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Given the following expression for an NFW potential, use Poisson's equation in spherical polar coordinates to derive a corresponding expression for the circular velocity. 111(1 + Va) 7 a Using your expression, for a Milky Way scale radius of a=15kpc, and a density at the scale radius of pr. = 0.01 Me/pc3, estimate the velocity of H1 gas in the outer parts of our Galaxy. Use published data to verify your answer, giving the reference(s) you use. dam = 4Ipo0a2