Cosmological Simulations of the Formation of Dark Matter Cores and Bulgeless Galaxies

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ABSTRACTAST-1108885GovernatoUnderstanding the physical processes that shape the formation and evolution of galaxies is a fundamental question in modern astrophysics. This project will run simulations with high resolution and physical detail in a full Cold Dark Matter (CDM) cosmological context, studying this problem with a strong emphasis on galaxy centers. The work focuses on three closely interconnected discrepancies between predictions of the CDM model and the observed evidence for i) dark matter cores at the centers of small galaxies, ii) the large fraction of bulgeless dwarfs, and iii) the existence of massive disk galaxies with very small (pseudo) bulges. The simulations share three common features: i) a simple yet physically motivated description of star formation, ii) gas outflows driven by energy feedback from supernovae and supermassive black holes, and iii) star formation quenching by ultraviolet photons. These simulations will resolve the inner structure of galaxies down to fifty parsecs over the entire Hubble time. This approach will relate directly the spatial distribution and physical properties of the particles in the N-Body simulations to the quantities actually measured for real galaxies, using software to "observe" the models, including physical effects as well as the known properties of instruments, to create realistic artificial datasets.This team has already used this approach to obtain seminal results on the formation of bulgeless galaxies with dark matter cores, and to simulate a cosmological set of galaxies that simultaneously reproduce the luminosity-size relation, the abundance of damped Lyman alpha systems, and the HI Tully-Fisher relation. Specific goals of this new work include understanding how gas outflows create dark matter cores at the centers of galaxies and predicting their size over a range of galaxy masses and merging and star formation histories, understanding the role of gas outflows, mergers and various dynamical instabilities in the central region of galaxies on the creation or suppression of stellar bulges and pseudo bulges, and predicting the observable photometric and kinematic properties of the baryonic mass distribution in galaxies.The PI will collaborate with his institution's funded Pre-Major in Astronomy Program (Pre-MAP), which helps underrepresented students in their transition to college and possibly to an astronomy major, providing them with academic advising and one to one mentorship while guiding them through research projects. The present study will provide research projects for Pre-MAP students and tutoring and support for undergraduates linked to the program.