# Observationally driven Galactic double white dwarf population for LISA

**Authors:** Valeriya Korol, Na'ama Hallakoun, Silvia Toonen, Nikolaos Karnesis  
**arXiv:** [2109.10972](https://arxiv.org/abs/2109.10972)  
**Date:** 2021-09-22  
**Summary page:** https://www.summarizepaper.com/en/paper/2109.10972v2/

## Key points

- The Laser Interferometer Space Antenna (LISA) is a future European Space Agency's gravitational-wave observatory.
- LISA will detect numerous individually detectable double white dwarfs (DWDs) as well as an unresolved confusion foreground produced by the underlying Galactic population.
- Accurate models of the Galactic DWD population are crucial for testing and quantitatively defining the science objectives of LISA.
- Modelling of the DWD population for LISA has been based on binary population synthesis (BPS) techniques so far.
- This study aims to construct an observationally driven population model using a statistical analysis of the local DWD population based on two complementary large, multi-epoch, spectroscopic samples: the Sloan Digital Sky Survey (SDSS), and the Supernova Ia Progenitor surveY (SPY).
- The authors calculate the number of LISA-detectable DWDs and the Galactic confusion foreground based on their assumptions and results.
- Their observationally driven estimates yield 2-5 times more individually detectable DWDs than various BPS forecasts and a significantly different shape of the DWD confusion foreground.
- These findings have important implications for the LISA mission.
- The comparison between several variations to their underlying assumptions shows that their observationally driven model is robust, with an uncertainty in the total number of LISA-detectable DWDs in the order of 20 per cent.
- Overall, this study provides valuable insights into constructing realistic models of Galactic DWD populations for future gravitational-wave observatories like LISA.

## Summary

The Laser Interferometer Space Antenna (LISA) is a future European Space Agency's gravitational-wave observatory that will detect numerous individually detectable double white dwarfs (DWDs) as well as an unresolved confusion foreground produced by the underlying Galactic population. Accurate models of the Galactic DWD population are crucial for testing and quantitatively defining the science objectives of LISA. However, so far, the modelling of the DWD population for LISA has been based on binary population synthesis (BPS) techniques. This study aims to construct an observationally driven population model using a statistical analysis of the local DWD population based on two complementary large, multi-epoch, spectroscopic samples: the Sloan Digital Sky Survey (SDSS), and the Supernova Ia Progenitor surveY (SPY). The authors calculate the number of LISA-detectable DWDs and the Galactic confusion foreground based on their assumptions and results. They find that their observationally driven estimates yield 2-5 times more individually detectable DWDs than various BPS forecasts and a significantly different shape of the DWD confusion foreground. These findings have important implications for the LISA mission. The comparison between several variations to their underlying assumptions shows that their observationally driven model is robust, with an uncertainty in the total number of LISA-detectable DWDs in the order of 20 per cent. Overall, this study provides valuable insights into constructing realistic models of Galactic DWD populations for future gravitational-wave observatories like LISA. By employing observational data-driven approaches rather than relying solely on theoretical models, researchers can improve our understanding of these systems' properties and better predict their detectability by gravitational-wave observatories like LISA.