Supermassive Black Holes: The Inverse Dinosaur

Problem Douglas Richstone

University of Michigan

Summary• The ‘inverse dinosaur problem’.

– Quasars, observations of test-mass dynamics, interpretation.

• The current demographic picture– M- relation, bh mass spectrum, density, comparison to quasars.

• Emerging developments – – a theory– Extension to very low masses– spins– Possibility of gravitational wave observation of BH mergers.

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 ~ 1011 suns.• Objects the size of the solar system that outshine the galaxy.

• Quasars were populous in the youthful universe, but are rare now.

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.

Inverse dinosaur problem

• The light radiated by quasars is proportional to mc2 of accreted matter.

• The mass of order m of the accreted matter.

• The density of quasars mandates a density of bh of about 2 x 105 solar masses/Mpc3.

• Where are the relics?

Circular and parabolic orbits

M84

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.

NGC 4258

• NGC 4258 Maser mass is

3.9 107 at this distance.

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 - 2.5x105 Msun/Mpc-3 for h=.65 (Yu & Tremaine)

- 4.8x105h2 Msun/Mpc-3 (Aller & Richstone)

- consistent results from different datasets.

- S = 2.2x105 Msun/Mpc3

A note on backgrounds

• Any background can be expressed in terms of the cosmic microwave background energy density (about 1eV/cm3).

• Backgrounds (other than the CMB) can be seen as integrals of source counts.

• uqso ~ 10-4

bh ~ uqso-1(1 - )(1 - fgw – fejections)

Only gas will produce the correct Soltan number

• Accreting matter: – Stars– Degenerate objects– Dark matter– Gas

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?

Thermodynamics of the protogalaxy

• QSO emits Xrays: 0.1*m.c2 in 108yr• Galaxy has stars: 0.01*Mc2 in 1010yr

• QSO light/starlight ~ 103 m./M ~ 1• bh is as important as stars in early phases of

galaxy.

LISA sky

Grav waves.