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

What is a black hole?

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

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!

Escape Velocity Initial kinetic Final gravitational potential energy = (Escape velocity)2 G  (mass) = 2 (radius)

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

“Gargantua” from interstellar 100 Million Solar Masses

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.)

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.

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

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

Black Holes powering active Galaxies: Seyferts and quasars

Black Holes powering active Galaxies: Seyferts and quasars

Red = radio Blue = visible 3C31 Red = radio Blue = visible

Many Views of Active Galaxy Centaurus A

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

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

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).

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)

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).

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)

HYDROGEN BETA and OXYGEN [III]

FORBIDDEN LINES

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

VLA: THE VERY LARGE ARRAY, NM

RADIO MAPS OF QUASARS

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

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

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

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!

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!