How galaxies acquire their gas: perspectives from modern cosmological simulations

Dylan Nelson (CfA Harvard) - November 24, 2014 at 12:10 pm

Despite significant progress with numerical simulations over the past decade, the process by which galaxies acquire their baryonic matter through cosmic time remains poorly understood. I examine this question with a series of cosmological hydrodynamical simulations, in the context of the moving-mesh code Arepo and the Illustris simulation project. First, I will describe the "Monte Carlo tracer particle" technique we developed to follow the Lagrangian history of gas in grid-based simulations. Then, I will re-examine how galaxies accrete gas from the intergalactic medium, contrasting our findings to earlier simulations which identified 'cold flows' or 'cold mode accretion' as a primary driver of galaxy growth. Next, I will discuss how the inclusion of a comprehensive model for baryonic feedback processes changes the nature and rate of cosmological gas accretion. In this context we identify several key differences with respect to simple theoretical assumptions commonly employed in semi-analytical models of galaxy formation. I will conclude with some ongoing work -- a suite of single object, high-resolution "zooms" which exquisitely resolve the gas-dynamics of the circumgalactic regime and the interaction between filamentary inflow from the IGM and the quasi-static hot halo atmosphere.

The seminar will be held in 131A Campbell Hall.

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