The anatomy of a star-forming galaxy II: FUV heating via dust

Far-ultraviolet (FUV) radiation greatly exceeds UV, supernovae (SNe), and winds in the energy budget of young star clusters but is poorly modelled in galaxy simulations. We present results of the first isolated galaxy disc simulations to include photoelectric heating of gas via dust grains from FUV radiation self-consistently, using a ray-tracing approach that calculates optical depths along the source-receiver sightline. This is the first science application of the TREVR radiative transfer algorithm. We find that FUV radiation alone cannot regulate star formation. However, FUV radiation produces warm neutral gas and is able to produce regulated galaxies with realistic scale heights. FUV is also a long-range feedback and is more important in the outer discs of galaxies. We also use the superbubble feedback model, which depends only on the SN energy per stellar mass, is more physically realistic than common, parameter-driven alternatives and thus better constrains SN feedback impacts. FUV and SNe together can regulate star formation without producing too much hot ionized medium and with less disruption to the interstellar medium compared to SNe alone.