Inflationary Cosmology theory and evidence

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Inflationary Cosmology- theory and evidence
S.Mohanty
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What is known about the Universe

• Universe is expanding Hubbles Law
• Synthesis of light elements (He-Li)
• Big-Bang nucleosynthesis.
• Cosmic microwave background anisotropies.
• Inflation ?

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Expansion of the Universe- Hubbles Law
From the Proceedings of the National Academy of
SciencesVolume 15 March 15, 1929 Number 3 A
RELATION BETWEEN DISTANCE AND RADIAL VELOCITY
AMONG EXTRA-GALACTIC NEBULAE By Edwin Hubble
Velocity H x Distance
H 464km/s/Mpc
Age of Universe 2Gyr
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Expanding Universe with Supernovae
Type I SN Reiss et al (1996)
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Cosmological constant from supernovae
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Big Bang Nucleosynthesis
The Universe is made of 75 H and 24 He
The ratio of number of baryons (p,n) to photons is
h
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Big Bang Nucleosynthesis
Big Bang Nucleosynthesis
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Main steps in He formation
Weak interactions freeze out at 1 sec,T1
MeV. (n/p)Exp(-D/T) 1/6 with D1.293 MeV.
Neutron decay with half-life of 615 secs,
decreases the (n/p) ratio to 1/7 by the time of
deuterium formation.
Helium fraction
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Discrepancy between CMB and BBN values of h.
B D Fields and S.Sarkar (2004)
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Cosmic microwave background radiation
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Temperature maps
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Velocity of earth w.r.t CMB is V368(/- 2)km/s
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COBE (1993) , WMAP( 2003)
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Temperature anisotropy
Multipole expansion
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CMB anisotropy experiments
Wayne Hu
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Curvature of the Universe with CMB anisotropy
WMAP
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Max Tegmark
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Larger baryon number increases the acoustic peak
Wayne Hu
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Perturbations increase at larger distances due to
neutrino free-streaaming
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Polarization of CMBR
CMB Anisotropy
Wayne Hu
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Universe was re-ionised at z20
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Why is Inflation needed
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Travel back in time with the CMB photon
WMAP/NASA
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Why do we need Inflation?
We get a scale invariant density
perturbations which seed the formation of
structure like galaxies. (Bonus)
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Particle Horizon
Ned Wright
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Spacetime Metric of the expnding Universe
Horizon
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During inflation perturbations leave the horizon
and re-enter in radiation or matter era
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Permanent Horizon particles from vacuum

Inflation expands small quantum fluctuations into
classical particles Inflation theory explains
scale invariant density perturbations which seed
formation of galaxies.

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Inflation predicts a scale invariant density
perturbation spectrum
Harisson-Zeldovich spectrum
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Quantum fluctuations eventually end up as
structure of the universe like galaxies and
clusters
http//cosmicweb.uchicago.edu/filaments.html
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Density perturbations in LSS appear as
anisotropies in CMB
Einsteins equations density perturbations to
metric perturbations.
Temperature of CMB photon red-shifts as it climbs
out of the gravitational potential in LSS .
(Sachs Wolfe 1967)
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Role of the hot-big bang in Inflation
(K.Bhattacharya , R.Rangarajan, SM)
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Results Thermal effects of early Universe are
measurable in the CMB anisotropy
Universe at the Planck time can effect the CMB
spectra.
Inflation is the only window (so far) for
observing Planck scale physics.