Non-Gaussianities due to Relativistic Corrections to the Observed Galaxy Bispectrum

Understand

High-precision constraints on primordial non-Gaussianity (PNG) will significantly improve our understanding of the physics of the early universe.

• Among all the subtleties in using large scale structure observables to constrain PNG, accounting for relativistic corrections to the clustering statistics is particularly important for the upcoming galaxy surveys covering progressively larger fraction of the sky.
• We focus on relativistic projection effects due to the fact that we observe the galaxies through the light that reaches the telescope on perturbed geodesics.
• These projection effects can give rise to an effective $f_{\rm NL}$ that can be misinterpreted as the primordial non-Gaussianity signal and hence is a systematic to be carefully computed and accounted for in modelling of the bispectrum.