February Monthly Meeting: “All Good Things Must Come to an END (Eccentric Nuclear Disk)”
Location: Zoom + In-Person at First Evangelical Lutheran Church (803 3rd Ave, Longmont, CO 80501)
Summary
From humans to supermassive black holes, many objects in the universe get a boost or a “kick” from certain phenomena. In the case of humans like me, the boost usually comes from caffeine or the pressure of a deadline. Supermassive black holes, on the other hand, can get a kick by emitting gravitational waves anisotropically - which means not the same way in every direction - during the merger of two black holes. Supermassive black holes lurk at the center of most galaxies and are usually surrounded by a dense region of stars called a nuclear stellar cluster. When these black holes receive a kick, the surrounding star cluster rearranges itself into a lopsided, eccentric disk. These eccentric disks are fairly abundant in the universe: our neighboring galaxy, Andromeda, hosts an eccentric disk in its nucleus for instance. In this talk, Tatsuya Akiba will present results from a series of N-body simulations which show the formation and evolution of eccentric disks after a kick gets imparted on the central supermassive black hole. Akiba will show that eccentric disks are able to produce tidal disruption events - which are when stars get ripped apart due to the supermassive black hole’s tidal gravity - with extreme efficiency. These tidal disruption events (and more!) can be used as observational signatures to follow-up future gravitational wave events and to look for these kicked supermassive black holes!
Bio
Tatsuya Akiba is an astrophysics Ph.D. candidate at the University of Colorado Boulder (expected to graduate in May, 2025). He currently works with Professor Ann-Marie Madigan on gravitational dynamics of various scales: from planetary systems around white dwarfs to star clusters around supermassive black holes. He graduated from Truman State University with B.S. degrees in physics and mathematics before joining CU Boulder. Since then, he has won several research awards/fellowships including the Raynor L. Duncombe Student Research Prize (from the Division on Dynamical Astronomy) and the Dissertation Completion Fellowship (from the CU Boulder graduate school). He is also passionate about teaching and public outreach: He has served as a Lead Graduate Student Fellow for the Center for Teaching and Learning in the past and he is currently the instructor for an introductory Python course in the CU Boulder astrophysics department.