Gravitational wave signatures and detectability of the mass transfer effect in compact binaries

TL;DR

This paper investigates how mass transfer in compact binary systems affects gravitational wave signals, deriving analytical models and demonstrating that space-based detectors can measure mass transfer rates and individual white dwarf masses with high precision.

Contribution

It provides analytical expressions for gravitational wave frequency evolution considering mass transfer and shows that mass transfer effects can be accurately measured by space-based detectors.

Findings

Mass transfer rate can be measured with an accuracy of 10^{-7} M_sun/year.

Including mass transfer effects improves the measurement of white dwarf masses.

Gravitational wave signals can reveal detailed properties of binary systems.

Abstract

The mass transfer process is prevalent during the inspiral phase of compact binary systems. Our study focuses on systems comprising low-mass white dwarfs, particularly in neutron star-white dwarf binaries and double white dwarf binaries, where a stable mass transfer process occurs at low frequencies. By analyzing the evolution of gravitational wave frequencies in the presence of mass transfer within quasi-circular orbits, we derive an analytical expression for the time-dependent frequency across different frequency bands and the waveforms emitted by compact binaries. Considering gravitational waves emitted by compact binaries in the $1\thicksim10$ mHz band, based on the Fisher analysis, we find that the mass transfer rate can be measured as accurately as $10^{-7} M_\odot/\text{year}$ by space-based gravitational-wave detectors with a signal-to-noise ratio of the order of $10^3$. Including the mass transfer effect in the waveforms provides a new possibility to measure the individual masses of double white dwarf binaries. The relative error of measured white dwarf masses can be down to the order of $0.01$.