Dark matter and black holes over cosmic time

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Dark matter and black holes over cosmic time
TOMMASO TREU
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Our view of the Universe (2009)
Now wear your dark matter goggles!!
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Elliptical Galaxies. Simple?
MOVIE
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A big dark surprise

• They contain supermassive black holes at their
  centers.
• The mass of the black hole is proportional to
  that of the stars in the galaxy and that of the
  dark matter around it!
• MBH 0.2 M 0.001 MDM

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The local Universe
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are thought to form by mergers of spirals
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Questions and puzzles

1. Do elliptical galaxies live in dark matter halos
   consistent with those predicted by the model?
2. Why is the mass of the black hole proportional to
   the mass of the stars and that of dark matter?
3. How do (stars) black holes and dark matter evolve
   over cosmic time?

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Telescopes as time machines
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Into the invisible

• How do we see dark matter?
• Gravitational lensing
• How do we weigh black holes?
• Reverberation mapping

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What is Gravitational Lensing?Matter curves
space
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What is Gravitational Lensing?and can create
multiple images
Image separation is a direct measurement of mass,
luminous or dark!
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Why is it called Lensing?
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A DOUBLE EINSTEIN RING
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A DOUBLE EINSTEIN RINGGEOMETRY
OUTER RING (11 billion light yrs)
MAIN LENS (2 billion light yrs)
OBSERVER
INNER RING (6 billion light yrs)
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How likely?

• More unlikely than winning two consecutive bets
• on a single number at roulette!

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The most precise mass density profile measurement

Dark matter halo!
(Atoms)
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Really? Is there dark matter?
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Cosmic collisions and dark matter
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Black holes on a scale?
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Reverberation Mapping
Ring of gas with radius r Gas along line of
sight to observer will appear to respond with no
delay Gas that is furthest from observer will
appear to have response delayed by 2r/c
Mean lag time is r/c, I.e radius / speed of light
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Example Arp 151
SDSS
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The local Universe
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Summary

• Our standard cosmological model is undergoing
  rigorous testing
• We need to understand how galaxies and black
  holes form
• Things that appear to work include
• Galaxies live in dark matter halos.
• Dark matter appears to be real although it would
  be good to know what particle it is made of
• Things that we do not understand include
• Why are galaxies isothermal?
• How do black holes know of their host galaxy and
  viceversa?
• The most massive galaxies and their black holes
  appear to have completed their evolution before
  the lower mass systems. In the model we naively
  expect the opposite.
• Is the model fundamentally wrong or is this
  because we do not understand the gastrophysics?

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The end