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Unformatted text preview: Phys/Astro 228: Extragalactic Astronomy and Cosmology December 1 2006 C.P. Ma Problem Set 9 Due in class Friday Dec 8 Readings: Ch 6 & 8 of Dodelson 1. Time Evolution of the Baryonic Jeans Mass (a) In the radiationdominated era, show that the baryonic Jeans mass evolves with the scale factor a as M J ( a ) a 1 . Find the value for 1 , and estimate M J (in M ) at matterradiation equality time using current cosmological parameters. (b) After photon decoupling, show that the baryonic Jeans mass evolves as M J ( a ) a 2 . Find the value for 2 , and estimate M J (in M ) right after decoupling. Compare your numbers in (a) and (b) and comment on the implications. 2. TwoPoint Correlation Function The twopoint correlation function of the density perturbation field, ( vectorx ) ( vectorx ) / 1, is defined as ( r ) = ( ( vectorx 1 ) ( vectorx 2 ) ) , r =  vectorx 1 vectorx 2  . (1) The power spectrum of the mass density field is defined as...
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This note was uploaded on 08/01/2008 for the course ASTRO 228 taught by Professor Chungpeima during the Fall '06 term at University of California, Berkeley.
 Fall '06
 CHUNGPEIMA
 Cosmology

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