The Once and Future CMB DOE, Jan. 2002 Wayne Hu
The On(c)e Ring
Original Power Spectra of Maps 64º Band Filtered
Ringing in the New Cosmology
Gravitational Ringing Potential wells = inflationary seeds of structure Fluid falls into wells, pressure resists: acoustic oscillations
Successes & Surprises Confirmed Inflationary Predictions
Successes & Surprises Confirmed Inflationary Predictions Initial curvature perturbations Harmonic peak relation
Successes & Surprises Confirmed Inflationary Predictions Initial curvature perturbations Harmonic peak relation Nearly scale-invariant amplitude Slope of power spectrum
Successes & Surprises Confirmed Inflationary Predictions Initial curvature perturbations Harmonic peak relation Nearly scale-invariant amplitude Slope of power spectrum Spatially flat universe Angular location of the Peaks
Successes & Surprises Confirmed Inflationary Predictions Initial curvature perturbations Harmonic peak relation Nearly scale-invariant amplitude Slope of power spectrum Spatially flat universe Angular location of the Peaks [Baryon density consistent with BBN] [Dark matter detected; consistent with local]
Successes & Surprises Confirmed Inflationary Predictions Initial curvature perturbations Harmonic peak relation Nearly scale-invariant amplitude Slope of power spectrum Spatially flat universe Angular location of the Peaks [Baryon density consistent with BBN] [Dark matter detected; consistent with local] Implies Missing Energy Flat universe implies critical density ~3x the dark matter density Dark energy composes ~2/3 of total
Spatial Curvature Physical scale of peaks = distance sound travels Angular scale measured: comoving angular diameter distance test for curvature Flat Closed
Curvature in the Power Spectrum Angular location of harmonic peaks Flat = critical density = missing dark energy
Back to the Future
Dark Energy and Inflation What is the dark energy a cosmological constant? an ultra-light scalar field?
Dark Energy and Inflation What is the dark energy a cosmological constant? an ultra-light scalar field? Equation of state w=p/r Clustering properties c s =dp/dr 2
Dark Energy and Inflation What is the dark energy a cosmological constant? an ultra-light scalar field? Equation of state w=p/r Clustering properties c s =dp/dr What is the energy scale and particle physics of inflation? 2
Dark Energy and Inflation What is the dark energy a cosmological constant? an ultra-light scalar field? Equation of state w=p/r Clustering properties c s =dp/dr What is the energy scale and particle physics of inflation? Gravitational wave contribution µ E 4 2
Dark Energy and Inflation What is the dark energy a cosmological constant? an ultra-light scalar field? Equation of state w=p/r Clustering properties c s =dp/dr What is the energy scale and particle physics of inflation? Gravitational wave contribution µ E 4 Integrated Sachs-Wolfe (ISW) effect and secondary anisotropies 2
Dark Energy & Potential Decay Dark energy does not cluster on galactic scale
Dark Energy & Potential Decay Dark energy does not cluster on galactic scale A smooth component contributes density r to the expansion but not density fluctuation dr to the Poisson equation
Dark Energy & Potential Decay Dark energy does not cluster on galactic scale A smooth component contributes density r to the expansion but not density fluctuation dr to the Poisson equation Potential to decay when dark energy dominates Scalar field smooth out to the horizon scale (sound speed cs=1)
Dark Energy & Potential Decay Dark energy does not cluster on galactic scale A smooth component contributes density r to the expansion but not density fluctuation dr to the Poisson equation Potential to decay when dark energy dominates Scalar field smooth out to the horizon scale (sound speed cs=1) Potential decay direct astrophysical detection of dark energy and probes its particle properties
Scalar ISW Effect Gravitational redshift photon energies Metric stretching photon wavelengths [generalizes to gravitational waves tensor metric] Cancellation on small scales
Scalar ISW Effect Gravitational redshift photon energies Metric stretching photon wavelengths [generalizes to gravitational waves tensor metric] Cancellation on small scales
Dark Energy in the Power Spectrum ISW effect kicks in at large scales and high w At low w, cross-correlate with dark matter CMB lensing: %-level w, horizon scale smoothness
Gravitational Wave ISW Quadrupolar (transverse-traceless) stretching of metric leaves large-scale ISW imprint Degenerate in temp.; distinct in polarization
Polarization Thomson scattering of quadrupolar anisotropy generates linear polarization Symmetry properties of density vs. gravitational wave perturbations distinguish pattern
Unique Signature of Inflation? Gravitational lensing also generates B-polarization and must be modelled and subtracted 100 10 reionization QE T (mk) 1 EE BB 0.1 0.01 Hu & Dodelson (2001) gravitational waves 10 100 1000 l (multipole) gravitational lensing Power spectra of scalar (E) piece pseudoscalar (B)
Perfect Statistical Modelling Even with perfect statistical modelling, lensing prevents detection if E<10 16 GeV Requires study of lensing and better subtraction 3 E i (10 16 GeV) 2 1 Planck Ideal MAP Hu (2001); Hu & Dodelson (2001) 1 1.05 1.1 n
Summary Current measurements strongly support the inflationary paradigm and missing dark energy
Summary Current measurements strongly support the inflationary paradigm and missing dark energy Future of the CMB: secondary anisotropies and polarization
Summary Current measurements strongly support the inflationary paradigm and missing dark energy Future of the CMB: secondary anisotropies and polarization Identify the equation of state of the dark energy Particle nature (clustering) of the dark energy Energy scale of inflation
Summary Current measurements strongly support the inflationary paradigm and missing dark energy Future of the CMB: secondary anisotropies and polarization Identify the equation of state of the dark energy Particle nature (clustering) of the dark energy Energy scale of inflation Goals intimately tied to lensing of the CMB... Hu (2001a); Hu (2001b); Hu (2001c); Hu & Dodelson (2001); Hu & Okamoto (2001); Hu & Krastov (2002)