Revealing the nature of long-period transients with space-based gravitational-wave interferometers

TL;DR

This paper explores how space-based gravitational-wave detectors can identify and analyze long-period transient sources, such as binary systems with white-dwarf primaries, especially when electromagnetic observations are inconclusive.

Contribution

It quantifies the detectability of known long-period transients with space-based interferometers and discusses implications of potential detections or non-detections.

Findings

Some long-period transients could be detectable with space-based GW detectors.

Detection likelihood depends on the chirp mass of the systems.

Non-detections can constrain the properties of these transients.

Abstract

A few members of the recently discovered class of long-period transients have been identified as binaries with white-dwarf primaries. In most cases, however, electromagnetic data are inconclusive, and isolated magnetars or compact binaries remain viable. If the pulsation period matches that of the orbit -- as is the case for ILT J1101+5521 and GLEAM-X J0704--37 -- some of these elusive radio transients could be gravitational-wave bright in the mHz band. Space-based interferometers could thus be used to provide independent constraints on their nature. We quantify the signal-to-noise ratio for the known systems under various scenarios and show that a few could be detectable for sufficiently large chirp masses. Astrophysical implications for (non)detections are discussed.