Detecting Planets around Compact Binaries with Gravitational Wave Detectors in Space

TL;DR

This paper proposes a novel method to detect exoplanets around compact binary systems using gravitational wave phase modulations, potentially expanding planetary detection to distant and compact systems with space-based detectors.

Contribution

It introduces a new gravitational wave-based technique for detecting planets around compact binaries, including double white dwarfs and neutron stars, with specific detection limits and capabilities.

Findings

Planets around ~3000 Galactic double white dwarfs detectable with LISA.

Follow-on missions could detect ~1 M_J planets around double neutron stars at z~1.

Gravitational wave observations can contribute to exoplanet science.

Abstract

I propose a method to detect planets around compact binaries that are strong sources of gravitational radiation. This approach is to measure gravitational-wave phase modulations induced by the planets, and its prospect is studied with a Fisher matrix analysis. I find that, using the Laser Interferometer Space Antenna (LISA), planets can be searched for around ~3000 Galactic double white dwarfs with detection limit ~4 M_J (M_J~ 2x10^{30}g: the Jupiter mass). With its follow-on missions, planets with mass ~1 M_J might be detected around double neutron stars even at cosmological distances z~1. In this manner, gravitational wave observation has potential to make interesting contributions to extra-solar planetary science.