Relativistic wide-angle galaxy bispectrum on the light-cone

TL;DR

This paper derives the full relativistic galaxy bispectrum on the light-cone, including all second-order effects, to improve the accuracy of cosmological parameter estimation from future large-scale surveys.

Contribution

It provides the first comprehensive calculation of the galaxy bispectrum incorporating all relativistic, bias, geometric, and primordial non-Gaussianity effects at second order.

Findings

First complete relativistic bispectrum including all effects.

Highlights importance of relativistic corrections at horizon scales.

Prepares for unbiased analysis of future galaxy survey data.

Abstract

Given the important role that the galaxy bispectrum has recently acquired in cosmology and the scale and precision of forthcoming galaxy clustering observations, it is timely to derive the full expression of the large-scale bispectrum going beyond approximated treatments which neglect integrated terms or higher-order bias terms or use the Limber approximation. On cosmological scales, relativistic effects that arise from observing on the past light-cone alter the observed galaxy number counts, therefore leaving their imprints on N-point correlators at all orders. In this paper we compute for the first time the bispectrum including all general relativistic, local and integrated, effects at second order, the tracers' bias at second order, geometric effects as well as the primordial non-Gaussianity contribution. This is timely considering that future surveys will probe scales comparable to the horizon where approximations widely used currently may not hold; neglecting these effects may introduce biases in estimation of cosmological parameters as well as primordial non-Gaussianity.