Reading¶
The following pages from Dynamics and Evolution of Galactic Nuclei by David Merritt:
Chapter 4, pgs 117-120 and 176-183
Chapter 6, pgs 289–297
Reading questions¶
Q1-4 are related to the first reading, Q5-7 to the second.
(a) Why does Equation 4.2 imply that relativity is not important, and for what three reasons does relativity indeed play a part? (b) Why does capture occur specifically on orbits of high eccentricity? (You may need to do some research into this, but try to think mechanically based off of what else we’ve covered thus far.)
What is the Kerr metric, and what are the constants of motion in Kerr geometry?
What is the difference between the event horizon and the static limit?
Physically, why are there discrepancies in the capture radius and constants of motion between prograde and retrograde orbits for a maximally rotating black hole?
(a) What is capture vs. disruption? What factor(s) determine if a star passing a SMBH is captured or tidally disrupted? (b) Consider Eqns 6.2 and 6.3. Briefly explain why a Sun-like star can only be tidally disrupted by a SMBH with . What if it encounters a more massive SMBH?
(a) What is the “loss cone”? What happens to stars within it? (b) How does the loss cone relate to the feeding rate of the SMBH?
Why is diffusion in angular momentum more important than diffusion in energy for SMBH feeding?