LISA (Laser Interferometer Space Antenna) is a low-frequency gravitational wave observatory
(0.1 mHz - 1 Hz) that will be launched by the ESA in 2035. It aims to observe several populations
of relativistic binary stars: white dwarf binaries in our Galaxy, supermassive black holes in
coalescence, stellar-mass black holes captured by supermassive black holes in galactic nuclei,
etc. In addition, we hope to observe stochastic gravitational wave signals
from the early Universe. Due to the dominant seismic noise at these frequencies, these sources
cannot be observed by ground-based detectors. The observation of these sources will provide
unique information about the history of the early Universe, the formation of large structures, the
verification of the theory of general relativity, and perhaps the nature of dark matter.
We expect to detect thousands to tens of thousands of sources during the lifetime of the
mission, with signals overlapping in time and frequency. In addition, we expect
gaps in the data and artefacts from the instrument and the environment (e.g.,
the impact of micrometeorites or asteroid flybys). We must detect all these
sources and characterise them simultaneously: this problem is often referred to as ‘global fit’ and is the main subject
of doctoral theses.
