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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 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 Our Motion Key Concepts At the level of 1 part in 1000 the CMB temperature varies because of our motion with respect to it If we turn up the contrast on the previous map to see fluctuations at the level of one part in 1000 the COBE sky map looks like this Aside from some deviations about the equator this pattern is a pure dipole A dipole has its maxima and minima red and

    Original URL path: http://background.uchicago.edu/~whu/intermediate/map3.html (2015-06-26)
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  • CMB Introduction
    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 Large Scale Anisotropy Key Concepts COBE showed that the CMB temperature varied at a level of 1 part in 100 000 Variations are consistent with begin the quantum noise from inflation that formed structure through gravitational instability If we remove the dipole and turn up the contrast on the previous map to the level of one part in 100 000 the COBE maps reveal Again ignore the pattern around the equator as that is our own galaxy If you ve never seen this map before I m sure your natural reaction is Um well it looks like noise to me Well actually that is exactly what it is But not in the bad sense We believe that

    Original URL path: http://background.uchicago.edu/~whu/intermediate/map4.html (2015-06-26)
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  • CMB Introduction
    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 Power Spectrum Key Concepts The power spectrum characterizes the size of the fluctuations as a function of angular scale COBE meaured only the largest angular scales in the power spectrum At smaller angular scales features are expected in the power spectrum Ok so if what we are dealing with is actually noise in the technical sense what do we do with it When dealing with noise what we want to do is determine its spectral properties is the noise white red or blue Does it have any features In this case when we speak of the spectrum of the noise we are talking about the angular coherence of the temperature fluctuations rather than the temporal coherence of audible noise Instead of temporal frequency we speak of angular frequency called the multipole moment l The reciprocal of l corresponds to the angular scale which we will call the angular wavelength of the fluctuation For example l 10 corresponds to roughly 10 degrees on the sky l 100 corresponds to roughly 1 degree on the sky Mathematically the multipole moments arise from a spherical harmonic decomposition of the fluctuations in angle With its resolution of 7 degrees on the sky the COBE satellite could only see the largest angle fluctuations The units on the y axis are in micro millionth of a Kelvin Since the temperature of the CMB is measured to be 2 73K this makes the fluctuations 1 part in 100 000 as advertised Mathematically the power spectrum is actually

    Original URL path: http://background.uchicago.edu/~whu/intermediate/map5.html (2015-06-26)
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  • CMB Introduction
    Material 96 nbsp PhD Thesis 95 Baryon Acoustic Oscillations Cosmic Shear 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 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 Scaling the Acoustic Peaks Key Concepts Current generation of experiments measure the fine scale structure of the CMB temperature maps Explosion of new data in recent years have ushered in the age of precision cosmology Naturally then the goal of CMB experiments after COBE has been to increase the angular resolution of the maps and study the small scale features in the

    Original URL path: http://background.uchicago.edu/~whu/intermediate/map6.html (2015-06-26)
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  • CMB Introduction
    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

    Original URL path: http://background.uchicago.edu/~whu/intermediate/map7.html (2015-06-26)
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  • CMB Introduction
    Cosmic Shear 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

    Original URL path: http://background.uchicago.edu/~whu/intermediate/thermal.html (2015-06-26)
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  • CMB Introduction
    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 Expansion of the Universe Key Concepts Objects seem to receed as the universe expands Wavelength of CMB photons stretches with the expansion Temperature of the CMB drops with the expansion As the universe expands everything that isn t bound by electromagnetic or other interactions expands with it This includes the distance between galaxies and the wavelength of CMB photons The expansion of the universe was first inferred when Hubble discovered that distant galaxies appear to be receding from us Imagine that you are the observer sitting at the pole of an expanding Earth Distant objects appear to be receding at a rate proportional to their distance You can convince yourself that there is nothing special about the pole Despite the fact that we see

    Original URL path: http://background.uchicago.edu/~whu/intermediate/expansion.html (2015-06-26)
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  • CMB Introduction
    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 Recombination Key Concepts Photons get hotter as one goes backwards in time At 3000K CMB photons ionize hydrogen Above this temperature the universe was a photon baryon proton plasma Going backwards in time the expansion reverses The redshifting of photons by the stretching of space becomes a blueshift ing When the universe was one thousandths of its current size the CMB was a thousand times hotter and had a temperature of 3000K At this point photons in the tails of the distribution had enough energy to break the hydrogen atom into a proton and an electron Note This process is called recombination since going

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