Early Results from the First eROSITA All Sky Cluster Survey
Max Planck Institute for Extraterrestrial Physics
Successfully launched in July 2019, eROSITA, the German-built telescope array operating between 0.3-8 keV on board the Russian-German Spectrum-RG (SRG) mission, provides a unique imaging, spectroscopic, and timing capability. The high sensitivity, large field of view, and high survey efficiency of eROSITA is bound to revolutionize X-ray astronomy. By performing eight all-sky surveys, each lasting half a year in the next four years, eROSITA will deliver the largest catalogs of X-ray sources. Clusters of galaxies trace the highest peaks in the cosmic density field and offer an independent and powerful probe of the growth of structure. The final eROSITA All-Sky Survey catalog with more than 100,000 clusters will map the large-scale structure and put us on the verge of a breakthrough in precision measurements of the cosmological parameters. I will briefly mention the main results of the performance verification phase survey (eFEDS). Then I will review some preliminary results from the first eROSITA All-Sky Survey, presenting, in particular, the properties of clusters and groups of galaxies detected in the first All-Sky survey and the projected constraints on cosmology.