4.3.4. Some Measured Values for M / L

When measuring M / L it is convenient to refer to a common band. In what follows, we choose the blue band as the L reference. The determination of M / L depends on distance as M goes as V_c² R and L goes as 4 R² F_g where F_g is the observed flux (photons per cm² sec^-1). For reference, the global M / L required to close the Universe for our probable range of H₀ is 2000 in the B-band. The stellar population of the solar neighborhood has M / L 2. A 10 Gyr solar metallicity population with x in the range 1-1.5 has M / L 10. We therefore arrive at a very significant conclusion: If the Universe is closed, then the luminous portions of galaxies contribute at most 10/2000 = 0.5% of the closure density.

The derived values of M / L from analysis of rotation curves, X-ray halos and binary galaxies consistently give results in the range of 10 - 200. Most spiral galaxies average around 10-30 when r is restricted to 3-4 r_h. This means that if the Universe is closed, then the combined light + dark mass in galaxies contributes only 10% (at most) of the closure density. On the other hand, if can be determined to be 0.1 (see below) then its conceivable that all the mass in the Universe is located in the halos that define the potential wells of galaxies.