First Results from the eROSITA All-Sky Survey: An Open Window to Precision Cluster Cosmology and Astrophysics

Galaxy clusters, representing the peaks in the cosmic density field, serve as an independent and powerful tool for investigating the evolution of cosmic structures and advancing our understanding of cosmology. The strategic identification of these clusters through multi-wavelength surveys is essential for scrutinizing gravitational theory, general relativity, and cosmological models. A significant milestone was achieved with the successful launch of eROSITA in July 2019. This German-built eROSITA X-ray telescope, on board the Russian-German Spectrum-RG (SRG) mission, operates within the 0.2-8 keV range and has produced the largest ICM-detected catalogs of galaxy clusters and groups through its All-Sky Surveys. The first eROSITA all-sky survey, with over 10,000 confirmed clusters in the Western Galactic Hemisphere, plays a pivotal role in refining cosmological parameters. Combined with the data from optical surveys like DESI Legacy, DES, HSC, and KIDS, it constrains these parameters at a percent level through the evolution of the cluster mass function. In this talk, I will outline the constraints on fundamental cosmological parameters, neutrino masses, and general relativity derived from the groundbreaking first eROSITA All-Sky Survey. Notably, this survey represents a significant leap forward, exhibiting a 5-9 times improvement compared to previous cluster surveys. Additionally, I will present eROSITA’s significant detection of warm baryons within cosmic filaments identified by optical surveys and in groups and the implications for our understanding of AGN feedback. I will summarize the value-added products made available to the community by the eROSITA consortium’s data release.