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Precision Cosmology and Primordial Perturbations in the Early Universe

Explore the evolution of the universe from opaque to transparent states, focusing on constraints, predictions, and analysis of primordial perturbations in the Cosmic Microwave Background for accurate parameter estimation and cosmological implications.

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Precision Cosmology and Primordial Perturbations in the Early Universe

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  1. Primordial perturbations and precision cosmology from the Cosmic Microwave Background Antony Lewis CITA, University of Toronto http://cosmologist.info

  2. Evolution of the universe Opaque Transparent Hu & White, Sci. Am., 290 44 (2004)

  3. Perturbation evolutionEarly universe to last scattering

  4. Contributions to cosmology • Constraints on primordial perturbations • Observable primordial isocurvature and vector modes (identification and predictions) • CMB polarization analysis: solution to E/B mode separation problem • Simulation and parameter estimation with CMB lensing • Ab initio quantum gravity calculation of primordial perturbations and CMB in closed instanton model • Fastest and most accurate code for calculating CMB anisotropy power spectra from initial conditions + parameters (CAMB) • Methods for fast Monte Carlo parameter estimation from cosmological data (CosmoMC code) • Accurate parameter constraints from CMB + other data (e.g. galaxy lensing) • Evolution of dark matter and dark energy perturbations: efficient methods, numerical predictions, parameter constraints • CMB signatures of primordial magnetic fields

  5. CMB temperature power spectrumPrimordial perturbations + later physics Redhead et al: astro-ph/0402359

  6. Primordial Perturbationsfluid at redshift < 109 • Photons • Neutrinos • Baryons + electrons • Cold Dark Matter • Dark energyprobably negligible early on

  7. General regular linear primordial perturbation -isocurvature- + irregular modes, neutrino n-pole modes, n-Tensor modes Rebhan and Schwarz: gr-qc/9403032+ other possible components, e.g. defects, magnetic fields, exotic stuff…

  8. Adiabatic modesWhat is the primordial power spectrum? Bridle, Lewis, Weller, Efstathiou: astro-ph/0302306 Isocurvature modesCurvaton model? Gordon, Lewis:astro-ph/0212248

  9. Primordial Gravitational Waves(tensor modes) • Well motivated by some inflationary models- Amplitude measures inflaton potential at horizon crossing- distinguish models of inflation • Observation would rule out other models- ekpyrotic scenario predicts exponentially small amplitude - small also in many models of inflation, esp. two field e.g. curvaton • Weakly constrained from CMB temperature anisotropy Look at CMB polarization

  10. E and B polarization • E polarization from scalar, vector and tensor modes • B polarization only from vector and tensor modes B is ‘smoking gun’ for primordial vector and tensor modes

  11. Vector and Tensor B mode spectrum Non-linear scalar modes also give small B signal B-modes Lewis: astro-ph/0403583

  12. Polarization complications • E/B mixing • Lensing of the CMB

  13. E/B mixing and solution Underlying B-modes Part-sky mix with scalar E Observation Separation method Recovered B modes‘map of gravity waves’ Lewis: astro-ph/0305545

  14. Weak lensing of the CMB Last scattering surface Inhomogeneous universe - photons deflected Observer • Lensing B-modes • Changed power spectra Lewis: PRD submitted; Challinor, Lewis: in preparation

  15. Future work • Cosmological parameters from forthcoming CMB data (Planck, Clover, etc.) + galaxy lensing etc. • Reconstruction of initial power spectrum and constraints on inflation and other models • Improved treatment of CMB lensing: lensing reconstruction, B-mode cleaning, un-lensing the temperature • Statistical methods: Monte Carlo methods for CMB map-making, polarization analysis and weak lensing • Cosmology from 21cm and galaxy weak lensing (+CMB) • Tests of new physics, string theory, etc; early universe models • New things…

  16. Parameter estimation: sampling from P(parameters|data) CMB data alonecolor = optical depth Samples in6D parameterspace

  17. Plot number density of samples as function of parameters e.g. CMB+galaxy lensing +BBN prior CosmoMC code athttp://cosmologist.info/cosmomcLewis, Bridle:astro-ph/0205436 Contaldi, Hoekstra, Lewis: astro-ph/0302435

  18. Conclusions • CMB contains lots of useful information!- primordial perturbations + well understood physics (cosmological parameters) • Precision cosmology- sampling methods used to constrain many parameters with full posterior distribution • Currently no evidence for any deviations from standard near scale-invariant purely adiabatic primordial spectrum • B-mode polarization - primordial gravitational waves + vector modes: - energy scale of inflation - rule out most ekpyrotic and pure curvaton/ inhomogeneous reheating models and others • Weak lensing of CMB :- B-modes potentially confuse primordial signals- Have to account for effect on power spectra • Foregrounds, systematics, etc, may make things much more complicated!

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