ITC Seminar - Ben Bar-Or (IAS)


Tuesday, February 7, 2017, 12:00pm to 1:00pm




Feeding central black holes with stars
Galactic nuclei and the Massive black holes in their centers are rich
environments, where the complex stellar dynamics plays an important role in
many physical phenomena. We show how the dynamics of this nearly-Keplerian
N-body system, where the angular momentum evolution is accelerated by resonant
relaxation, can be described and studied in a formal statistical mechanics
framework. We combine the Fokker-Plank description of two-body relaxation and
resonant relaxation to study the loss-cone dynamics in Galactic nuclei. We show
that low-mass black hole seeds that grow in a locally dense environment by
accreting stars in galactic nuclei that follow a universal M-sigma relation,
all grow over the age of the universe above a present-day mass scale M ~
10^5-10^6 Msun. This can explain why no Intermediate-mass black holes were
found to date, and implies that most present-day galaxies with sigma < 50 lack
a central black hole. AGNs in low mass galaxies may provide evidence for
central black holes which grow mainly by accrediting stars, and their velocity
dispersion distribution can be used to test this model.


See also: Seminars, 2016-17