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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?.

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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
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
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
If they do all start out with the same phase …

First peak will be well-defined


Time/(400,000 yrs)

as will first trough
As will first trough ...

And all subsequent peaks and troughs


Time/(400,000 yrs)

if all modes are not synchronized though
If all modes are not synchronized though

First “Trough”

First “Peak”



Time/(400,000 yrs)

Time/(400,000 yrs)

We will NOT get series of peaks and troughs!

evidence for new physics
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
What’s Next?
  • Physics Driving Inflation
  • Neutrino Masses and Abundances
  • Nature of Dark Energy
non gaussianity

Current observations



Smith, Senatore, & Zaldarriaga (2009)Slosar et al. (2008)

Upcoming observations



If local NG is found in the next decade, single field models of inflation will be falsified

gravitational waves elsewhere
Gravitational Waves Elsewhere

Primordial Gravitational Waves also produce lensing B-modes. B-mode lensing (call it ω) spectrum peaks on the largest scales*

Noise Estimate

Scalar leakage

GW wave signal

Dodelson, Rozo, & Stebbins (2003)

Sarkar et al. (2008)

Dodelson (2010)

Masui & Pen (2010)

Book, Kamionkowski, & Schmidt (2011)

*Might be good way to test for bubble collisions predicted by eternal inflation

gravitational waves elsewhere1
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
Cross-Correlation is non-negligible

Depends on l and redshift of source galaxies; might devise weighting scheme to optimize signal. Detection would eliminate systematics.

effect of adding extra neutrinos hou et al 2011
Effect of adding extra neutrinos (Hou et al. 2011)
  • H-1goes 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
current constraints
Current Constraints

SPT favors high Neff (as do other small scale CMB expeirments)

preliminary spt spectrum
Preliminary SPT Spectrum

Look for tighter neutrino constraints and constraints on n’

secondary anisotropies
Secondary Anisotropies

kSZ: Reionization

Thermal SZ: Clusters, LSS

Cosmic Shear

Cluster Lensing

Scattering off electrons

Gravitational Lensing

lensing of the cmb
Lensing of the CMB

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

Hu 2002

lensing of the cmb1
Lensing of the CMB

Primordial unlensedtemperature Tuis re-mapped to

where the deflection angle is a weighted integral of the gravitational potential along the line of sight

lensing of the cmb2
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

lensing of the cmb3
Lensing of the CMB

ACT, a high resolution experiment, has detected lensing of the CMB and estimated the power spectrum of the lensing structures

Atacama Cosmology Telescope

Das et al. 2011

Matter-only model predicts more structure

lensing of the cmb4
Lensing of the CMB

Lensing amplitude + primary acoustic peak structure provide evidence for acceleration from the CMB alone at 3.2 sigma

Sherwin et al. 2011


Van Engelen et al 1202.0546

South Pole Telescope has detcted this at > 6-sigma


Difference between massless spectrum and one with 0.1 eV

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!

Hall & Challinor 2012

clusters and dark energy
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
Sunyaev-Zel’dovich Effect

12.6 M pixels of 3.4’ size

13,823 Clusters in SDSS

Challenge: Large WMAP pixels

sunyaev zel dovich effect1
Sunyaev-Zel’dovich Effect


Average T in annuli around massive (blue) and less massive (red) clusters. Compare to predictions accounting for CMB noise. Result: smaller signal than expected

Draper, Dodelson, Hao, & Rozo (2012)

sunyaev zel dovich effect2
Sunyaev-Zel’dovich Effect


Use a template for the signal and fit for the free amplitude (matched filter). Signal smaller than predicted … in agreement with Planck

Draper, Dodelson, Hao, & Rozo (2012)

cluster cmb lensing
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
Likelihood Approach

Amplitudes of lensing and SZ signal

Data in pixel i

SZ Template in pixel i

with covariance matrix that depends on the deflection angle

works well when using correct templates
Works well when using correct templates

SPT parameters (beam, noise, sky coverage, cluster count)

Baxter & Dodelson (2012)

Works less well when applied to independently generated mocks with different lensing templates and scatter

Baxter & Dodelson (2012)

  • 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

What can we do with this?

Clean up B-mode contamination and measure even small tensor component

Probe inflation even if energy scale is low

Knox & Song; Kesden, Cooray, & Kamionkowski 2002

non gaussianity large scale bias
Non-Gaussianity: Large Scale Bias

Local Non-Gaussianity corresponds to:

Dalal et al. (2008) showed that this leaves a characteristic imprint on large scale structure


Non-Gaussianity: Large Scale Bias

Critical density

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.

Long Wavelength mode


Non-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 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 Bias

Change with primordial NG: more small-scale fluctuations in region of large scale over-density  more bias on large scale


Non-Gaussianity Elsewhere

Reionization proceeds more rapidly in NG models (Adshead, Baxter, Dodelson, Lidz 2012)


Non-Gaussianity Elsewhere

May learn about inflation from surveys from infrared or 21 cm observations