Magnification and evolution bias of transient sources: GWs and SNIa

TL;DR

This paper develops models for magnification and evolution biases in GW and SNIa transient sources, crucial for accurate large-scale structure measurements with upcoming third-generation surveys.

Contribution

It introduces comprehensive frameworks to compute and incorporate biases for GW and SNIa sources, enabling better relativistic correction modeling.

Findings

Biases significantly affect relativistic corrections at high redshift.

Proper bias modeling improves cross-correlation measurements.

Frameworks are applicable to future large-volume surveys.

Abstract

Third-generation gravitational wave (GW) observatories such as the Einstein Telescope and Cosmic Explorer, together with the LSST survey at the Vera Rubin Observatory, will yield an abundance of extra-galactic transient objects. This opens the exciting possibility of using GW sources and Supernovae Type Ia (SNIa) as luminosity distance tracers of large-scale structure for the first time. The large volumes accessible to these surveys imply that we may need to include relativistic corrections, such as lensing and Doppler magnification. However, the amplitude of these effects depends on the magnification and evolution biases of the transient sources, which are not yet understood. In this paper we develop comprehensive frameworks to address and model these biases for both populations of transient objects; in particular, we define how to compute these biases for GW sources. We then analyse the impact of magnification and evolution biases on the relativistic corrections and on the angular power spectrum of these sources. We show that correct modelling and implementation of these biases is crucial for measuring the cross-correlations of transient sources at higher redshifts.