discovery (1965): hot big bang
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Discovery (1965): Hot Big Bang. Anisotropies (1992): Structure Formation. Acoustic Peaks (1998-2003): Inflation. Detailed Acoustic Peaks (2003-12): Cosmological Parameters Dark Matter & Dark Energy. Why peaks and troughs?. - PowerPoint PPT PresentationTRANSCRIPT
Discovery (1965): Hot Big Bang
Anisotropies (1992): Structure Formation
Acoustic Peaks (1998-2003): Inflation
Detailed Acoustic Peaks (2003-12): Cosmological Parameters
Dark Matter & Dark Energy
Why peaks and troughs?
• Vibrating String: Characteristic frequencies because ends are tied down
• Temperature in the Universe: Small scale modes begin oascillating earlier than large scale modes
Puzzle: Why are all modes in phase?
Power on a given scale is averaged over multiple modes with same wavelength.
We implicitly assumed that every mode started with zero velocity.
If they do all start out with the same phase …
Time/(400,000 yrs)
First peak will be well-defined
Clum
pine
ss
As will first trough ...
And all subsequent peaks and troughs
Clu
mp
iness
Time/(400,000 yrs)
If all modes are not synchronized though
First “Peak” First “Trough”
We will NOT get series of peaks and troughs!
Time/(400,000 yrs)Time/(400,000 yrs)
Clum
pine
ss
Clum
pine
ss
Coherent Peaks and Troughs Evidence for Inflation
Keisler et al. 2011
Evidence for New Physics
• Total matter density is much greater than baryon density non-baryonic dark matter
• Total matter density is much less than total density dark energy
Discovery (1965): Hot Big Bang
Anisotropies (1992): Structure Formation
Acoustic Peaks (1998-2003): Inflation
Detailed Acoustic Peaks (2003-12): Cosmological Parameters
Dark Matter & Dark Energy
What’s next?
What’s Next?
• Physics Driving Inflation• Neutrino Masses and Abundances• Nature of Dark Energy
Non-Gaussianity
)%95(631
)%95(804
CLf
CLf
NL
NL
Current observations
WMAPSDSS
Smith, Senatore, & Zaldarriaga (2009)Slosar et al. (2008)
205
53
NL
NL
f
f
Upcoming observations
PlanckDES
If local NG is found in the next decade, single field models of inflation will be falsified
Dozens of experiments going after B-modes
QUIET: Araujo et al. 2012
Ambitious Plans for the coming Decade
Gravitational Waves Elsewhere
Dodelson, Rozo, & Stebbins (2003)Sarkar et al. (2008)
Dodelson (2010)Masui & Pen (2010)
Book, Kamionkowski, & Schmidt (2011)
Primordial Gravitational Waves
also produce lensing B-modes. B-mode lensing
(call it ω) spectrum peaks on the largest
scales*
GW wave signal
Scalar leakage
Noise Estimate
*Might be good way to test for bubble collisions predicted by eternal inflation
Gravitational Waves Elsewhere
The same gravitational wave that sources polarization after reionization also
transforms the shapes of galaxies: these two signals are correlated!
Cross-Correlation is non-negligible
Depends on l and redshift of source
galaxies; might devise weighting scheme to
optimize signal. Detection would
eliminate systematics.
Additional Neutrino Species
WMAP
Damping Scale and Sound Horizon
Effect of adding extra neutrinos (Hou et al. 2011)
• H-1 goes down• Ratio of damping scale to sound
horizon goes up• Sound horizon is fixed so damping
scale goes up, gets larger• Suppression kicks in at lower l• Power spectrum in the damping
tails goes down
Power in the Tail of the CMB is (a little) low
Keisler et al. 2011
Current Constraints
SPT favors high Neff (as do other small scale CMB expeirments)
Preliminary SPT Spectrum
Look for tighter neutrino constraints and constraints on n’
Secondary Anisotropies
Scattering off electrons Gravitational Lensing
kSZ: ReionizationThermal SZ: Clusters, LSS Cosmic Shear
Cluster Lensing
Lensing of the CMB
Hu 2002
CMB photons from the last scattering surface are deflected (~few arcminutes) by coherent large scale structure (~few degrees)
Effect is not as dramatic in real maps, but estimators of non-Gaussianity extract projected gravitational potential
Lensing of the CMB
Primordial unlensed temperature Tu is re-mapped to
where the deflection angle is a weighted integral of the gravitational potential along the line of sight
Lensing of the CMB
Consider the 2D Fourier transform of the temperature
Now though different Fourier modes are coupled! The quadratic combination
would vanish on average w/o lensing. Because of lensing, it serves as an estimator for the projected potential
where
Lensing of the CMB
Atacama Cosmology Telescope
Das et al. 2011
ACT, a high resolution experiment, has detected lensing of the CMB and estimated the power spectrum of the lensing structures
Matter-only model predicts more structure
Lensing of the CMB
Sherwin et al. 2011
Lensing amplitude + primary acoustic peak structure provide evidence for acceleration from the CMB alone at 3.2 sigma
South Pole Telescope has detcted this at > 6-sigma
Van Engelen et al 1202.0546
Planck and then ACTPol & SPTPol will make 30- or
40-sigma detections within
the next few years. We are
approaching the lower limit of 0.05
eV!
Difference between massless spectrum and one
with 0.1 eV
Hall & Challinor 2012
Clusters and Dark Energy
• Cluster abundance depends on geometry (volume as function redshift) and growth of structure (exponentially sensitive to σ8): excellent probe of Dark Energy
• Key Systematic: Mass Calibration• CMB can help by observing: Thermal SZ Effect
(Small scatter between mass and SZ signal) and CMB-Cluster Lensing (Direct determination)
Sunyaev-Zel’dovich Effect
13,823 Clusters in SDSS 12.6 M pixels of 3.4’ size
Challenge: Large WMAP pixels
Sunyaev-Zel’dovich Effect
Non-parametric Average T in annuli around massive (blue) and less massive (red) clusters. Compare to predictions accounting for CMB noise. Result: smaller signal than expected
Sunyaev-Zel’dovich Effect
Parametric Use a template for the signal and fit for the free amplitude (matched filter). Signal smaller than predicted … in agreement with Planck
Cluster-CMB Lensing
Initial papers (Zaldarriaga 1999) pointed to distinctive signal: lensing a dipole. Hot side is slightly cooler since photons arrive from farther away; cool side is slightly hotter. Remove the dipole dimples
Likelihood Approach
Amplitudes of lensing and SZ signal
Data in pixel iSZ Template in pixel i
with covariance matrix that depends on the deflection angle
Works well when using correct templates
SPT parameters (beam, noise, sky coverage, cluster count)
Works less well when applied to independently generated mocks with
different lensing templates and scatter
Conclusion
• Inflation: Look for upcoming results on physics of inflation (B-modes, Non-Gaussianity, n’)
• Neutrinos: Tantalizing results for Neff and capable of discovering inverted hierarchy
• Dark Energy: – Evidence from CMB only– Will help propel clusters to viable DE probe
Knox & Song; Kesden, Cooray, & Kamionkowski 2002
Clean up B-mode contamination and measure even small tensor component
Probe inflation even if energy scale is low
What can we do with this?
Non-Gaussianity: Large Scale Bias
Local Non-Gaussianity corresponds to:
)()()( 2 xfxx GNLG
Dalal et al. (2008) showed that this leaves a characteristic imprint on large scale structure
Non-Gaussianity: Large Scale BiasNon-Gaussianity: Large Scale Bias
Consider the density field in 1D. A given region is collapsed (i.e. forms a halo) if the density is larger than a critical value.
Critical density
Long Wavelength mode
Non-Gaussianity: Large Scale BiasNon-Gaussianity: Large Scale Bias
Add in short wavelength modes. For this one realization, the second peak has collapsed into a halo.
Non-Gaussianity: Large Scale BiasNon-Gaussianity: Large Scale Bias
More generally, short wavelength modes drawn from a distribution with given rms (red curves)
Halos more likely to form in region of large scale overdensity = bias
Non-Gaussianity: Large Scale BiasNon-Gaussianity: Large Scale Bias
Change with primordial NG: more small-scale fluctuations in region of large scale over-density more bias on large scale
Non-Gaussianity: Large Scale Bias
Slosar et al. (2009)
100NLf
Non-Gaussianity ElsewhereNon-Gaussianity Elsewhere
Reionization proceeds more rapidly in NG models (Adshead, Baxter, Dodelson, Lidz 2012)
Non-Gaussianity ElsewhereNon-Gaussianity Elsewhere
May learn about inflation from surveys from infrared or 21 cm observations