Dark Energy Effects on CMB & LSS
The 2nd KIAS Workshop on
Cosmology and Structure Formation
Seokcheon (碩天 large sky) Lee
Institute of Physics,
Academia Sinica
SEP.20-21.2006.KIAS
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Outline
 Observable Impact of DE
 BAO, CL, SN, WL
 (Im)Perfect Dark Energy Fluid
 Effects on CMB and Matter Power Spectrum
 Summary
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Observable Impact of DE
 Modification of z–d relation
: Baryon Acoustic Oscillations (BAO, R.Kron),
SuperNova (SN, G-C Liu), [δD]
 Effects on growth of structures
: Galaxy CLustering counting (CL, Z.Zheng),
Weak Lensing (WL, Sejong Univ),
ISW effect (C.G.Park)
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Observations & Measurements
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H(z) & δ(z)
 Evolution of Background
 From WMAP data we
can find zeq ~ 5000
 Flat Universe is preferred
by WMAP. i.e. Ωk = 0
 Density fluctuation on
small scales (sub-horizon
scale)
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r(z) and dV(z)
 FRW metric
 Volume element
 Proper distance
 Comoving coordinate
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Imperfect DE Fluid
 Cosmological fluid
 Adiabatic and entropic
sound speed (J-C Hwang)
 Dark energy rest frame
 Anisotropic stress of DE
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Effects of σ on δ & θ
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SEP.20-21.2006.KIAS
For large scale source term :
-(1+ω)(c_s^2-ω)θ/k^2
ω = -0.8
Dominate metric source term
and derive δ to smaller values
k = 1.3 · 10^{-4} Mpc^{-1}
(c_s^2, c_vis^2) = (0,0),
(0.6,0),(0,0.6),(0.6,0.6)
δ gets smaller when DE
dominate (solid lines)
Θ increases (dashed lines)
ISW id enhanced as c^2
increases
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ISW Effects
 C_{vis}^2 : 1.0, 0.1, 0.01,
0.001, 0
 MD : total density grows in
order to Φ,Ψ = const.
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Matter Power Spectrum
 C_{vis}^2 = 1.0
 Solid line : w=-1.2,
c_s^2=1.0
Dash-dotted : w=0.8,c_s^2=0
Dashed : w=-1.2 c_s^2=0
Thick : w=-0.8, c_s^2=1.0
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Summary
 As c_{vis}^2 ↑, δ↓ , θ↑, H/k^2(1+ω)θ↑
 As c_{vis}^2 ↑, ISW ↑
 Effects on MPS occurs only at large scales
 CMB’s only sensitive to <ω>
 Correlation to others BAO, CL, D(g), WL…
 Bispectra (? Y. Suto)
 DARK ENERGY IS NOWHERE!
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