Caltech — TAPIR Seminar Series

Quasi-periodic eruptions are repeating X-ray transients from supermassive black holes in nearby low-mass galactic nuclei. Their regularity, timescales and energetics suggest stellar companions orbiting at about 100 gravitational radii. They may provide unusually close dynamical probes of black holes and electromagnetic counterparts to extreme mass-ratio inspirals, a target for future space-based gravitational-wave observatories such as LISA. Joheen Chakraborty reviews the thirteen known systems, including the unexpected appearance of several in accretion discs created by tidal disruption events. The talk covers observations and theoretical developments, spectroscopic constraints on emission, the use of eruption timing to investigate orbital dynamics, and what event-rate estimates imply for inspiral formation. Hybrid seminar: attend in 370 Cahill, Caltech, Pasadena, California, United States, or remotely through the public Zoom meeting.