lecture16

lecture16 - Cosmic evolution of galaxies, clusters &...

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Frst galaxies form when ? verify hierarchical gal. formation ? dark matter looking to greater distances ==> looking back in time ==> critical to estimate distances need a standard ‘candle’ or yardstick
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Primary Galaxy Distances : Cepheid Variable stars -- have a well-defned relation between period and luminosity -- 1 kpc to 50 Mpc Supernovae -- 1 Mpc to 1 Gpc
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Secondarily (at larger distance) , use velocities associated w/ large-scale expansion of universe : Edwin Hubble discovered : distant galaxies all moving away (from doppler shift) and , linear correlation between distance and recession speed e.g. 2 times farther => twice as fast
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uniformly expanding universe -- ie. an explosion w/ everything originating from the same place at same time in past Hubble Expansion Law What time ? T = R / V = 1 / H 0 = 10 6 pc (3.08 x 10 13 km / pc) / 72 = 4.3 x 10 17 sec = 14 x 10 9 yr Expansion age of universe !! ==> V = H
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This note was uploaded on 09/25/2010 for the course AY 106 taught by Professor Schrerr during the Winter '09 term at UMBC.

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lecture16 - Cosmic evolution of galaxies, clusters &...

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