Series: Astronomy Colloquium
Date: Monday 03-Apr-2017
Time: 15:00-16:00 (3:00-4:00 pm)
Location: CSS 2400
Speaker: Dr. Nicholas Stone (Columbia University)
Title: Dynamics in Dense Stellar Systems: Tidal Disruption Flares & Other Transients
In galactic nuclei, the coexistence of a dense cusp of stars with a central supermassive black hole (SMBH) leads to a unique and dramatic phenomenon: tidal disruption events (TDEs). During a TDE, the star is ripped apart by the tidal field of a massive black hole, and the eventual accretion of the stellar debris powers a luminous flare brighter than most supernovae and visible across the entire electromagnetic spectrum. Dozens of TDE flares have been discovered at optical, UV, and X-ray wavelengths in the last decade, and upcoming time domain surveys (such as ZTF, LSST, and eROSITA) will discover thousands more. Properly interpreted, a large sample of these flares holds great promise for testing questions in accretion physics and measuring the demography of quiescent supermassive black holes. I will discuss the dynamical processes that set tidal disruption event rates and the leading order role general relativity plays in the light curves of TDE flares, as well as ways in which black hole spin may be imprinted into TDE observables. TDEs are, however, only one example of the high energy transients produced by collisional stellar dynamical processes in dense star clusters (both galactic nuclei and globular clusters). Tidal capture, binary-single scatterings, and dynamical triple formation are all examples of dynamical phenomena that only arise in dense star systems, and I will discuss how these processes lead to unique sources of electromagnetic and gravitational wave radiation.
Colloquia are usually preceded by espresso and ice cream at 1:45 pm outside room PSC 1150 and are followed by an informal reception at 5:15 pm in that room. Anyone interested in talking with the speaker, or being added to the colloquium announcement email list, should contact the colloquium organizer. Lunch will normally be reserved for the speaker to talk to graduate students.
Prof. Stuart Vogel
Special accommodations for individuals with disabilities can be made by calling (301) 405-3001. It would be appreciated if we are notified at least one week in advance.