Seeing the Earliest Photons: the CMB from Bell Labs to Planck Andrew Jaffe Courtesy Charles Lawrence TAUP 2009 1 July Thursday, 9 July 2009
Seeing the Earliest Photons: the CMB from Bell Labs to Planck □ The history and physics of the CMB □ Primordial fluctuations □ Observing the fluctuations ■ from space — COBE, WMAP ■ and earth — Boomerang, MAXIMA, ... □ A standard cosmological model? □ Or important anomalies? □ Next: Planck, EBEX, Polarbear Thursday, 9 July 2009
The First Picture of the CMB • Penzias & Wilson, 1965 Thursday, 9 July 2009
The First Picture of the CMB • Penzias & Wilson, 1965 Thursday, 9 July 2009
Black Body radiation from the Early Universe Penzias & Wilson Mather et al, 1994 Thursday, 9 July 2009
Black Body radiation from the Early Universe Penzias & Wilson Mather et al, 1994 Thursday, 9 July 2009
Black Body radiation from the Early Universe Al Kogut, ARCADE, http://arcade.gsfc.nasa.gov/cmb_spectrum.html Thursday, 9 July 2009
History ■ 1948: Alpher, Gamow, Herman predict the existence of the CMB ■ 1964: Dicke, Peebles, Roll & Wilkinson (Princeton) start looking ■ 1964: Penzias & Wilson (AT&T Bell Labs) accidently find it T = 3K , constant over sky □ ■ 1969-70s: 0.1% variations Doppler Shift from our motion through the CMB □ ■ 1990s: 10 -5 variations Sign of the large-scale structure of the universe at early times □ Thursday, 9 July 2009
The Cosmic Microwave Background □ 400,000 years after the Big Bang, the temperature of the Universe was T ~10,000 K □ Hot enough to keep hydrogen atoms ionized until this time □ proton + electron → Hydrogen + photon [ p + + e - → H+ γ ] □ charged plasma → neutral gas □ Photons (light) can't travel far in the presence of charged particles □ Opaque → transparent W. Hu Thursday, 9 July 2009
Cosmological Horizons Physics works at the speed of light: No “causal influence” from more than Horizon distance d H = (age of universe) × (speed of light ) [Sound] horizon at LSS ~1° Oscillations in primordial plasma ( sound waves) In the standard big bang, the horizon always grows But here’s what Penzias & Wilson saw: T = 3K, ~constant over sky How did everything get to be the same temperature???? Thursday, 9 July 2009
Inflation □ Expand the universe by a factor >>10 30 at t ~10 -30 sec. ■ a ∝ e Ht □ Makes the universe flat ( Ω =1 ) □ Puts it all into “causal contact” (so the CMB can be isotropic) □ Generates perturbations that become galaxies, clusters, etc. ■ QM perturbations in primordial fields ■ scalar — density perturbations ■ tensor — gravitational radiation □ But: no way yet to choose among specific models within particle physics, string theory, relativity Thursday, 9 July 2009
What affects the CMB temperature? Initial temperature (density) of the photons □ Cooler Hotter Doppler shift due to movement of baryon-photon plasma □ Gravitational red/blue-shift as photons climb out of potential wells or fall off of □ underdensities Photon path from LSS to today □ All linked by initial conditions ⇒ 10 -5 fluctuations □ Thursday, 9 July 2009
What affects the CMB temperature? Initial temperature (density) of the photons □ Cooler Hotter Doppler shift due to movement of baryon-photon plasma □ Gravitational red/blue-shift as photons climb out of potential wells or fall off of □ underdensities Photon path from LSS to today □ All linked by initial conditions ⇒ 10 -5 fluctuations □ Thursday, 9 July 2009
What affects the CMB temperature? Initial temperature (density) of the photons □ Cooler Hotter Doppler shift due to movement of baryon-photon plasma □ Gravitational red/blue-shift as photons climb out of potential wells or fall off of □ underdensities Photon path from LSS to today □ All linked by initial conditions ⇒ 10 -5 fluctuations □ Thursday, 9 July 2009
What affects the CMB temperature? Initial temperature (density) of the photons □ Cooler Hotter Doppler shift due to movement of baryon-photon plasma □ Gravitational red/blue-shift as photons climb out of potential wells or fall off of □ underdensities Photon path from LSS to today □ All linked by initial conditions ⇒ 10 -5 fluctuations □ Thursday, 9 July 2009
Fluctuations in the CMB Inflation??? Thursday, 9 July 2009
Describing the (CMB) Universe x ) − ¯ T (ˆ ≡ ∆ T T � T (ˆ x ) = a ℓ m Y ℓ m (ˆ x ) ¯ T ℓ m “Fourier transform” on a sphere □ Allows us to define the power spectrum , C l � a ∗ ℓ m a ℓ ′ m ′ � = δ ℓℓ ′ δ mm ′ C ℓ ■ Assumes isotropy (no absolute orientation) ■ If we also assume Gaussianity (e.g., inflation): � � | a ℓ m | 2 1 − 1 P ( a ℓ m | C ℓ ) = exp √ 2 π C ℓ 2 C ℓ Thursday, 9 July 2009
Theoretical Predictions Mean square fluctuation amplitude ~180 ° /Angular scale Thursday, 9 July 2009
CMB Anisotropy Experiments ■ 1989-1993: COBE/DMR ( NASA ) ■ Full-sky, 7° beam (much larger than ~1° horizon) ■ Early 1990s: Small-scale Experiments ■ balloon & ground-based, ~1° beam 1990s-2000s: 2 nd generation MAXIMA/BOOMERANG, DASI/CBI, VSA, Archeops, ACBAR, QUaD ■ 2003+: WMAP (NASA): New Results ■ May 2009++: Planck Surveyor (ESA) ■ 2000-10s: 3 rd generation experiments (B-Modes) ■ SPIDER, Polarbear, EBEX, Clover Thursday, 9 July 2009
January, 2003 Thursday, 9 July 2009
WMAP! Thursday, 9 July 2009
Measuring Curvature with the CMB Flat Ω =1 Us! Last Scattering Surface Thursday, 9 July 2009
Measuring Curvature with the CMB Closed Ω > 1 Us! Last Scattering Surface Thursday, 9 July 2009
Measuring Curvature with the CMB Open Ω < 1 Us! Last Scattering Surface Thursday, 9 July 2009
Thursday, 9 July 2009
WMAP's orbit Thursday, 9 July 2009
WMAP and other data Thursday, 9 July 2009
WMAP and other data Thursday, 9 July 2009
Maps of the Cosmos DMR MAXIMA WMAP Thursday, 9 July 2009
Measuring the geometry of the Universe Amount of “dark energy” (cosmological constant) Flat Universe WMAP Ω tot = Ω m + Ω Λ Λ =1 Amount of “matter” (normal + dark) Thursday, 9 July 2009
Temperature and polarization from WMAP Thursday, 9 July 2009
The Polarization of the CMB Anisotropic radiation field at last scattering → polarization Temperature (determined by params) “Grad” or E mode Breaks degeneracies New parameters: reionization E-Mode Pol “Curl” or B sensitive to (determined by params) gravity waves “Smoking gun” of inflation? Very low amplitude B-Mode Pol Need better handle on (depends on inflation) systematics, and... Polarized foregrounds? DASI MAXIPOL, B2K MAP E B B E Planck Future satellites? Thursday, 9 July 2009
Temperature Temperature/ E-Polarization E-Polarization B- Polarization Thursday, 9 July 2009
CMB Measurements: State of the Art Chiang et al 2009 Thursday, 9 July 2009
The “unified” spectrum c. 2008 Contaldi & Jaffe Thursday, 9 July 2009
A “Standard Cosmological Model” from the CMB? □ Largely confirms results from COBE, MAXIMA, BOOMERANG, etc. ■ Flat Universe ( Ω =1 ) 23% Dark Matter □ 4% Normal Matter □ 73% “Dark Energy” (accelerating the expansion) □ ■ Initial seeds consistent w/ Inflation ■ Hubble constant 72 km/s/Mpc □ Details depend on “priors” (irrevocably: feature, not bug…) Thursday, 9 July 2009
Anisotropy (from topology?) □ Low power at large scales? □ Problem becomes more acute beyond the power spectrum □ Multi-connected topology? □ Finite universe ■ Cutoff at large scales induces power deficit ■ In closed universe cutoff determined by curvature alone □ Intrinsic anisotropy (orientable manifolds) ■ Possible apparent non-Gaussianity □ Effects only present at large scales – at smaller scales standard Λ CDM power spectrum recovered □ (Luminet et al “Soccer Ball” [Dodecahedron/Poincaré] universe?) Thursday, 9 July 2009
Anisotropy (from topology?) □ Low power at large scales? □ Problem becomes more acute beyond the power spectrum □ Multi-connected topology? □ Finite universe ■ Cutoff at large scales induces power deficit ■ In closed universe cutoff determined by curvature alone □ Intrinsic anisotropy (orientable manifolds) ■ Possible apparent non-Gaussianity □ Effects only present at large scales – at smaller scales standard Λ CDM power spectrum recovered □ (Luminet et al “Soccer Ball” [Dodecahedron/Poincaré] universe?) Thursday, 9 July 2009
Topology in a flat “universe” Don’t need to “embed” the square to have a connected topology. “tiling the plane” Thursday, 9 July 2009
Topology + geometry □ Tile the 2-sphere with different fundamental domains □ Harder to visualize in 3-d: Thursday, 9 July 2009
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