TAPIR Seminar

In person: 370 Cahill. To Join via Zoom: 851 0756 7442

ABSTRACT: Quasi-periodic eruptions (QPEs) are a newly discovered class of repeating X-ray transients originating from supermassive black holes (SMBHs) in nearby, low-mass galaxy nuclei. Their regularity, timescales, and energetics suggest they are driven by stellar companions orbiting the SMBH at ~100 Rg, providing the closest-yet dynamical probe and the first observed counterparts to extreme mass-ratio inspirals (EMRIs), long anticipated gravitational wave sources for upcoming space-based detectors (e.g. LISA).  Thirteen QPEs are known, and in an unexpected twist, several have emerged from the accretion disks formed in tidal disruption events. I will give an overview of the surprising discoveries, observational properties, and theoretical progress in QPEs, including spectroscopic constraints on their emission mechanisms, prospects for probing orbital dynamics in the SMBH vicinity with QPE timings, and estimates of the QPE rate and its implications for EMRI formation.