Collaborative Research: Constraining galaxy cluster merger dynamics with hydrodynamical simulations and novel multi-probe observations of 10 objects

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Clusters of galaxies are key players in unraveling the mysteries behind galaxy formation and evolution, and understanding such mysteries is necessary to uncover how our Universe evolved and to learn how our own Milky Way Galaxy began. The goal of this project is to better understand the primary growth mechanism of the largest bound objects in our Universe: major mergers between galaxy clusters of similar masses. Deep, multi-probe observational data and advanced hydrodynamical computer simulations are required. This project aims to significantly advance our knowledge through the study of ten galaxy clusters. This project will also strengthen the US science workforce by directly training a graduate student and postdoctoral researcher in general and computational astrophysics. Project plans also include a vigorous education and public outreach program. Specifically, the investigators will advance discovery and understanding via regular visits to Gabrielino High School (San Gabriel, CA); broaden participation of underrepresented groups by hosting students from Gabrielino High School via the Summer Research Connection at Caltech, as well as undergraduates from colleges around Eastern Massashuetts via the Latino Initiative Program at the Smithsonian Institution Astrophysical Observatory; and enhance infrastructure for research and education by accessing the demonstration resources available from Caltech for visits to Gabrielino High School. The analysis will focus on ten objects that have gravitational lensing models from Hubble Space Telescope to map the plane-of-sky (POS) projected total mass density; X-ray spectroscopic imaging to map the POS ICM emissivity and temperature; cluster-member spectroscopy to map the line of sight (LOS) velocity of the dark matter; and Sunyaev-Zel’dovich effect data to map the LOS velocity and projected density of the ICM. The investigators will have complete information about the POS morphology and LOS velocity of both the dark matter and the ICM gas. They will compare with mock observations of custom hydrodynamical merger simulations produced specifically for this project. The end result will be a robust constraint on the merger geometry of each galaxy cluster in their sample that will enable a search for new dynamical processes and an assessment of population statistics for the sample.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.