1. Lecture 10: Black Holes and How They Shine
Astronomy 5: The Formation and Evolution of the Universe
Sandra M. Faber
Spring Quarter 2007
UC Santa Cruz

2. Photon paths around objects of same mass and increasing density.

3. Baltimore seen through a strong gravitational lens

4. Approaching a black hole. R goes from 112RS down to 10 RS

5. Orbiting around a hole at 10 RS

6. We can use curved 2-d surfaces to model curved 3-d space
The surfaces stand for the flat equatorial plane around a condensed object like a dense star or a black hole. Walking uphill (outwards) is analogous to moving radially outward from the dense object. Note that you walk a long way on the surface but the radius does not change very much. The usual formula of the circumference = 2R is wrong … the circumference is smaller than you expect. This is what we mean by “curved space.”
Spacetime near a black hole
Spacetime near a dense star

7. Wormholes are mathematical solutions to GR that may not actually exist
Wormhole connecting two universes
Wormhole connecting two spots in the same universe.

8. The centers of spheroids host massive black holes
3 billion M central black hole
Relativistic “jet” of ionized plasma
When gas falls onto BHs, they become active galactic nuclei (AGN) and quasars (QSOs)
The famous active elliptical M87

9. Fly-in to the center of the M87 black hole

10. Artist’s conception of accretion disk with jet

11. Feedback generated by stellar mergers (QSO mode)
Sources of “feedback” during a merger:
• Gas is funneled into the central regions, fueling a starburst and creating a wind (Mihos & Hernquist 1994).
• Orbital kinetic energy is converted to heat in cloud-cloud collisions, which drives a wind (Cox et al. 2005).
QSO phase
• Gas driven to the center fuels a black hole, creating a quasar (QSO) whose feedback quenches further infall and star formation (Hopkins et al. 2005).

12. Birth and death of a quasar during collision of two disk galaxies (gas only, stars not shown)