Magnification and evolution biases in large-scale structure surveys

TL;DR

This paper analyzes how lensing magnification and Doppler effects influence galaxy clustering measurements in future large-scale structure surveys, emphasizing the importance of accurate bias modeling for precise cosmological inference.

Contribution

It provides a detailed derivation of magnification and evolution biases, clarifies existing literature, and evaluates these biases across various upcoming survey types.

Findings

Bias sensitivities depend on the luminosity function's derivatives.

Magnification and evolution biases vary significantly among different survey types.

Accurate bias modeling is crucial for interpreting future galaxy clustering data.

Abstract

Measurements of galaxy clustering in upcoming surveys such as those planned for the Euclid and Roman satellites, and the SKA Observatory, will be sensitive to distortions from lensing magnification and Doppler effects, beyond the standard redshift-space distortions. The amplitude of these contributions depends sensitively on magnification bias and evolution bias in the galaxy number density. Magnification bias quantifies the change in the observed number of galaxies gained or lost by lensing magnification, while evolution bias quantifies the physical change in the galaxy number density relative to the conserved case. These biases are given by derivatives of the number density, and consequently are very sensitive to the form of the luminosity function. We give a careful derivation of the magnification and evolution biases, clarifying a number of results in the literature. We then examine the biases for a variety of surveys, encompassing galaxy surveys and line intensity mapping at radio and optical/near-infrared wavelengths.