@presentation {1453626,
	title = {Visualizing HII Regions in FIRE Galaxy Simulations},
	journal = {American Astronomical Society Meeting Abstracts $\#$233},
	volume = {233},
	year = {2019},
	pages = {253.05},
	abstract = {In this project, we analyze the spatial structure of HII regions in the interstellar medium of galaxy formation simulations from the FIRE (Feedback in Realistic Environments) project. We focus on a simulation of a Milky Way-like galaxy at high resolution evolved with the time-dependent chemistry solver CHIMES. We compare the properties of HII regions around young, luminous stars to the spherical HII regions predicted by the Str{\"o}mgren model. To do this, we used Firefly, an interactive web-based visualization application we developed for exploring particle-based data. In addition to zooming in, rotating around, and visually manipulating the particles, we have also implemented in Firefly the ability to apply a unique colormap to each particle type based on a certain attribute. Using this new feature reveals sharp boundaries between ionized and neutral hydrogen regions, similar to what is predicted by the Str{\"o}mgren approximation. A more quantitative analysis, however, reveals that the Str{\"o}mgren radius is systematically smaller than the true "ionized radius" measured from the simulation data. We find that this is because the Str{\"o}mgren model assumes isolated stars, while in the more realistic simulations, young stars are clustered. The assumption of isolated stars underestimates the true ionizing luminosity of an HII region, causing the Str{\"o}mgren radius to be generally smaller than the true ionized radius. In the future, we plan to use Firefly to further analyze how molecular clouds (traced by H2, CO, etc.) relate to HII regions in the simulations.},
	author = {Shiferaw, Mahlet and et al}
}
