Seminar by Antonio RodrÃguez, Caltech
Accreting white dwarfs (WDs) are sensitive probes of binary evolution, magnetic field generation, and accretion physics. The shortest period systems are strong sources of gravitational waves, which will be detected by LISA in the next decade. Accretion leads to X-ray emission, as well as spectacular optical variability and transient behavior. Currently, the X-ray sky is being transformed through data releases from SRG/eROSITA, which is the deepest all-sky X-ray survey in nearly thirty years. Gaia allows us to confirm that X-ray sources are in the Milky Way, and the Zwicky Transient Facility (ZTF), the deepest Northern sky time-domain optical survey, allows us to probe their variability. I will show how I have extracted meaningful science from and identified accreting WDs, neutron stars, and black holes in these datasets, which have millions to billions of objects. I will present discoveries of WDs accreting from brown dwarfs and helium-dominated planetary-mass objects, and the most extreme magnetic WD which could hold a key to our understanding of WD magnetic field generation. I will show that the latter represents a population of systems that will be easily discovered with the upcoming Rubin Legacy Survey of Space and Time (LSST). Finally, I will present two large surveys I have undertaken using these large datasets: one which provides the most definitive proof to date to show that the observed number of accreting WDs in the solar neighborhood is overestimated by population synthesis by factors of 5 to 200, and one which has yielded new systems and places constraints on the total number of accreting double white dwarfs that will be detected in gravitational waves by LISA in the next decade.
Host: Kaya Mori