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We use the ROSAT Deep Cluster Survey (RDCS) to trace the evolution of the cluster abundance out to $zsimeq 0.8$ and constrain cosmological models. We resort to a phenomenological prescription to convert masses into $X$-ray fluxes and apply a maximum-likelihood approach to the RDCS redshift- and luminosity-distribution. We find that, even changing the shape and the evolution on the $L_{bol}$-$T_X$ relation within the observational uncertainties, a critical density Universe is always excluded at more than $3sigma$ level. By assuming a non-evolving $X$-ray luminosity-temperature relation with shape $L_{bol}propto T_X^3$, it is $Omega_m=0.35^{+0.35}_{-0.25}$ and $sigma_8=0.76^{+0.38}_{-0.14}$ for flat models, with uncertainties corresponding to $3sigma$ confidence levels.
The ROSAT Deep Cluster Survey (RDCS) has provided a new large deep sample of X-ray selected galaxy clusters. Observables such as the flux number counts n(S), the redshift distribution n(z) and the X-ray luminosity function (XLF) over a large redshift
We study the characteristics of the galaxy cluster samples expected from the European Space Agencys Euclid satellite and forecast constraints on cosmological parameters describing a variety of cosmological models. The method used in this paper, based
We examine the likelihoods of different cosmological models and cluster evolutionary histories by comparing semi-analytical predictions of X-ray cluster number counts to observational data from the ROSAT satellite. We model cluster abundance as a fun
An unusual double-lobed extended X-ray source (RX J105343+5735) is detected in the ROSAT ultra-deep HRI image of the Lockman Hole. The angular size of the source is 1.7 X 0.7 arcmin^2 and its X-ray flux is 2 X 10^-14 erg cm^-2 s^-1. R-band imaging fr
We have constructed a large, statistically complete sample of galaxy clusters serendipitously detected as extended X-ray sources in 647 ROSAT PSPC pointed observations. The survey covers 158 square degrees with a median sample flux limit of 1.2 x 10^