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

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.

Comments: 10 pages, 2 figures, 2 tables. Minor changes to match published version