Thing Invisble to See: Supermassive Black Holes

Douglas RichstoneUniversity of Michigan

Thanks to our sponsor

• 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 ~ 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.

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 105 solar masses/Mpc3.

• 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 - 2.5x105 Msun/Mpc³ for h=.65 (Yu &

Tremaine) - 4.8x105h² Msun/Mpc³ (Aller &

Richstone) - consistent results from different

datasets.- S = 2.2x105 Msun/Mpc3

- 6 – 9x105 (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/cm3).

• uqso ~ 10-4

bh ~ uqso-1(1 - -gw – ejections)• ustars ~ 1

Second parameter?

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

A taxonomy of theories for the M~v4 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~v4 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?

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

LISA sky

Grav waves.