Series: Astronomy Colloquium
Date: Wednesday 10-Feb-2021
Time: 16:00-17:00 (4:00-5:00 pm)
Location: Zoom
Speaker: Dr. Erez Michaely (UMD)
Title: Collisional dynamics in the field:Ultra-wide BH systems as sources of GW signals
Dynamical interactions are known to play an important role in the evolution of dense stellar systems such as globular clusters and galactic nuclei. In contrast, the galactic field (where most of the stellar systems are) is a low-density environment, where strong stellar encounters were thought to be too rare to play any role in collisional dynamics. However, the low density in the field also allows for the existence of long-lived ultra-wide systems which would have been quickly destroyed in a dense environment. The large separation of such binaries can therefore compensate for the low densities and still allow for relatively high rate of interactions with field stars. Such interactions change the orbital properties of the binaries or outer binaries in case of triples. Therefore, when considering the evolution of ultra-wide systems one needs to account for random gravitational interaction with passing stars, flybys, even in low density environments like the field of the host galaxy. The outcome of the interactions between ultra-wide black-holes (BH) systems with random field stars may excite the systems eccentricity sufficiently to radiate gravitational waves (GW) and drive the system to a merger within Hubble time. This channel may explain a fraction of the current observed binary BH merger rate and provides predictions to future observational runs, e.g. eccentric mergers. The underlying dynamics of this channel is not unique to BH or GW sources, and have implications to other stellar exotica such: low-mass X-ray binaries, Type Ia SNe, main sequence - white dwarf collisions and more.
Colloquia for the Fall 2020 semester will be held on zoom. Contact Dr. Leslie Sage for details.
Colloquium Organizer:
Dr. Leslie Sage
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.
