  We present high-resolution hydrodynamical simulations of isolated dwarf
galaxies including self-gravity, non-equilibrium cooling and chemistry,
interstellar radiation fields (IRSF) and shielding, star formation, and stellar
feedback. This includes spatially and temporally varying photoelectric (PE)
heating, photoionization, resolved supernova (SN) blast waves and metal
enrichment. A new flexible method to sample the stellar initial mass function
allows us to follow the contribution to the ISRF, the metal output and the SN
delay times of individual massive stars. We find that SNe play the dominant
role in regulating the global star formation rate, shaping the multi-phase
interstellar medium (ISM) and driving galactic outflows. Outflow rates (with
mass-loading factors of a few) and hot gas fractions of the ISM increase with
the number of SNe exploding in low-density environments where radiative energy
losses are low. While PE heating alone can suppress star formation slightly
more (a factor of a few) than SNe alone can do, it is unable to drive outflows
and reproduce the multi-phase ISM that emerges naturally when SNe are included.
These results are in conflict with recent results of Forbes et al. who
concluded that PE heating is the dominant process suppressing star formation in
dwarfs, about an order of magnitude more efficient than SNe. Potential origins
for this discrepancy are discussed. In the absence of SNe and photoionization
(mechanisms to disperse dense clouds), the impact of PE heating is highly
overestimated owing to the (unrealistic) proximity of dense gas to the
radiation sources. This leads to a substantial boost of the infrared continuum
emission from the UV-irradiated dust and a far infrared line-to-continuum ratio
too low compared to observations. Though sub-dominant in regulating star
formation, the ISRF controls the abundance of molecular hydrogen via
photodissociation.
