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Unformatted text preview: Ph 444 Problem Set 7 Due: Friday, November 19, 2010 1. Ryden problem 9.3 (Imagine that at the time of recombination, the baryonic portion of the universe consisted entirely of 4 He...) A slightly tricky point here is what to use for n baryon when calculating = n baryon /n . To keep numerically equal to that for the case with pure hydrogen, use n baryon = 4( n He + n He + ). 2. Ryden problem 9.5 (We know from observations that the intergalactic medium is currently ionized...) 3. The program CMBFAST was developed by U. Zeljak and M. Zaldarriaga to pre- dict the anisotropies of the CMB given the properties of the inhomogeneities of the universe at the surface of last scattering and the other parameters that describe the universe. It is the program used by most professionals for this purpose. It integrates over the sources of radiation along each line of sight, taking into account the geom- etry and expansion of the universe. The output is the power-spectrum of intensity fluctuations in the CMB (the...
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- Fall '08