Milli-Hertz Gravitational-wave Background Produced by Quasiperiodic Eruptions

Abstract Extreme-mass-ratio inspirals (EMRIs) are important targets for future space-borne gravitational-wave (GW) detectors, such as the Laser Interferometer Space Antenna (LISA). Recent works suggest that EMRIs may reside in a population of newly discovered X-ray transients called “quasiperiodic eruptions” (QPEs). Here, we follow this scenario and investigate whether LISA could detect QPEs. We consider two specific models, which QPEs made either stellar-mass objects moving on circular orbits around massive black holes (MBHs) or white dwarfs (WDs) eccentric MBHs. find case five detected so far too weak to be resolvable by LISA. However, if WD–MBH binaries, they radiate GWs over wide range frequencies. The broad spectra overlap form background peaks milli-Hertz band has signal-to-noise ratio 9–17 even most pessimistic scenario. presence GW impact searches seed at high redshift well binary local universe.