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  • CMB Introduction
    University of Chicago Astronomy Department KICP Thunch astro ph CO ADS InSpire Introduction Temperature Maps Earth Monopole Dipole COBE Power Precision Features Thermal History Expansion Plasma Glue Pressure Thermal Acoustic Oscillations Gravity Plane Waves Harmonics Extrema Angular Peaks Spatial Angular Oscillation Freeze Frame Streaming Soundscape First Peak Data Curvature Flatness Dark Energy Summary Second Peak Data Inertia Baryonmeter Power Dark Baryons Summary Higher Peaks Driving Force Power Summary Damping Tail Diffusion Ruler Consistency Summary Parameter Estimation Parameters Degeneracy Polarization What and Why Scattering Projection Power Quadrupoles B modes Gravity Waves Summary A Flat Universe Key Concepts First peak position consistent with flat universe Precision currently limited by uncertainties in the Hubble constant through the physical density of the dark matter Main ambiguity will be removed by measuring higher peaks Now let s have a look at the data again The position of the first peak indicates that the universe is very close to spatially flat In terms of a parameterization where the dark matter density and dark energy or cosmological constant dominates the energy density of the universe today a flat universe has Omega m Omega Lambda 1 and lies on the red line We will see why we introduce the dark energy in the next section How close to perfectly flat is the universe The answer to that question is an currently an evasive that depends In fact reasonable people say different things and report constraints in the above plane that mean different things Here we display the literal 95 confidence constraints described by the Boomerang and Maxima groups in their respective detection papers The observations themselves are exquisitely precise and the ambiguity does not lie there The problem is that thing we shoved under the rug in the description of the test for curvature There is currently a

    Original URL path: http://background.uchicago.edu/~whu/intermediate/flatness.html (2015-06-26)
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  • CMB Introduction
    CO ADS InSpire Introduction Temperature Maps Earth Monopole Dipole COBE Power Precision Features Thermal History Expansion Plasma Glue Pressure Thermal Acoustic Oscillations Gravity Plane Waves Harmonics Extrema Angular Peaks Spatial Angular Oscillation Freeze Frame Streaming Soundscape First Peak Data Curvature Flatness Dark Energy Summary Second Peak Data Inertia Baryonmeter Power Dark Baryons Summary Higher Peaks Driving Force Power Summary Damping Tail Diffusion Ruler Consistency Summary Parameter Estimation Parameters Degeneracy Polarization What and Why Scattering Projection Power Quadrupoles B modes Gravity Waves Summary Dark Energy Key Concepts CMB indicates the total energy density is close to critical flat universe Many observations indicate that the dark matter energy density is sub critical Dark energy is required to make these statements consistent Amount of dark energy is consistent with that needed to explain distant supernovae Why introduce the mysterious dark energy into the game Why not just say that the flatness of the universe implies that the dark matter density is close to critical There is a considerable amount of evidence that the density of dark matter is very much less than critical The strongest lines of evidence come from clusters of galaxies Tests like those found in measurements of the abundance and baryon fractions of galaxy clusters only probe energy components that can cluster with galaxies If we want to have a low density of dark matter and still have a flat universe one has to postulate a new component of energy that is spatially smooth and cannot cluster with galaxies The simplest example of such a component is Einstein s cosmological constant a remarkable type of energy density that is constant in both space and time The inference of dark energy taking up some 60 80 of the total energy density is nicely consistent with measurements of the luminosity distance to

    Original URL path: http://background.uchicago.edu/~whu/intermediate/darkenergy.html (2015-06-26)
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  • CMB Introduction
    Transfer Function WMAP Likelihood Reionization PPF for CAMB Halo Mass Conversion Cluster Abundance Cosmology 321 Current Topics 282 Galaxies and Universe 242 Radiative Processes 305 Research Preparation 307 GR Perturbation Theory 408 Advanced CMB 448 University of Chicago Astronomy Department KICP Thunch astro ph CO ADS InSpire Introduction Temperature Maps Earth Monopole Dipole COBE Power Precision Features Thermal History Expansion Plasma Glue Pressure Thermal Acoustic Oscillations Gravity Plane Waves Harmonics

    Original URL path: http://background.uchicago.edu/~whu/intermediate/score1a.html (2015-06-26)
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  • CMB Introduction
    Clusters Transfer Function WMAP Likelihood Reionization PPF for CAMB Halo Mass Conversion Cluster Abundance Cosmology 321 Current Topics 282 Galaxies and Universe 242 Radiative Processes 305 Research Preparation 307 GR Perturbation Theory 408 Advanced CMB 448 University of Chicago Astronomy Department KICP Thunch astro ph CO ADS InSpire Introduction Temperature Maps Earth Monopole Dipole COBE Power Precision Features Thermal History Expansion Plasma Glue Pressure Thermal Acoustic Oscillations Gravity Plane Waves

    Original URL path: http://background.uchicago.edu/~whu/intermediate/second.html (2015-06-26)
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  • CMB Introduction
    Likelihood Reionization PPF for CAMB Halo Mass Conversion Cluster Abundance Cosmology 321 Current Topics 282 Galaxies and Universe 242 Radiative Processes 305 Research Preparation 307 GR Perturbation Theory 408 Advanced CMB 448 University of Chicago Astronomy Department KICP Thunch astro ph CO ADS InSpire Introduction Temperature Maps Earth Monopole Dipole COBE Power Precision Features Thermal History Expansion Plasma Glue Pressure Thermal Acoustic Oscillations Gravity Plane Waves Harmonics Extrema Angular Peaks Spatial Angular Oscillation Freeze Frame Streaming Soundscape First Peak Data Curvature Flatness Dark Energy Summary Second Peak Data Inertia Baryonmeter Power Dark Baryons Summary Higher Peaks Driving Force Power Summary Damping Tail Diffusion Ruler Consistency Summary Parameter Estimation Parameters Degeneracy Polarization What and Why Scattering Projection Power Quadrupoles B modes Gravity Waves Summary Second Peak Key Concepts Second peak is essentially incontrovertable evidence of inflationary sound waves As of May 2001 the first detections of the second peak have been reported by the DASI Boomerang and Maxima experiments The predication of a second peak at a position that is a harmonic of the first peak is an immediate and unavoidable consequence of the interpretation of the first peak as being due to sound waves from gravitational potential perturbations layed down

    Original URL path: http://background.uchicago.edu/~whu/intermediate/secgen.html (2015-06-26)
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  • CMB Introduction
    307 GR Perturbation Theory 408 Advanced CMB 448 University of Chicago Astronomy Department KICP Thunch astro ph CO ADS InSpire Introduction Temperature Maps Earth Monopole Dipole COBE Power Precision Features Thermal History Expansion Plasma Glue Pressure Thermal Acoustic Oscillations Gravity Plane Waves Harmonics Extrema Angular Peaks Spatial Angular Oscillation Freeze Frame Streaming Soundscape First Peak Data Curvature Flatness Dark Energy Summary Second Peak Data Inertia Baryonmeter Power Dark Baryons Summary Higher Peaks Driving Force Power Summary Damping Tail Diffusion Ruler Consistency Summary Parameter Estimation Parameters Degeneracy Polarization What and Why Scattering Projection Power Quadrupoles B modes Gravity Waves Summary Baryons and Inertia Key Concepts Baryons load down the photon baryon oscillations Compression i n potential wells enhanced over rarefactions Baryons or ordinary matter load down the photon baryon plasma and add inertial and gravitational mass to the oscillating system Their effect on the acoustic peaks is easy to understand Remember what happens when you add mass to a spring and let it fall in the gravitational field of the Earth With more mass loading the spring it falls further before pulled back by the spring On the other hand it rebounds to the same position it started from Since the

    Original URL path: http://background.uchicago.edu/~whu/intermediate/baryons.html (2015-06-26)
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  • CMB Introduction
    Current Topics 282 Galaxies and Universe 242 Radiative Processes 305 Research Preparation 307 GR Perturbation Theory 408 Advanced CMB 448 University of Chicago Astronomy Department KICP Thunch astro ph CO ADS InSpire Introduction Temperature Maps Earth Monopole Dipole COBE Power Precision Features Thermal History Expansion Plasma Glue Pressure Thermal Acoustic Oscillations Gravity Plane Waves Harmonics Extrema Angular Peaks Spatial Angular Oscillation Freeze Frame Streaming Soundscape First Peak Data Curvature Flatness Dark Energy Summary Second Peak Data Inertia Baryonmeter Power Dark Baryons Summary Higher Peaks Driving Force Power Summary Damping Tail Diffusion Ruler Consistency Summary Parameter Estimation Parameters Degeneracy Polarization What and Why Scattering Projection Power Quadrupoles B modes Gravity Waves Summary Baryonmeter Key Concepts Asymmetric oscillations due to baryons enhance compressional phase inside wells Amplitude of odd peaks enhanced over even peaks Now let s add the potential wells back into the picture The picture is only slightly more complicated If the baryons contribute a negligible amount of mass to the plasma the CMB temperature at the bottom of the potential well oscillates symmetrically around zero The temporal behavior of the temperature is illustrated on the right With more baryons in the system the plasma is loaded down The plasma

    Original URL path: http://background.uchicago.edu/~whu/intermediate/baryons2.html (2015-06-26)
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  • CMB Introduction
    Temperature Maps Earth Monopole Dipole COBE Power Precision Features Thermal History Expansion Plasma Glue Pressure Thermal Acoustic Oscillations Gravity Plane Waves Harmonics Extrema Angular Peaks Spatial Angular Oscillation Freeze Frame Streaming Soundscape First Peak Data Curvature Flatness Dark Energy Summary Second Peak Data Inertia Baryonmeter Power Dark Baryons Summary Higher Peaks Driving Force Power Summary Damping Tail Diffusion Ruler Consistency Summary Parameter Estimation Parameters Degeneracy Polarization What and Why Scattering Projection Power Quadrupoles B modes Gravity Waves Summary Baryons in the Power Spectrum Key Concepts Power spectrum shows baryons enhance every other peak Second peak is suppressed compared with the first and third Additional effects on the peak position and damping yield consistency checks When we do the full calculation of the power spectrum the basic physics of a mass on the spring appears as advertised The odd numbered acoustic peaks in the power spectrum are enhanced in amplitude over the even numbered ones as we increase the baryon density of the universe Note Cosmologists label the baryon density in terms of its fraction of the critical density W b times the Hubble constant squared in units of 100 km s Mpc to get something proportional to the physical density

    Original URL path: http://background.uchicago.edu/~whu/intermediate/baryons3.html (2015-06-26)
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