventional power spectrum of halo number density field remains unaffected. We discuss that wide-area imaging and spectrocopic surveys observing the same region of the sky allow us to constrain the quadrupole PNG coefficient $f_{\rm NL}^{s=2}$ at a precision comparable with or better than that of the cosmic microwave background.