Cosmological Measurements with General Relativistic Galaxy Correlations

TL;DR

This paper assesses the impact of relativistic effects on large-scale galaxy correlation measurements and demonstrates that neglecting these effects can significantly bias cosmological parameter estimates in future surveys.

Contribution

It provides a comprehensive analysis of relativistic effects in galaxy correlations and highlights their importance for accurate cosmological parameter estimation in upcoming surveys.

Findings

Relativistic effects contribute non-negligibly to galaxy correlation signals.

Neglecting relativistic terms can bias cosmological parameters by tens of percent.

Including these effects improves the accuracy of future cosmological measurements.

Abstract

We investigate the cosmological dependence and the constraining power of large-scale galaxy correlations, including all redshift-distortions, wide-angle, lensing and gravitational potential effects on linear scales. We analyze the cosmological information present in the lensing convergence and in the gravitational potential terms describing the so-called "relativistic effects," and we find that, while smaller than the information contained in intrinsic galaxy clustering, it is not negligible. We investigate how neglecting them does bias cosmological measurements performed by future spectroscopic and photometric large-scale surveys such as SKA and Euclid. We perform a Fisher analysis using the CLASS code, modified to include scale-dependent galaxy bias and redshift-dependent magnification and evolution bias. Our results show that neglecting relativistic terms introduces an error in the forecasted precision in measuring cosmological parameters of the order of a few tens of percent, in particular when measuring the matter content of the Universe and primordial non-Gaussianity parameters. Therefore, we argue that radial correlations and integrated relativistic terms need to be taken into account when forecasting the constraining power of future large-scale number counts of galaxy surveys.