LISA stellar-mass black hole searches with semicoherent and particle-swarm methods

TL;DR

This paper introduces a novel semi-coherent and particle swarm-based method for detecting long-duration, broadband gravitational wave signals from stellar-mass black hole binaries in LISA data, demonstrating its effectiveness through simulations.

Contribution

It combines semi-coherent likelihood analysis with particle swarm optimization to efficiently explore large parameter spaces for gravitational wave signals.

Findings

Successfully applied to simulated zero-noise LISA data for stellar-mass black hole binaries.

Demonstrated the method's ability to localize signals in parameter space.

Showcased potential for extension to EMRI searches in LISA data.

Abstract

This paper considers the problem of searching for quiet, long-duration and broadband gravitational wave signals, such as stellar-mass binary black hole binaries, in mock LISA data. We propose a method that combines a semi-coherent likelihood with the use of a particle swarm optimizer capable of efficiently exploring a large parameter space. The semi-coherent analysis is used to widen the peak of the likelihood distribution over parameter space, congealing secondary peaks and thereby assisting in localizing the posterior bulk. An iterative strategy is proposed, using particle swarm methods to initially explore a wide, loosely-coherent likelihood and then progressively constraining the signal to smaller regions in parameter space by increasing the level of coherence. The properties of the semi-coherent likelihood are first demonstrated using the well-studied binary neutron star signal GW170817. As a proof of concept, the method is then successfully applied to a simplified search for a stellar-mass binary black hole in zero-noise LISA data. Finally, we conclude by discussing what remains to be done to develop this into a fully-capable search and how the method might also be adapted to tackle the EMRI search problem in LISA.