SRON astronomer Valeriya Korol receives an NWO Vidi grant to predict the gravitational-wave signal that future space detector LISA will measure from double white dwarfs in the Milky Way. The project aims to map these stellar fossils and better understand how the Milky Way assembled over time. It combines observations from ESA’s Gaia telescope with gravitational-wave predictions for LISA.
When stars like our Sun reach the end of their fuel supply, they push out their outer layers and leave behind a white dwarf. Without nuclear fusion in the core to counterbalance gravity, its material becomes extremely dense. A ping-pong ball made of white dwarf material has the same mass as a fully loaded truck. Because white dwarfs form the stellar graveyard of small and medium-sized stars, they preserve clues to the Milky Way’s star formation history. The catch is that white dwarfs are small and emit little light, making them difficult to observe beyond our immediate Galactic neighbourhood.
A new way to study these elusive objects farther away is through gravitational waves, which they emit when orbiting close to each other in a binary system. Korol’s research brings together two major European space missions: ESA’s Gaia, which maps the positions and motions of over a billion stars, and the upcoming Laser Interferometer Space Antenna (LISA), which will detect gravitational waves from compact binary systems across the Milky Way. LISA, to be launched around 2037, is partly developed by SRON.
In preparation for the LISA mission, Korol will use Gaia observations to outline the population of nearby double white dwarfs and predict their gravitational-wave signals, both as individually detectable sources and as a collective background of weaker sources. ‘By anchoring these predictions in real-life data, we can better interpret LISA’s future observations. We need to predict the signals that LISA will measure because then we know what reality lies behind that observed signal,’ says Korol.
The NWO Vidi grant allows Korol to hire two PhD students in collaboration with Leiden University.