Toward more robust numerical and observational comparisons

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This proposal lays out a program of research designed to help us further understand both the applicability and limitations of using numerical simulations of galaxy formation to help explain observational results from both a phenomenological and statistical perspective. This investigation theme is motivated by the next generation of large scale surveys that will operate in the 2020s, such as the Large Synoptic Survey Telescope and the European Euclid mission (to name but two major projects), that will provide statistical samples of galaxies of exceptional size and fidelity. ***The proposal is primarily focused on further understanding three key components of simulations: Firstly the variance of galaxy properties produced by chaos-like evolution in simulations, an issue that is growing in concern within the community. Secondly an examination of evolutionary and environmental issues within observationally derived correlations of properties of galaxies, such as the star formation rate (SFR) of a galaxy versus the inferred black hole accretion rate (BHAR), and thirdly an examination of whether the evolution of isolated dwarf system is sufficiently simple to allow star formation models to be directly constrained. ***All simulation work will be conducted using the state-of-the-art' GIZMO code, with a limited amount of development necessary to add new computational techniques. The studies of chaos will involve resimulating galaxies multiple times under varying situations to see how the level of chaos-like evolution decomposes via two separate potential channels, namely halo, and disk evolution. The disk evolution part of the analysis will be conducted using a newly developed algorithm that provides a simple measure of the local level of mixing. A complementary investigation will examine how different models of the energy return from star formation, `feedback', produce different levels of chaos, as current investigations provide contradictory results on the addition of more complex physics. The research theme focused on understanding the SFR-BHAR correlation will first examine a suite of 300 simulated clusters to focus on environmental impacts on the activity of nuclear accretion in galaxies and then move on to a larger simulation project that precisely constrains the build-up of mass in galaxy halos to determine if that can be used as means to better understand observed correlations. The star formation model constraint project will also use a suite of simulated galaxy models to conduct a sensitivity analysis of the star formation efficiency and various feedback parameters versus the epoch of cosmic reionization.***The research will be supported by an award winning outreach portfolio that will be broadened to build a collaboration with Mi'kmaq artist, Melissa Sue Labrador, who is especially interested in the cosmic evolution and relating this to indigenous ways of knowing. The PI & research group will explore with Labrador in the spirit of "Two-eyed seeing."**