Prof. Dr. Thomas Reiprich, Invited Lecture, Cosmology Day Workshop, Bielefeld, Germany:
Massive galaxy clusters are the youngest and, therefore, most massive objects in the Universe. Their dark matter-dominated gravitational potential wells are filled with gas, heated to 10s of millions of Kelvin by shocks and compression. The SRG/eROSITA X-ray space telescope recently surveyed the sky, hunting for this hot gas in clusters, detecting an unprecedentedly large number. Employing weak gravitational lensing to constrain cluster masses, tight constraints on, e.g., dark energy and the sum of neutrino masses have been obtained. Furthermore, eROSITA has started detecting the missing normal matter (“baryons”), hiding in the so-called warm-hot intergalactic medium (WHIM) in filaments around nearby galaxy clusters. In this talk, I’ll provide an overview of galaxy clusters, eROSITA and its measurements, and the resulting constraints on dark baryons, dark matter, and dark energy.
