Effects of multiphase gas and projection on X-ray observables in simulated galaxy clusters as seen by eROSITA

Context. Galaxy clusters are the most massive bound objects in the recent history of the universe; the number density of galaxy clusters as a function of mass and redshift is a sensitive function of the cosmological parameters. To use clusters for cosmological parameter studies, it is necessary to determine their masses as accurately as possible, which is typically done via scaling relations between mass and observables. Aims. X-ray observables can be biased by a number of effects, including multiphase gas and projection effects, especially in the case where cluster temperatures and luminosities are estimated from single-model fits to all of the emission with an overdensity radius such as r500c. Using simulated galaxy clusters from a realistic cosmological simulation, our aim is to determine the importance of these biases in the context of Spectrum-Roentgen-Gamma/eROSITA observations of clusters. Methods. We extracted clusters from the Box2_h