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Unformatted text preview: magnitude? b. Use the ﬁgure to measure an approximate slope for the counts fainter than the your magnitude limit from part a). c. The departure of the slope from a value of 0.6 could be due to a non-uniform density of galaxies or to a change of galaxy luminosity with distance (or both). Assume that the density of galaxies is constant but that the luminosity of a galaxy changes with distance as L = L ( r/r ) a . This is an approximate way to account for the changing apparent luminosities of galaxies due to redshift and/or the evolution of the stars in the galaxies. Repeat the derivation given in class to determine how the galaxy counts will change with magnitude when the luminosity changes in this way and then ﬁnd the value for the parameter a implied by your measured slope from b)....
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- Fall '08
- Big Bang, absolute magnitude, Ryden problem, Liske