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  • Weak
    scenarios and the Vishniac effect The Vishniac effect can dominate primary anisotropies at small angles even in late and minimally reionized models in flat dark matter dominated universes with Harrison Zel dovich initial conditions The techniques developed here refine previous calculations yielding a larger coherence angle for the Vishniac effect and moreover can be applied to non trivial ionization histories These analytic expressions may be used to modify results for

    Original URL path: http://background.uchicago.edu/~whu/weak/weakpage.html (2015-06-26)
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  • Photos
    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 Travelog 1 2 3 4 5 6 7 8 9 10 11 12 prev next past sojourns Loading Please wait Vide Supra Yokohama Japan 2014 Temple of Ra Shin Yokohama Japan 2014 Doomed Yet Set pt 2 Kamakura Japan 2014 Noble Kawagoe Japan 2014 12 14 is 47 Sengakuji Japan 2014 Gleaming Meaning Tokyo Japan 2014 Signs of Quenching Seoul Korea 2014 Hints of Awakening Songnisan Korea 2014 That which Remains Beopjusa Korea 2014 Overview Slide Daejeon Korea 2014 Coffee Breakaway Dope Bicep Pasadena CA 2014 Fingers of God Sedona AZ 2013 Fat Man and Little Boy Scottsdale AZ 2013 Caved In Healdsburg CA 2013 Shrouded In Sonoma Coast 2013 Burn Portsmouth 2013 Blind Watchers Stonehenge 2013 Behind the Curve Salisbury 2013 Contemplating the Fall Woolsthorpe 2013 Foxed Out Nottingham 2013 In Plumian Spires London 2013 End of the Tunnel Drain Doi Poi 2012 End of the Tunnel Light Chiang Mai 2012 Out There It s a Hua Hin 2012 Two Towers Little Men Bangkok 2012 End of Days Numbered Irrationally Tokyo 2012 End of

    Original URL path: http://background.uchicago.edu/~whu/travelog (2015-06-26)
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  • CMB Introduction
    InSpire Introduction Basic Principles Expansion Cosmic Light History Inflation Mapping Anisotropy Sound Waves Music Curvature Summary Basic Principles Key Concepts Big Bang the universe began hot and dense and thereafter expanded and cooled Gravitational Instability Stars galaxies clusteres of galaxies structure formed from the gravitational pull of small density ripples in the early universe As cosmologists the main paradigms we work under are known rather inapproprately as the big bang

    Original URL path: http://background.uchicago.edu/~whu/beginners/basic.html (2015-06-26)
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  • CMB Introduction
    Background we are bathed in primordial light The big bang or hot expanding model of cosmology finds strong support from the recession of the galaxies that is when we look out in the night sky distant objects appear to be flying away from us And also the cosmic microwave background the fact that we are bathed in primordial light that bears evidence from and earlier hotter and denser period in the universe As we shall see this evidence also supports the gravitational instability paradigm the picture that gravity can make wrinkles into galaxies The relation between recession and expansion is easy to understand Imagine you re standing at the north pole and think boy I d much rather be at the basking the sun at some equatorial paradise You look up the distance to it and plan your trip Right before you leave you think I d better check the distance again Unbeknownst to you the radius of the earth has expanded in the meantime To your suprise the distance to your equatorial paradise is now larger You think that s funny paradise seems to be receding from me This is exactly the situation we observe with the distant galaxies

    Original URL path: http://background.uchicago.edu/~whu/beginners/expansion.html (2015-06-26)
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  • CMB Introduction
    Light History Inflation Mapping Anisotropy Sound Waves Music Curvature Summary Properties of Cosmic Light Key Concepts Cosmic microwave background CMB primordial light 3 degrees above absolute zero 270 degrees celcius mm cm wavelength 400 photons per cubic centimeter 10 trillion photons per second per squared centimeter Few percent of TV snow Temperature slightly different on different patches of the sky 1 part in 100 000 Because of the expansion the microwave background is very cold now 3 degrees above absolute zero It s wavelength has been stretched out of the visible and into the microwave regime of millimeters to centimeters This is the same type of radiation that heats your food but a few percent of its wavelength and of course not especially tuned to cook things In terms of photons or packets of light there are quite a few of them in the microwave background about 400 per cubic centimeter Since they travel at the speed of light that means quite a large number of them are whizzing through each patch of space each second Unfortunately just as your eyes aren t tuned to see radio or TV waves they aren t tuned to see microwaves TV waves at

    Original URL path: http://background.uchicago.edu/~whu/beginners/properties.html (2015-06-26)
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  • CMB Introduction
    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 Basic Principles Expansion Cosmic Light History Inflation Mapping Anisotropy Sound Waves Music Curvature Summary Brief History Key Concepts Looking at distant objects we look backwards in time Galaxies formed when the universe was a few billion years old Microwave background radiation was emitted when the universe was about 300 000 years old Before 300 000 years the universe was a nearly smooth particle soup When we look out in the sky we re actually looking backwards in time Light from more distant objects take longer to reach us and thus we are observing now how they appeared in the past We can see back a few billion years with the light of galaxies The microwave light of the background shines from long ago in an infant universe 300 000 years old the epoch of last scattering and illuminates the particle soup that existed before this time This soup

    Original URL path: http://background.uchicago.edu/~whu/beginners/brief.html (2015-06-26)
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  • CMB Introduction
    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 Basic Principles Expansion Cosmic Light History Inflation Mapping Anisotropy Sound Waves Music Curvature Summary Cosmic Inflation Key Concepts Inflation stretches fluctuations at the elementary particle into galaxy large wrinkles Cosmological horizon the distance beyond which we cannot look An important concept in structure formation One question that remains unanswered is what is the origin of such large scale wrinkles in the first place One theory is that a period of rapid expansion takes very small scale fluctuations at the level of the particle soup and stretches them to cosmic proportions Here the blue bands are snapshots of the wrinkles in the density of the universe at various times As time goes on matter falls into these wrinkles and starts to build heavier and heavier objects The crucial period when this process of gravitational attraction and infall can occur is related to an important concept in cosmology called the horizon Like the horizon on the earth it is the point beyond which we re unable to look Unlike the earth

    Original URL path: http://background.uchicago.edu/~whu/beginners/infl.html (2015-06-26)
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  • CMB Introduction
    408 Advanced CMB 448 University of Chicago Astronomy Department KICP Thunch astro ph CO ADS InSpire Introduction Basic Principles Expansion Cosmic Light History Inflation Mapping Anisotropy Sound Waves Music Curvature Summary Temperature Sky Maps Key Concepts Temperature anisotropies small variations in the temperature of the microwave background radiation from one direction on the sky to the other Temperature map representation of the 3 dimensional sky in a 2 dimensional plane Small variations in the temperature of the background radiation from point to point on the sky are called anisotropies These anisotropies were first detected by the COBE satellite in 1992 They produced a map of the sky where the colors represent temperature on the sky To get a better feel for what a map like this means lets consider a more familiar map which you can think of as what COBE would have seen if it looked down instead of up The map here is a 2 dimensional representation of the 3 dimensional surface of the earth just like the COBE map is a representation of the sky COBE has rather blurry vision and can only see large features corresponding to 7 degree separations on the sky Here s what

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