From Gaia to LISA: white dwarfs at the centre of the stellar revolution

This is an exciting time for stellar astrophysics as high-cadence time domain surveys (Gaia, PTF, ZTF, ATLAS, Kepler, TESS, and, in the near future, the Vera Rubin Observatory) are revolutionizing the landscape of stellar studies by allowing the exploration of the dynamic sky. Furthermore, spectroscopic surveys are ongoing (SDSS V, DESI, WEAVE, 4MOST  etc.), which will provide spectral classifications for millions of stars. Space missions are also opening new windows on stars and their remnants: 2021 alone saw the launch of JWST, with its unprecedented sensitivity in the infrared, and the first public release of the all-sky X-ray telescope eROSITA. And LISA and Roman are just around the corner. White dwarfs are at the center of this stellar revolution, as the new facilities have enabled tackling some unsolved mysteries concerning white dwarfs and their far-reaching implications for many fields of astrophysics, from the evolution of stars and their planetary systems, to supernovae, to multimessenger sources. In my talk, I will show how the precise astrometry from Gaia has dramatically improved our capability of studying young star clusters, and therefore probe the evolution of white dwarfs born from single progenitor stars. On the other hand, the Zwicky Transient Facility is shedding light on the evolution of white dwarfs in binary systems and finding the final products of such binaries. In fact, with  ZTF we are discovering a large number of white-dwarf merger remnants that can help us constrain the pathways of binary evolution that lead to merger, the number of mergers in the Galaxy and their contribution to the type Ia supernova rate, as well as help us understand the origin of strong magnetic fields in white dwarfs. I will present some early results of the search, including the discovery of some extremely peculiar white dwarfs.