Astro2020 Science White Paper: A Summary of Multimessenger Science with Galactic Binaries

TL;DR

This white paper discusses how combining gravitational wave and electromagnetic observations of Galactic binaries, especially those with short orbital periods, can significantly advance our understanding of their physics, evolution, and merger outcomes.

Contribution

It provides an overview of the scientific opportunities and recommendations for multi-messenger studies of Galactic binaries with LISA and electromagnetic telescopes.

Findings

LISA will resolve tens of thousands of Galactic binaries.

Multi-messenger observations can measure tidal effects and angular momentum transport.

Enhanced understanding of WD mergers and binary evolution.

Abstract

Galactic binaries with orbital periods less than $\approx$1 hr are strong gravitational wave sources in the mHz regime, ideal for the Laser Interferometer Space Antenna (LISA). In fact, theory predicts that \emph{LISA} will resolve tens of thousands of Galactic binaries individually with a large fraction being bright enough for electromagnetic observations. This opens up a new window where we can study a statistical sample of compact Galactic binaries in both, the electromagnetic as well the gravitational wavebands. Using multi-messenger observations we can measure tidal effects in detached double WD systems, which strongly impact the outcome of WD mergers. For accreting WDs as well as NS binaries, multi-messenger observations give us the possibility to study the angular momentum transport due to mass transfer. In this white paper we present an overview of the opportunities for research on Galactic binaries using multi-messenger observations and summarize some recommendations for the 2020 time-frame.