Galaxy number counts at second order in perturbation theory: A leading-order term comparison

Abstract

The Galaxy number density is a key quantity to compare theoretical predictions to the observational data from current and future large scale structure surveys. The precision demanded by these stage IV surveys requires the use of second order cosmological perturbation theory. Based on the independent calculation published previously, we present the result of the comparison with the results of three other groups at leading order. Overall we find that the differences between the different approaches lie mostly on the definition of certain quantities, where the ambiguity of signs results in the addition of extra terms at second order in perturbation theory.