Dark Matter, Dark Energy, and the Current State of Cosmology - PowerPoint PPT Presentation

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Dark Matter, Dark Energy, and the Current State of Cosmology

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Title: Dark Matter, Dark Energy, and the Current State of Cosmology


1
Dark Matter, Dark Energy, and the Current State
of Cosmology
  • Nick Kaiser
  • Institute for Astronomy
  • University of Hawaii

2
Fritz Zwicky
3
The Coma Cluster
4
Zwicky the Missing Mass
  • Measured galaxy speeds in Coma
  • Virial theorem M/L 500 M_sun/L_sun
  • The missing mass
  • An outstanding problem in cosmology
  • 90-98 of the universe is in a mysterious form
  • detectable only by its gravitational attraction

5
The Dark Matter Puzzle
  • Where is it?
  • How much is there?
  • What is it?

6
Cosmology in a nutshell
  • The old cosmology
  • Friedmann Einstein de Sitter .
  • The New Cosmology
  • Inflation - scalar fields
  • The Hot Big Bang
  • Structure Formation

7
The Friedmann Model
  • Scale factor R(t)
  • mass density and curvature of space
  • problems
  • horizon
  • flatness

8
Inflationary Cosmology
  • In the beginning there was the field.
  • Vector, tensor and scalar fields
  • Weinberg-Salaam
  • unified theory - the Higgs field
  • The inflaton
  • central to inflation
  • solves the old problems
  • predicts a flat universe ?1
  • quantum fluctuations ? structure formation

9
The Hot Big Bang
  • The cosmic kitchen
  • big bang nucleosynthesis
  • Abundance of baryons
  • ?baryons 0.02
  • Relics
  • cosmic background
  • neutrinos

10
Structure Formation
  • Quantum fluctuations
  • gravitational instability
  • dark matter
  • the cosmic web

11
The Cosmic Web
12
The history of the Universe
13
Inventory of Dark Matter
  • Galaxies
  • luminous parts ? M/L 1-5
  • flat rotation curves ? M/L 30
  • Pairs Groups Clusters
  • M/L 100-500
  • Super-Cluster Dynamics
  • ? ? 1?

14
Galaxies
15
Gravitational Lensing
  • Gravity bends light rays
  • probe of dark matter
  • highly versatile
  • microlensing - machos
  • galaxy lensing
  • lensing by cluster
  • lensing by superclusters

16
Theory of gravitational lensing
17
Lensing by galaxies
18
Lensing by clusters
19
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20
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21
MACSJ2243
22
Cosmic Microwave Background
  • Relic from the big bang
  • Probe of structure _at_ t 100,000 yr
  • COBE
  • large angle
  • BOOMERANG
  • small angles
  • flat Universe

23
COBE Satellite
24
The COBE Sky
25
From COBE to BOOMERANG
26
The Universe is flat!
27
What is the Matter?
  • Neutrinos?
  • No longer popular
  • Axions or other fields?
  • WIMPs?
  • Etc etc etc.
  • Plenty of theory - scarce observations

28
Dark Energy
  • Consensus model ? 0.3
  • CMB ? ? 1
  • resolution the accelerating Universe
  • expansion history from supernovae
  • fainter than expected
  • universe is being accelerated - dark energy
  • late time inflation - yet another field?

29
The Nearest Galaxies
LMC
February 22, 1987
SMC
30
Expansion History from SN
31
The Current Status of Cosmology
  • A working model for creation of the Universe
    and the structure therein
  • Impressive concordance with current observations
  • Embarrassing number of ingredients
  • luminous baryons dark baryons neutrinos dark
    matter dark energy.
  • Epicycles?
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