thing invisble to see: supermassive black holes douglas richstone university of michigan
TRANSCRIPT
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.