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**Planck 2013 results, implications for cosmology**

Michele Liguori Department of Physics and Astronomy, University of Padova On behalf of the Planck collaboration

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CMB basics In big bang cosmology the Universe is initially in a hot and dense state Free electrons and nuclei interact with photons via Compton scattering As the Universe cools down, electrons combine with photons to form Hydrogen atoms (recombination) matter-radiation decoupling Time of decoupling ~ yrs. Temperature at decoupling ~ 3000 K. Due to Universe expansion the CMB has today a blackbody spectrum with color temperature T ~ 2.7 K The Early Universe is nearly, but not perfectly homogeneous and isotropic. Matter and radiation accrete onto overdense regions anisotropies in the CMB spatial temperature distribution M. Liguori ”Planck 2013 results, implications for cosmology"

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**Initial conditions Inhomogeneous Homogeneous INFLATION x 100,000**

M. Liguori ”Planck 2013 results, implications for cosmology"

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**Generation of temperature anisotropies**

On large scales: density fluctuations at last scattering + gravitational redshift (SW effect) On intermediate scales: acoustic oscillations On small scales: Damping due to photon free streaming (Silk damping) M. Liguori ”Planck 2013 results, implications for cosmology"

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**The CMB as seen by Planck**

M. Liguori ”Planck 2013 results, implications for cosmology"

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The power spectrum M. Liguori ”Planck 2013 results, implications for cosmology"

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**Sensitivity instrumental noise beam signal sky coverage**

Even for an ideal noiseless experiment error bars are not 0 due to cosmic variance An experiment is: Cosmic variance dominated where the error budget is dominated by the cosmic variance term (instrumental noise is negligible, low l) Signal dominated where Cl > Nl (low l) Noise dominated when Nl > Cl (high l) M. Liguori ”Planck 2013 results, implications for cosmology"

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Planck, main features Large frequency coverage: 30, 44, 70, 100, 143, 217, 353, 545, 857 Ghz . Allows accurate separation of galactic and extragalactic foregrounds Two different instruments: LFI radiometers in the [30 Ghz; 70 Ghz] range, HFI bolometers in the [100 Ghz; 857 Ghz] range. Allows tight control of systematics Full sky coverage High sensitivity: signal dominated for l<2000, cosmic variance dominated for l<1500 High angular resolution: between 14 and 5 arcmin for cosmologically most relevant channels M. Liguori ”Planck 2013 results, implications for cosmology"

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**M. Liguori ”Planck 2013 results, implications for cosmology"**

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**COBE, WMAP, Planck Npix ~ 104 FWHM ~ 7o lmax ~ 30 Npix ~ 3×106**

FWHM ~ 12 arcmin lmax ~ 1000 Npix ~ 5×107 FWHM ~ 5 arcmin lmax ~ 3000 Planck M. Liguori ”Planck 2013 results, implications for cosmology"

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**Frequency maps “cleaning + coadding”**

M. Liguori ”Planck 2013 results, implications for cosmology"

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**Planck CMB power spectrum**

M. Liguori ”Planck 2013 results, implications for cosmology"

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WMAP+Planck+ACT+SPT M. Liguori ”Planck 2013 results, implications for cosmology"

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**Cosmological parameters**

A 6-parameters LCDM model allows a very good fit of the data: Baryon density: Wb Matter density: Wm Acoustic scale (angular size): qMC Optical depth to reionization: t Amplitude of primordial scalar fluctuations: As Scalar Spectral index: ns M. Liguori ”Planck 2013 results, implications for cosmology"

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**Effect of changing parameters on Cl**

M. Liguori ”Planck 2013 results, implications for cosmology"

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**Planck parameters measurements**

M. Liguori ”Planck 2013 results, implications for cosmology"

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**Extensions to the “minimal” model**

M. Liguori ”Planck 2013 results, implications for cosmology"

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More extensions… M. Liguori ”Planck 2013 results, implications for cosmology"

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CMB lensing Large scale structure deflects the trajectory of CMB photons through gravitational lensing Deflection angle CMB lensing potential Can build quadratic estimators of the lensing potential, exploiting the breaking of isotropy i.e. the appearance of off-diagonal term in the alm covariance matrix (equivalently, the coupling between T and grad T ) The lensing potential depends on cosmological parameters and probes completely different redshifts w.r.t primary anisotropies! Lensing also affects the Cl directly (“redistribution of scales” and damping) M. Liguori ”Planck 2013 results, implications for cosmology"

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**Planck lensing measurements**

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**Neutrino masses Cosmological measurements constrain**

Massive neutrinos below free streaming scale do not cluster, thus the gravitational potential decays at small scales during matter domination in this case Main effect on CMB: changes in lensing (less smoothing of peaks, less power in lensing likelihood at L > 10) Without lensing the constraining power of CMB alone is small. Previous measurements used generally a combination of CMB and LSS data Planck +WMAP low-l M. Liguori ”Planck 2013 results, implications for cosmology"

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**The bispectrum l3 l2 l1 lmax lmax**

M. Liguori ”Planck 2013 results, implications for cosmology"

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**Bispectrum definition**

l3 l2 l2 l3 l1 l1 M. Liguori ”Planck 2013 results, implications for cosmology"

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**Bispectrum definition**

l3 squeezed l2 l1 M. Liguori ”Planck 2013 results, implications for cosmology"

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**Bispectrum definition**

l3 squeezed equilateral l2 l1 M. Liguori ”Planck 2013 results, implications for cosmology"

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**Bispectrum definition**

l3 squeezed equilateral l2 flat flat l1 M. Liguori ”Planck 2013 results, implications for cosmology"

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**Shapes Local Equilateral Orthog. ISW-l.**

M. Liguori ”Planck 2013 results, implications for cosmology"

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**fNL from Planck data SMICA SEVEM NILC C-R**

M. Liguori ”Planck 2013 results, implications for cosmology"

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**The Planck bispectrum NILC SEVEM SMICA SMICA WAVES SMICA POLYS**

M. Liguori ”Planck 2013 results, implications for cosmology"

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**M. Liguori ”Planck 2013 results, implications for cosmology”**

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Conclusions Planck is a full-sky CMB satellite characterized by unprecedented sensitivity and frequency coverage We summarized some of the main cosmological results of the first Planck data release, including: High precision measurements of cosmological parameters, in very good agreement with the standard 6-parameters LCDM model 25s detection of CMB lensing and lensing potential reconstruction Constraints on neutrino masses High precision constraints on primordial non-Gaussianity and bispectrum reconstruction The future: Twice as many data in the full mission compared to the nominal mission Polarization!! M. Liguori ”Planck 2013 results, implications for cosmology"

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