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We present high-resolution hydrodynamical simulations of isolated dwarfgalaxies including self-gravity, non-equilibrium cooling and chemistry,interstellar radiation fields (IRSF) and shielding, star formation, and stellarfeedback. This includes spatially and temporally varying photoelectric (PE)heating, photoionization, resolved supernova (SN) blast waves and metalenrichment. A new flexible method to sample the stellar initial mass functionallows us to follow the contribution to the ISRF, the metal output and the SNdelay times of individual massive stars. We find that SNe play the dominantrole in regulating the global star formation rate, shaping the multi-phaseinterstellar medium (ISM) and driving galactic outflows. Outflow rates (withmass-loading factors of a few) and hot gas fractions of the ISM increase withthe number of SNe exploding in low-density environments where radiative energylosses are low. While PE heating alone can suppress star formation slightlymore (a factor of a few) than SNe alone can do, it is unable to drive outflowsand reproduce the multi-phase ISM that emerges naturally when SNe are included.These results are in conflict with recent results of Forbes et al. whoconcluded that PE heating is the dominant process suppressing star formation indwarfs, about an order of magnitude more efficient than SNe. Potential originsfor this discrepancy are discussed. In the absence of SNe and photoionization(mechanisms to disperse dense clouds), the impact of PE heating is highlyoverestimated owing to the (unrealistic) proximity of dense gas to theradiation sources. This leads to a substantial boost of the infrared continuumemission from the UV-irradiated dust and a far infrared line-to-continuum ratiotoo low compared to observations. Though sub-dominant in regulating starformation, the ISRF controls the abundance of molecular hydrogen viaphotodissociation.

Variable interstellar radiation fields in simulated dwarf galaxies: supernovae versus photoelectric heating