A deficit of high-redshift, high-luminosity X-ray clusters: Evidence for ahigh value of Omega(m)?

From the Press-Schechter mass function and the empirical X-ray cluster lumi nosity-temperature (LT) relation, we construct an X-ray cluster luminosity function that can be applied to the growing number of high-redshift, X-ray cluster luminosity catalogs to constrain cosmological parameters. In this p aper, we apply this luminosity function to the Einstein Medium Sensitivity Survey (EMSS) and the ROSAT Brightest Cluster Sample (BCS) luminosity funct ion to constrain the value of Omega(m). In the case of the EMSS, we find a factor of 4-5 fewer X-ray clusters at redshifts above z = 0.4 than below th is redshift at luminosities above L-x = 7 x 10(44) ergs s(-1) (0.3-3.5 keV) , which suggests that the X-ray cluster luminosity function has evolved abo ve L-star. At lower luminosities, this luminosity function evolves only min imally, if at all. Using Bayesian inference, we find that the degree of evo lution at high luminosities suggests that Omega(m) = 0.96(-0.32)(+0.36), gi ven the best-fit L-T relation of Reichart, Castander, & Nichol. When we acc ount for the uncertainty in how the empirical L-T relation evolves with red shift, we find that Omega(m) approximate to 1.0 +/- 0.4. However, it is unc lear to what degree systematic effects may affect this and similarly obtain ed results.