LISA Source Confusion

TL;DR

This paper investigates how overlapping gravitational wave signals in LISA data cause source confusion, significantly impairing parameter estimation, and finds that longer observation times and lower correlations improve source disentanglement.

Contribution

It provides a quantitative analysis of how source confusion affects parameter estimation and highlights the importance of extended mission durations for resolving overlapping signals.

Findings

Parameter resolution decays exponentially with the number of sources

Resolution deteriorates super-exponentially with signal cross-correlation

Extended observation time greatly improves source disentanglement

Abstract

The Laser Interferometer Space Antenna (LISA) will detect thousands of gravitational wave sources. Many of these sources will be overlapping in the sense that their signals will have a non-zero cross-correlation. Such overlaps lead to source confusion, which adversely affects how well we can extract information about the individual sources. Here we study how source confusion impacts parameter estimation for galactic compact binaries, with emphasis on the effects of the number of overlaping sources, the time of observation, the gravitational wave frequencies of the sources, and the degree of the signal correlations. Our main findings are that the parameter resolution decays exponentially with the number of overlapping sources, and super-exponentially with the degree of cross-correlation. We also find that an extended mission lifetime is key to disentangling the source confusion as the parameter resolution for overlapping sources improves much faster than the usual square root of the observation time.