Cosmological implications from the eROSITA all-sky survey

eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the German core instrument aboard the Russian Spektrum-Roentgen-Gamma satellite which is scheduled for launch in 2015. The main driver for eROSITA is studying the nature of dark energy, which is especially imprinted in the redshift and mass distribution of galaxy clusters. eROSITA is expected to detect around 100 thousand clusters of galaxies in X-rays up to redshifts of z∼2.0. We present forecasts for the observation power of this instrument and introduce the distribution of galaxy clusters with mass and redshift as it is expected to be observed during the all-sky survey. By means of simulations of galaxy cluster spectra, we quantify the accuracy and the precision with which eROSITA will determine the temperature of the intra-cluster medium and the cluster redshift directly from the survey data. According to these predictions, eROSITA will increase the current cluster sample with precise temperatures by a factor of 5-10. Based on the above computations and results, the constraints eROSITA will place on the cosmological parameters are predicted by means of Markov-Chain Monte Carlo simulations.