The central tenet of the FOGGIE simulations is tracing the co-evolution of galaxies and their diffuse environs. To do so, we enforce exquisite spatial resolution in the circumgalactic medium in order to capture the small-scale physics and substructure of the bulk of the gas in the galactic ecosystem. In our first generation of FOGGIE simulations, we have improved the circumgalactic resolution to be 549 comoving parsecs within ~100 kiloparsecs of the main halo, a Milky Way-like galaxy at z=0. Above: a projection of the neutral hydrogen (HI) column density at z=0.95 (6.1 billion years after the Big Bang) in one of our simulations; the colored material is optically thick to the Lyman Limit (NHI ≳ 1017.2cm-2). The width of this projection is about 100 kiloparsecs, and small dense cloudlets can clearly be seen far from the main galaxy disk.
The movie below shows the evolution in projected density, temperature, and metallicity over ~1.5 billion years in our new simulation (top) and a simulation with more traditional circumgalactic resolution (bottom). The spatial scale is 200/h comoving kiloparsecs across (about 100 physical kiloparsecs at the end of the movie).
The second pillar of the FOGGIE simulations is creating synthetic data in order to compare to, interrogate, and predict real data. Below, we show the stellar light as would be seen by Hubble and JWST for the same galaxy as evolved with a "normally" resolved (left) and with our improved (right) circumgalactic resolution at z=2 (3.3 billion years after the Big Bang). We find that with no changes to the interstellar resolution or star formation feedback physics, the morphology, kinematics, and and size of the galaxy changes dramatically.