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Cosmology with CMB

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Size : 10-100 kilo parsec (kpc.) Mass : 100 billion Stars ... Isotropy around every point. implies. Homogeneity. Cosmological principle. FLRW models ... – PowerPoint PPT presentation

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Title: Cosmology with CMB


1
Cosmology with CMB LSS The Cosmological Model
ITP, Beijing, China 3rd Asian Winter School on
String Theory (Jan 12-17, 2009)
Tarun Souradeep
I.U.C.A.A, Pune, India
2
India
I.U.C.A.A., Pune, India
3
The Realm of Cosmology
Basic unit Galaxy
Size 10-100 kilo parsec (kpc.) Mass 100
billion Stars
Measure distances in light travel time 1 pc.
(parsec) 200,000 AU
3.26 light yr. Measure Mass in
Solar mass
Andromeda Galaxy
4
The Realm of Cosmology
Galaxy Clusters
Size Mega parsecs (Mpc.) Mass 100 1000
Galaxies (5 luminous, 15 hot gas, 80dark
matter !)
Coma cluster
5
The Realm of Cosmology
Super Clusters
Size 10 Mega parsecs Mass few 1000
Galaxies
Perseus super cluster
6
The Realm of Cosmology
Distant galaxies beyond a cluster .
7
The Realm of Cosmology
most distant galaxies
Hubble deep field
8
The Realm of Cosmology
100 million Light years
9
The Realm of Cosmology
100 million Light years
10
The Realm of Cosmology
500 million Light years
11
The Realm of Cosmology
Few billion parsecs
2dF Galaxy Redshift Survey
12
The Realm of Cosmology
Few billion parsecs
SLOAN DIGITAL SKY SURVEY (SDSS)
13
The Realm of Cosmology
14
The Realm of Cosmology
15
How can we even hope to comprehend this immensely
large complex Universe !?!
Look for an appropriate simple model
16
The Isotropic Universe
Distribution of galaxies on the sky is broadly
isotropic
  • Isotropy around every point
  • implies
  • Homogeneity
  • Cosmological principle
  • FLRW models

South
North
Lick Observatory survey
17
The Isotropic Universe
Cosmic Microwave Background
Nobel prize 1978
Serendipitous discovery of the dominant
Radiation content of the universe as an
extremely isotropic, Black-body bath at
temperature T02.725 (/-0.002)K . Clinching
support for Hot Big Bang model
18
Cosmic Microwave Background
The dominant radiation component in the universe
400 CMB photons per cubic cm.
(D. Scott 99)
19
Cosmic Microwave Background
The most perfect Black-Body spectrum in nature
COBE FIRAS
The CMB temperature A single number characterize
s the radiation content of the universe!!
COBE website
20
The Expanding Universe
Einsteins General relativity applied to an
uniform distribution of matter on cosmic scales
leads to a smooth expanding universe
21
Expanding Universe
Hubbles law Recession velocity of galaxies is
proportional to the distance
Hubbles measurements in 1929
Frequency of light from a distant galaxy ?
Redshift, zv/c Redshift is related to distance
Fig. Ned Wright
22
Expanding Universe
Hubbles Law Current observational status
Fig. Ned Wright
23
The Expanding Universe
Leads to the Hubbles law Recession velocity is
Proportional to the distance
Fig. Ned Wright
24
Geometry of the Universe
Spherical Universe Constant positive curvature
Hyperbolic Universe Constant negative curvature
Flat Universe
25
Geometry, Expansion Matter
26
Space-time of the cosmos
Fig. Ned Wright
27
Space-time of the cosmos
Fig. Ned Wright
28
Space-time of the cosmos
General relativity allows us to formulate
physics in any coordinates
Fig. Ned Wright
29
Space-time of the cosmos
Comoving spatial coordinates
Fig. Ned Wright
30
Space-time of the cosmos
Conformal time
Comoving spatial coordinates
Fig. Ned Wright
31
Cosmological Redshift
Observer
Distant galaxy
Equal time events at a distant galaxy appears
time-dilated
Frequency of light from a distant galaxy is
scaled by the expansion ? Redshift,
zv/c Redshift is related to distance
Fig. adapted from Ned Wright
32
Dust in an expanding box
Size ¼ Number density x 64 Energy density x 64
Expansion implies Hot early universe Smaller gt
hotter
Size ½ Number density x 8 Energy density x 8
time
Radiation in an expanding box
Size ¼ Number density x 64 Energy density x
128 Temperature x 4
Size ½ Number density x 8 Energy density x
16 Temperature x 2
time
33
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34
Cosmic SuperIMAX theater
0.5 Myr
14 GPc
Here Now (14 Gyr)
Transparent universe
Opaque universe
35
Standard cosmological model Geometry,
Expansion Matter
Clustering matter
Non-Clustering matter
36
How much do we now know about this model
Universe ?
lots !!!
37
Good old Cosmology, New trend !
Total energy density
Baryonic matter density
Dark energy density
Expansion rate of the universe
Dawn of Precision cosmology !!
Dark matter density
Age of the universe
NASA/WMAP science team
38
Matter budget of the Universe
Ordinary (baryonic) matter
FigNASA/WMAP science team
39
Where is the Cold Dark matter ?
Zwicky 1935
6 times more in dark matter than baryonic
matter
40
Ordinary matter is sprinkled on the Cold Dark
matter distribution
Galaxies light up at the densest points
41
Rotation of Spiral Galaxies !!!
42
Dark matter in Galaxies !
R
43
Dark matter in our own backyard !?!
44
Dark matter in the Milky way
45
Dark matter in other galaxies too !!
46
Dark matter in clusters !?!
47
Speeding galaxies in a cluster
Marbles in a glass bowl !!! Velocity dispersion
of galaxies in a cluster Measures the depth of
its gravitational potential
48
Hot gas in clusters
Coma cluster
49
Hot gas in clusters
Virgo cluster
50
Gravitational lensing
Distant galaxies beyond a cluster are
lensed.
51
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52
Bullet cluster
53
Bullet cluster
movie
54
Evidence for Dark Energy?
Is it the Cosmological constant? The Cosmic
repulsive force Einstein once proposed and later
denounced as his biggest blunder ?
55
Geometry, Expansion Matter
Dark energy causes accelerated expansion
56
Correction to the Hubbles Law
Measure distances independent of redshift
v/c till v/cz1
. measures the acceleration in the expansion
of the universe
57
Measuring distance using standard candles
10 m
Flux
4 Flux
5 m
58
Supernova in a galaxy standard candle
59
Supernova can be seen in distant galaxies
60
Supernova in a very distant galaxy
61
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62
How much do we now know about this model
Universe ?
How do we know so much now about this model
Universe ?
63
  • Accelerated expansion of the universe (High
    redshift SN)
  • Structure formation scenario compatible with
    observations

Matter budget of the cosmos
  • Rotation of galaxies
  • Speeding galaxies in clusters
  • Gravitational lensing
  • Hot gas in clusters
  • Light elements from early hot universe
  • Low CMB temperature fluctuations
  • Starlight from Galaxies
  • Stuff we are made of!!

FigNASA/WMAP science team
64
Thank you !!!
Music of the Cosmic Drum
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