On the baryon content of the Shapley Supercluster

Abstract

The Shapley Supercluster is particularly rich in baryons, since it contains many X-ray luminous clusters. Using the relationship between X-ray luminosity and gas mass within 3 h(50) -1 Mpc radius found for nearby clusters, it is shown that the ratio of the baryon density to the critical density in the 37 h(50) -1 Mpc core of the supercluster Ω b > 0.18 h(50) −1.3 . This is much larger than the value obtained from published calculations of cosmic nucleosynthesis, Ω b = 0.06 h(50) −2 .