Luminosity density estimation from redshift surveys and the mass density of the Universe
نویسنده
چکیده
In most direct estimates of the mass density (visible or dark) of the Universe, a central input parameter is the luminosity density of the Universe. Here we consider the measurement of this luminosity density from red-shift surveys, as a function of the yet undetermined characteristic scale RH at which the spatial distribution of visible matter tends to a well defined homogeneity. Making the canonical assumption that the cluster mass to luminosity ratio M/L is the universal one, we can estimate the total mass density as a function Ωm(RH ,M/L). Taking the highest estimated cluster value M/L ≈ 300hM⊙/L⊙ and a conservative lower limit RH ∼> 20h Mpc, we obtain the upper bound Ωm ∼< 0.1 . We note that for values of the homogeneity scale RH in the range RH ≈ (90 ± 45)hMpc, the value of Ωm may be compatible with the nucleosynthesis inferred density in baryons. Subject headings: galaxies: general; galaxies: statistics; cosmology: large-scale structure of the universe
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