Data: 18.08.2022

Palestrante: Dr. Diego Pallero (Pontificia Universidad Católica de Chile)

Link: https://youtu.be/s9NG0Pq6m0w

Resumo: One of the fundamental problems in modern astrophysics is the understanding of the role that the environment plays in the galaxy evolution. Many works, both theoretical and observational, have focused on this topic. Nevertheless, it is not clear yet which are the main physical mechanisms that lead to the cessation of star formation, or quenching, in galaxies that reside in dense environments. State-of-the-art hydrodynamical simulations are perfect tools to study the evolution of galaxies in extremely dense environments such as galaxy clusters. Using both theoretically- and empirically- based definitions to select star-forming and passive (quenched) galaxies, we separate our sample into galaxies that suffer the largest effects on their star formation histories either inside or outside the cluster. We find that > 70% of galaxies are processed before they are accreted onto the clusters regardless of the cluster mass. However, most galaxies reach their quenching state in dense environments, several gigayears after this processing event, indicating that pre-processing plays an important role in establishing the time scales and the history of star formation quenching in massive structures. On the other hand, the definitive cease of star formation is mainly driven by an environmental effect; we find that there is a minimum threshold in the gas density of the ICM, of ρ(ICM) > 10^-28 gr cm^-3 to quench the star formation of galaxies. At this density, ram pressure becomes the dominant, and galaxies rapidly get depleted from their gas component. Typically, this threshold takes place near the cluster R200, regardless of cluster’s M200.