Comparing hydrodynamical simulations with observations is becoming increasingly
important for understanding the physical processes that govern galaxy evolution in the
era of JWST and ALMA.  In this talk, I will introduce SKIRT, a versatile radiative
transfer code developed by our group, for which I implemented the non-LTE line radiative
transfer module.  As a first application, I will present new radiation-hydrodynamic
simulations of AGN tori that self-consistently incorporate non-equilibrium chemistry,
XDR/PDR heating and cooling, and dust destruction under AGN conditions. These
simulations reveal how AGN radiation and supernova-driven turbulence shape the gas
distribution and chemical abundances on scales of tens of parsecs.  As a second
application, I will present synthetic UV-to-millimetre observations of galaxies at
z=3-8.5 from the MEGATRON cosmological simulations, generated with SKIRT. I will
discuss how star formation and stellar feedback shape far-infrared (FIR) emission lines
such as [O III] and [C II], and explore the physical conditions responsible for the
strong ionized emission observed in high-redshift galaxies.