Determining the nature of white dwarfs from low-frequency gravitational waves

TL;DR

This paper explores how low-frequency gravitational wave detectors like LISA can determine the properties of white dwarfs and predict tidal disruption events by massive black holes, enabling precise astrophysical measurements.

Contribution

It introduces a theoretical framework for using LISA-like detectors to constrain white dwarf equations of state and predict disruption times with high accuracy.

Findings

LISA can accurately determine the position and timing of white dwarf tidal disruptions.

The mass-radius relation of white dwarfs can be constrained to 0.1% accuracy.

LISA can forecast electromagnetic follow-up observations of disruption events.

Abstract

An extreme-mass-ratio system composed of a white dwarf (WD) and a massive black hole can be observed by the low-frequency gravitational wave detectors, such as the Laser Interferometer Space Antenna (LISA). When the mass of the black hole is around $10^4 \sim 10^5 M_\odot$, the WD will be disrupted by the tidal interaction at the final inspiraling stage. The event position and time of the tidal disruption of the WD can be accurately determined by the gravitational wave signals. Such position and time depend upon the mass of the black hole and especially on the density of the WD. We present the theory by using LISA-like gravitational wave detectors, the mass-radius relation and then the equations of state of WDs could be strictly constrained (accuracy up to $0.1\%$). We also point out that LISA can accurately predict the disruption time of a WD, and forecast the electromagnetic follow-up of this tidal disruption event.