Detecting hierarchical stellar systems with LISA

TL;DR

This paper explores how LISA can detect hierarchical stellar systems through gravitational wave signals, revealing details about their outer orbits and contributing to understanding stellar evolution and dynamics.

Contribution

It demonstrates that LISA can identify hierarchical stellar systems and measure their outer orbital parameters, providing new insights into stellar evolution and dynamics.

Findings

LISA can detect gravitational effects of hierarchical companions up to 100-year periods.

Outer orbit periods and eccentricities can be measured for systems within the mission lifetime.

Detection will shed light on the role of Kozai-Lidov oscillations in stellar mergers.

Abstract

A significant fraction of stars are members of gravitationally bound hierarchies containing three or more components. Almost all low mass stars in binaries with periods shorter three days are part of a hierarchical system. We therefore anticipate that a large fraction of compact galactic binaries detected by the Laser Interferometer Space Antenna (LISA) will be members of hierarchical triple or quadruple system. The acceleration imparted by the hierarchical companions can be detected in the gravitational wave signal for outer periods as large as 100 years. For systems with periods that are shorter than, or comparable to, the mission lifetime, it will be possible to measure the period and eccentricity of the outer orbit. LISA observations of hierarchical stellar systems will provide insight into stellar evolution, including the role that Kozai-Lidov oscillations play in driving systems towards merger.