1
Q
CMB Characteristics
A
- Isotropic
- Black-Body Radiation
- TCMB = 2.73 ± 0.06 K
2
Q
Interpretation of CMB
A
- Redshifted radiation from hot big bang
- Universe expanding and cooling
3
Q
Energy Density of Background Radiation
A
ρRc² = aBT⁴, where aB is the radiation constant
4
Q
Relation Between Energy Density and Scale Factor
for radiation
A
ρR = ρR,0 (a0/a)⁴
5
Q
Temperature Evolution of CMB (proportionality relation)
A
TCMB ∝ 1/a
6
Q
Friedmann Equation for Flat Universe
A
adot = a0²/a √(8πGρR,0/3)
i think we can derive this if we just plug in k=0 into the original equation and using the radiation density as a function of a
7
Q
Temperature Evolution of the Early Universe (temperature as a function of time)
A
- T = (3c²/32πGaB)¼ t⁻½
- T[K] = 1.52×1010/√t[s]
8
Q
Hubble Constant
A
H0 = 71 km/(s Mpc)
9
Q
Energy Densities in the Universe
A
- Ωb ≈ 0.05 (baryonic)
- Ωd ≈ 0.25 (dark matter)
- ΩΛ ≈ 0.7 (dark energy)
10
Q
Current Values for Densities (critical and dark)
A
- Critical density: ρc,0 ≈ 1 · 10-26 kg/m³
- Dark matter density: ρd,0 ≈ 2.5 · 10-27 kg/m³
11
Q
Dark Matter
A
- Galactic rotation (MW) -> DM in halo
- Mass luminostiy relation of galaxy clusters (mass through virial theorem)
- Gravitational lensing
- Map with CMB
