Astro 250 Unit III: Cosmology
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The Expanding Universe
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observable galaxies: farther ones move away faster
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the Hubble Law: V=H d
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galaxies as tracers of expanding space
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"horizon" vs. "edge"
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distance <-> time <-> redshift
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definition of "z"
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lookback time
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age of the Universe and the Big Bang
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Extrapolating backwards: The early history of the Universe
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distant in space = distant in past
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smaller universe is a hotter universe: Tz = Tnow
(1+z)
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increasing importance of radiation at earler times
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z=1000 -> recombination epoch
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z>1000 -> opaque universe
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the cosmic background radiation
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Big Bang Nucleosynthesis
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E=mc2 ; equivalence of mass and energy
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particle and antiparticle anihilation and formation to/from photons
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start at T= infinity, as universe cools, particles "freeze out"
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freeze out of protons, neutrons
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nuclear reactions
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formation of deuterium: the deuterium bottleneck
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formation of helium (at t=3 minutes)
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deuterium, helium and lithium as probes of baryonic (ordinary matter)
density
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The Structure of the Universe
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open vs. closed vs. flat
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curved space
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density of the Universe and Omega
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fate of the universe tied to the density of the universe
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Dark Matter in the Universe
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baryonic vs nonbaryonic
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visible matter
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evidence for dark matter:
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galaxy rotation curves
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galaxy clusters
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searching for dark matter candidates
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formation of cosmic structure
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large scale clustering of galaxies
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cosmic background radiation smoothness
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wrinkles in COBE and other maps
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growth of structures: hot vs. cold dark matter
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inflation
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current topics on cosmology
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the value of the Hubble constant from HST observations
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measuring Omega from departures in the Hubble law
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acceleration and Lambda from Type Ia supernovae (runaway universe)
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precision measures of cosmological parameters by WMAP
- Polarization of the CMB observed by BICEP-2