Thing Invisble to See: Supermassive Black Holes Douglas Richstone University of Michigan

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M. Aller (UM) R. Bender (Munich) G. Bower (NOAO) A. Dressler (OCIW) S. Faber (UCSC) A. Filippenko (UCB) K. Gebhardt (Texas) R.Green (NOAO) L. Ho (OCIW) T. Lauer (NOAO) J. Kormendy (Texas) J. Magorrian (C U) J. Pinkney (Michigan) D. Richstone (Mich) C. Siopis (Mich) S. Tremaine (Princeton)

Summary Where does the “lore” come from –Quasars, observations of test-mass dynamics, interpretation. The current demographic picture –M-  relation, bh mass spectrum, density, comparison to quasars. Emerging developments – –Slouching toward a theory –The hunt for a “second parameter” –Extension to very low masses –Possibility of gravitational wave observation of BH mergers.

 Where does the lore come from?

3c175

Mysterious properties of quasistellar objects Rapid variability – minutes. –Light travel time across inner solar system. Directed energy output (collimated beams of high-energy particles. “Superluminal” motion. Enormous luminosities ~ suns. Objects the size of the solar system that outshine the galaxy. Quasars were populous in the youthful universe, but are rare now.

Black holes from a physics perspective Macroscopic “elementary particles”. Structure completely and “simply” determined by equations of general relativity – structure defined by minimal number of properties. Strongest gravitational fields in the universe Horizon/singularity

Black holes from astronomy perspective The hole is a deep potential well An object dropped into the hole reaches the speed of light at the horizon – and acquires kinetic energy of mc 2. Conversion of this infall energy to heat or light is a prodigious energy source (the mass of a dime is ergs).

Quasars and Black Holes Small size, large luminosity and apparent stability suggest that quasars are gravity powered. Ultimate gravitational engine is a bh. Some fraction of accreted energy is radiated (can greatly exceed thermonuclear energy). BH turns off when fuel is cut off. The decline of Quasars creates the “inverse dinosaur problem” – where are the relics.

Density of relics The light radiated by quasars is proportional to mc² of accreted matter. The mass of the bh is at least m of the accreted matter. The density of quasars mandates a density of bh of about 2 x 10 5 solar masses/Mpc 3. Where are they?

3 typical bulges

Circular and parabolic orbits

Weighing stars, planets or black holes… v ² =  GM/r  depends on the orbit

It’s idiocy to ignore the details - Stanley Kunitz

M84

M84 hydrogen line

Orbit Superposition (Schwarzschild’s method) Assume a mass distribution. Compute the gravitational forces. Follow all the orbits. Sum the orbits to match the observed velocities. Failure rules out the mass distribution. I wish people wouldn’t call this 3 I- it is any I!

 How well does the method work?

 The current demographic picture

Results of 15 year effort Most bulges have BH (97% so far). BH mass tracks main-body parameters (L,  ).

Bulge M/L ~ 3x10 -3 h Density - 2.5x10 5 Msun/Mpc³ for h=.65 (Yu & Tremaine) - 4.8x10 5 h² Msun/Mpc³ (Aller & Richstone) -consistent results from different datasets. -S = 2.2x10 5 Msun/Mpc – 9x10 5 (Fabian & Iwasawa) qso+X-ray background (and similar from Barger).

? BIG PROBLEM ? The X-ray background energy exceeds the available sources of energy in known supermassive black holes. (the known population of SBH seems just adequate for the quasar energy).

A note on backgrounds Any background can be expressed in terms of the cosmic microwave background energy density (about 1eV/cm 3 ). u qso ~  bh ~ u qso  -1 (1 -  -gw – ejections) u stars ~ 1

Second parameter?

“Those who forget physics are doomed to repeat it.”

A taxonomy of theories for the M~v 4 relation. The bh growth is limited by a mass budget (Burkert & Silk). The bh growth is limited by a momentum budget (Fabian) BH growth is limited by angular-momentum (AGR). BH growth limited by energy conservation (Silk & Rees, Blandford). Ciotti & Ostriker, pure core collapse ).

Only gas will produce the correct Soltan number Feedback vs. fortunate conditions Accreting matter: –Stars –Degenerate objects –Dark matter –Gas

Summary Supermassive black holes are here to stay. Quasars are OK, may need some very efficient emitters. X-ray background looks OK to me. M~v 4 makes theorists salivate and may lead to a model. No second parameter yet.

Implications BH growth spurt during quasar era (is this the epoch of bulge formation?). –What is the pedigree of BH and galaxies? Co-Evolution! --- feeding, bar disruption, core scouring, mergers --- bh growh connected to galaxy evolution. Is any of this observable?

Star formation history and quasars.

“We’re looking forward to looking backward” - Alan Dressler

LISA sky

Grav waves.