1. How to Weigh a Black Hole and Other Adventures in Quasar Physics
Vikram Singh

2. What is a black hole?

3. A black hole is an object whose gravity is so powerful that not even light can escape it.

4. No Escape
Nothing can escape from within the event horizon because nothing can go faster than light.
No escape means there is no more contact with something that falls in. It increases the hole mass, changes the spin or charge, but otherwise loses its identity.
BLACK HOLES DON’T SUCK!

5. Escape Velocity Initial kinetic Final gravitational potential energy=
(Escape velocity) G  (mass) =
(radius)

6. Fill in your favorite city map here.
The event horizon of a 3MSun black hole is also about as big as a small city.

7. “Gargantua” from interstellar
100 Million Solar Masses

8. Supermassive black hole (millions to billions of solar masses)
Theoretical Paradigm
Supermassive black hole (millions to billions of solar masses)
Powered by an accretion disk.
Jet mechanisms proposed, but very uncertain.
Also, an “obscuring torus” seems to be present. (Unified models apply here.)

9. From our sun to the galactic core
Groups at Max Planck and UCLA have been observing the center of the Milky Way for over two decades, tracing the orbits of stars. The mass of the central dark object lurking there is about 4 million solar masses.

10. What makes an AGN active?
Need a supply of gas to feed to the black hole
Supermassive Black holes from 1 million to >1 billion solar masses!
(Scales as a few percent of galaxy bulge mass)
Collisions disturb regular orbits of stars and gas clouds
Could feed more gas to the central region
Galactic orbits were less organized as galaxies were forming, also recall the “hierarchical” galaxy formation
Expect more gas to flow to central region when galaxies are young => Quasars (“quasar epoch” around z=2 to z=3)
All galaxies have massive black holes in them
They are just less active now because gas supply is less

11. Accretion Disks
Black hole is “active” only if gas is present to spiral into it
Isolated stars just orbit black hole same as they would any other mass
Gas collides, tries to slow due to friction, and so spirals in (and heats up)
Conservation of angular momentum causes gas to form a disk as it spirals in

12. Black Holes powering active Galaxies: Seyferts and quasars

13. Black Holes powering active Galaxies: Seyferts and quasars

14. Red = radio Blue = visible
3C31
Red = radio Blue = visible

15. Many Views of Active Galaxy Centaurus A

16. Taking a step back to fundamentals: Arguments for Black Holes in AGNs
Energy Considerations
Nuclear luminosities in excess of 1013 suns
Gravitational release capable of converting on order 10% rest mass to energy
Rapid Variability
Timescales < 1 day imply very small source
Radio Jet Stability implies large, stable mass with large angular momentum

17. How Can We Measure Masses in space
How Can We Measure Masses in space? Remember Newton’s Version of Kepler’s Third Law

18. Virial Mass Estimates M = f (r ΔV2 / G) r = scale length of region
ΔV is the velocity dispersion
f is a factor of order unity dependent upon geometry and kinematics
Estimates therefore require size scales and velocities, and verification to avoid pitfalls (eg: radiative acceleration).

19. Measuring Black Hole Masses in “Nearby” Galaxies
Sagittarius A* in the Milky Way
Water Masers in NGC 4258, a few others
Spatially Resolved Gas or Stellar Dynamics Using the Hubble Space Telescope (HST)

20. The “M-sigma” Relation
Black Hole Masses are about 0.1% of the central galactic bulge mass (a big surprise to theorists) and tightest correlation is with the stellar velocity dispersion (after Gebhardt et al. 2000).

21. Black Hole Mass from Quasar Spectra
e.g., Vestergaard et al. (2006, 2009) Hα
Another important parameter in AGN is the black hole mass, which isn’t necessarily a typical SED project but I can really get at this with my quasi-simultaneous spectra.
How do you measure M in AGN?
Spectrum, CIV at high redshift and Hβ at low.
Ideally measurements using these lines in the same object would agree, but there’s scatter of a factor of a few between them.
I’m interested in understanding this scatter so that I can reduce it. Hβ
log(Fλ)
C IV
Mg II
Rest λ (Angstroms)

22. HYDROGEN BETA and OXYGEN [III]

23. FORBIDDEN LINES

24. SDSS: Sloan Digital SKY SURVEY The LARGEST SKY SURVEY IN HUMAN HISTORY

25. VLA: THE VERY LARGE ARRAY, NM

26. RADIO MAPS OF QUASARS

27. MBH from Hβ: Orientation Issues
Wills and Browne (1986)
Face On
Edge On

28. MBH from Hβ: Orientation Issues
Runnoe et al. (2013a)
Face On
Face On
Edge On
Edge On

29. Brotherton, M.S., Singh, V., Runnoe, J.C., 2015
MBH from Hβ: Orientation Issues
Brotherton, M.S., Singh, V., Runnoe, J.C., 2015
How to look for Hβ-based black hole mass orientation bias when C IV is not available?
Use stellar velocity dispersion, here estimated for about 400 radio-loud quasars with z < 0.75 from [O III] FWHM in SDSS spectra. Log R from FIRST.
Sample shows strong correlation, but a little weird compared to Wills & Browne (1986).
Edge On
Face On

30. NEW PHYSICS
Discovery of a new subset of supermassive black holes with accretion disks moving at 10% the speed of light!
We’re moving closer to a Unified model for AGN and Galaxies, in general. Perhaps a Main Sequence for galaxies?
Further understanding of the formation and evolution of galaxies and the role of dark matter in providing structure to the universe.
Problem with gravity on large scales???
Lots of stuff to work on still!

31. ACKNOWLEDGEMENTS
Prof. Michael S. Brotherton for being my best friend and mentor. It took us two years and quite a few beers to finish this project.
Dr. Jessie Runnoe (Mike’s former grad student) for always being there when I needed help and for being a good friend.
Wyoming EPSCoR for their grant (summer 2014) that helped me put the hours I needed to get this done and not go broke!
SPS and the Physics Dept. for funding to presenting my research at the 225th AAS Conference in Seattle, WA.
And … To the great minds that have laid the foundation for us to conquer the universe. We are all star children, indeed!