A simulation of an idealized, isolated Milky Way-like disk galaxy, seen in three views. Each shows the light escaping from the galaxy at a particular wavelength, computed in post-processing using a Monte Carlo radiative transfer code. From left to right: ionizing radiation, the H-alpha transition of hydrogen, and the Lyman-alpha transition of hydrogen. Ionizing photons are primarily emitted around young stars, but are only visible if these regions break out of the disk mid-plane. On the other hand, H-alpha reveals the reprocessing of this radiation due to dust scattering and absorption, while Lyman-alpha additionally includes the impact of resonant line transfer. The top row shows face-on views of the disk, while the bottom row shows edge-on views. Each panel is 50 kpc across.

Methods: AREPO, COLT codes