Premerger observation and characterization of massive black hole binaries

TL;DR

This paper presents a real-time method for early detection and characterization of massive black hole binaries with LISA, enabling prompt multimessenger follow-up and improved mission planning.

Contribution

It introduces a zero-latency whitening filter technique for premerger detection and source characterization of black hole binaries with minimal computational cost.

Findings

Reliable detection as early as 14 days premerger at SNR ≥ 8

Accurate estimation of merger time, chirp mass, and sky location

Method requires minimal computational resources

Abstract

We demonstrate an end-to-end technique for observing and characterizing massive black hole binary signals before they merge with the LISA space-based gravitational-wave observatory. Our method uses a zero-latency whitening filter, originally designed for rapidly observing compact binary mergers in ground-based observatories, to be able to observe signals with no additional latency due to filter length. We show that with minimal computational cost, we are able to reliably observe signals as early as 14 days premerger as long as the signal has accrued a signal-to-noise ratio of at least 8 in the LISA data. We also demonstrate that this method can be used to characterize the source properties, providing early estimates of the source's merger time, chirp mass, and sky localization. Early observation and characterization of massive black holes is crucial to enable the possibility of rapid multimessenger observations, and to ensure that LISA can enter a protected operating period when the merger signal arrives.