Astro Seminar: Nicholas Stone

Speaker: Nicholas Stone (University of Wisconsin-Madison)

Location: Auditorium A (Zoom)

Title: Multimessenger Emission in Active Galactic Nuclei: from Density Waves to Gravitational Waves

Abstract: Active galactic nuclei (AGN) have long been studied as one of the Universe's most energetic sources of electromagnetic radiation.  Recent years have seen growing interest in AGN as factories of gravitational waves (GWs) as well, in particular due to the large number of stellar mass compact objects that may be embedded in AGN disks.  My talk will be focused on three questions.  First, how do populations of embedded stellar mass black holes (BHs) form, and how do they back-react on the AGN disk itself?  Second, how do embedded BHs pair up into binaries and merge to emit LIGO/Virgo/Kagra (LVK)-band GWs?  Third, how promising are AGN for forming LISA-band extreme mass ratio inspiral GWs?  While definitive answers to these questions are lacking at present, I will review both theoretical work (by myself and others) on them as well as the observational evidence that exists at present, especially from LVK GW populations.