# Predicting the LISA white dwarf binary population in the Milky Way with cosmological simulations

## TL;DR

This paper predicts the properties and distribution of white dwarf binary systems detectable by LISA, using a novel combination of cosmological simulations and binary population synthesis to inform gravitational wave source models.

## Contribution

It introduces a cosmologically realistic model of white dwarf binaries in the Milky Way by integrating high-resolution simulations with binary evolution, providing new insights into their distribution and properties.

## Key findings

- He-He and He-CO systems are the main LISA sources.
- Galactic components contribute differently to the GW signal.
- Sky map of sources differs from previous models.

## Abstract

Short-period (P<1 hour) white dwarf binaries will be the most numerous sources for the space-based gravitational wave detector LISA. Based on thousands of resolved systems, we will be able to constrain binary evolution and provide a new map of the Milky Way and its surroundings. Here we predict the main properties of populations of different types of detached white dwarf binaries detected by LISA. For the first time, we combine a high-resolution cosmological simulation of a Milky Way-mass galaxy (from the FIRE project) with a binary population synthesis model for low and intermediate mass stars. Our model therefore provides a cosmologically realistic star formation and metallicity history for the galaxy and naturally produces its different components such as the thin and thick disk, the bulge, the stellar halo, and satellite galaxies and streams. With the simulation, we show how different galactic components contribute differently to the gravitational wave signal, due to their typical age and distance distributions. We find that the dominant LISA sources will be He-He systems and He-CO systems with important contributions from the thick disk and bulge but also a few systems in the stellar halo. The resulting sky map of the sources is different from previous models, with important consequences for the searches for electromagnetic counterparts and data analysis. We also emphasize that much of the science-enabling information regarding white dwarf binaries, such as the chirp mass and the sky localisation, becomes increasingly rich with long observations, including an extended mission up to 8 years.