DARK MATTER AND GALAXY FORMATION

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DARK MATTER AND GALAXY FORMATION
ILIAS 2006

Joe Silk

University of Oxford
IAP,
December 2006
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DARK MATTER IN GALAXIES AND CLUSTERS
Klypin et al
rotation velocity
THE MILKY WAY
GALAXY CLUSTERABELL 1689
distance from centre of galaxy in kpc
Sofue and Rubin
NON-BARYONIC DARK MATTER DOMINATES!
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SUCCESS OF LARGE-SCALE STRUCTURE
THE DARK SIDE OF GALAXY FORMATION
Millennium simulation 2005
Dark matter
Luminous matter
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MILLENNIUM SIMULATION
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• THE MILKY WAY HALO

Diemand and Madau 2005
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STEEPNESS OF COLD DARK MATTER DENSITY PROFILES
COMPARED WITH THE ROTATION CURVE OF A LOW
SURFACE BRIGHTNESS DWARF GALAXY
rotation velocity
density profile

• distance from centre of galaxy in kpc

McGaugh, Barker and de Blok 2003
Fukushige, Kawai and Makino 2004
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THE MILKY WAY HALO DWARF GALAXIES
orbital velocity
vp gt13 km/s
J. Taylor 2005
distance from centre of galaxy in kpc
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RESURRECTION VIA FUNDAMENTAL PHYSICS

• MODIFYING THE NATURE OF DARK MATTER?
• MODIFYING GRAVITY?

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MOND
EVEN ONE ROBUST EXCEPTION WOULD BE FATAL TO
MOND! and if there were more?
rotation velocity
distance from centre of galaxy in kpc
MOND fits are not always perfect!
NGC 3198

• NGC 2841

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The bullet cluster
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RESURRECTION VIA ASTROPHYSICS

• FEEDBACK FROM EXPLODING STARS AND OUTFLOWS FROM
  SUPERMASSIVE BLACK HOLES
• DYNAMICAL FEEDBACK

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THE EFFECTS OF SUPERNOVA-DRIVEN WINDS
vp gt 43 km/s
orbital velocity
J. Taylor 2005
distance from centre of galaxy in kpc
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Dynamical heating of CDM core
Couchman et al. 2006
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TIDAL DISRUPTION OF DWARF GALAXIES
40 kpc
P. Harding 2004
-40 kpc
40 kpc
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dark matter streams?
Freese et al. 2004
Law, Johnston and Majewski 2005
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WHERE ARE THE BARYONS?
Synthesis of light elements in first 3
minutes Cosmic microwave background temperature
fluctuations at 106 years Intergalactic gas
clouds at 109 years ALL GIVE Wbaryons0.04

• WHEREAS TODAY
• NONBARYONIC DARK MATTER Wmatter0.27
• STARS
  Wstars0.005
• BARYONS ARE 15 BUT STARS ARE ONLY 2!
• 80-90 OF THE BARYONS
• ARE IN THE INTERGALACTIC MEDIUM
• HOW DID THEY GET THERE?

Hydrogen lines in absorption against a distant
quasar
high z
X-ray absorption line
low z
Mrk 421
wavelength
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20 Mpc cube of IGM centered on a galaxy group
Oppenheimer and Dave 2006
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SHEDDING LIGHT ON COLD DARK MATTER
A MOTIVATED CANDIDATE FROM
SUPERSYMMETRY WEAKLY INTERACTING
MASSIVE PARTICLE OR WIMP
Interaction strength is determined by the relic
density SUSY breaking scale suggests WIMP mass
is in range 0.1-1 TeV
The Milky Way halo is a giant laboratory teeming
with WIMPs, about ten million per sq meter per
sec pass through the earth!
DIRECT DETECTION SO FAR HAS NOT SUCCEEDED

• HALO CLUMPINESS BOOSTS THE SIGNAL!

Minimum clump mass is 10-6 Msun m0.1TeV-2
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H. Zhao et al. 2005
Tidal disruption
Survival
Diemand et al. 2005
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Nearby clumps of CDM

• Cumberbatch and Silk 2006

PAMELA launch in 2006
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THE CASE FOR IMBHs IN POP III
Borys et al. 2006
Tumlinson 2006
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100s of pop III IMBHs are in the halo
How to detect the nearest IMBHs Xrays or
neutrinos from dark matter annihilations
Bertone 2006
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THE EFFECT OF AN IMBH ON HI AT z10
spin temperature
0.5Mpc
BH
no BH
DT
Kuhlen et al. 2005