The Cosmic Microwave Background. Lecture 1 Elena Pierpaoli . (Cosmic Microwave Background). Brief History of time. Properties: isotropy and anisotropies. The CMB radiation is isotropic We are moving with respect to the CMB rest frame
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Brief History of time
Measuring the Fundamental Properties of the Universe
CMB - Cosmic Microwave Background
(Temperature and Polarization)
DT(q,f) = S al,m Yl,m (q,f)
cl = Sm |al,m|2
d (x) = dr/r (x)
d (k) = FT[d (x)]
P(k) = < |d (k)|2>
Pgal(k) = b2 P(k)
Nolta et al 08
Cold dark amtter
Ma & Bertschinger 95
Seljak & Zaldarriaga 06
Due to parity symmetry of the density field, scalar perturbations
Have U=0, and hence only produce E modes.
If there is no U mode to start with, scattering does not generate it. No B mode is generated.
Scattering sources polarization through the quadrupole.
Parity and rotation symmetry are no longer satisfied.
B modes could be generated, along with T and E.
Scattering only produces E modes, B
Are produced through coupling with E
And free streaming.
Tensor to scalar ratio r=1
Fluctuation on scale enters the horizon
Expan. factor a
Neutrinos do not free-stream
(I.e. behave like Cold Dark Matter)
(T=0.25 eV)1)Neutrino mass: Physical effects
Recombination2) The relativistic energy density Nn
Nn = (rrad - rg) / r1n
Before WMAP: N <17
After WMAP:N< 6.6
(Pierpaoli MNRAS 2003)
Bell, Pierpaoli, Sigurdson 06