Eccentric double white dwarfs as LISA sources in globular clusters

TL;DR

This paper demonstrates that eccentric double white dwarfs formed through dynamical interactions in globular clusters can be detected by LISA, providing a new way to identify these systems and study their formation.

Contribution

It shows that LISA can detect eccentric DWDs in globular clusters at significant distances, revealing their dynamical origins and expanding the understanding of gravitational wave sources.

Findings

Multiple harmonics from eccentric DWDs detectable by LISA at high SNR.

Eccentric DWDs can be distinguished from neutron star systems.

LISA can identify these systems in globular clusters where electromagnetic detection is challenging.

Abstract

We consider the formation of double white dwarfs (DWDs) through dynamical interactions in globular clusters. Such interactions can give rise to eccentric DWDs, in contrast to the exclusively circular population expected to form in the Galactic disk. We show that for a 5-year Laser Interferometer Space Antenna (LISA) mission and distances as far as the Large Magellanic Cloud, multiple harmonics from eccentric DWDs can be detected at a signal-to-noise ratio higher than 8 for at least a handful of eccentric DWDs, given their formation rate and typical lifetimes estimated from current cluster simulations. Consequently the association of eccentricity with stellar-mass LISA sources does not uniquely involve neutron stars, as is usually assumed. Due to the difficulty of detecting (eccentric) DWDs with present and planned electromagnetic observatories, LISA could provide unique dynamical identifications of these systems in globular clusters.