  Radiatively inefficient accretion flows (RIAFs) are believed to power
supermassive black holes (SMBH) in the underluminous cores of galaxies. Such
black holes are typically accompanied by flat-spectrum radio cores indicating
the presence of moderately relativistic jets. One of the best constrained RIAFs
is associated with the SMBH in the Galactic center, Sgr A*. Since the plasma in
RIAFs is only weakly collisional, the dynamics and the radiative properties of
these systems are very uncertain. Here we want to study the impact of varying
electron temperature on the appearance of accretion flows and jets. Using 3-D
GRMHD accretion flow simulations, we use ray tracing methods to predict spectra
and radio images of RIAFs allowing for different electron heating mechanisms in
the in- and outflowing parts of the simulations. We find that small changes in
the electron temperature can result in dramatic differences in the relative
dominance of jets and accretion flows. Application to Sgr A* shows that radio
spectrum and size of this source can be well reproduced with a model where
electrons are more efficiently heated in the jet. The X-ray emission is
sensitive to the electron heating mechanism in the jets and disk and therefore
X-ray observations put strong constraints on electron temperatures and geometry
of the accretion flow and jet. For Sgr A*, the jet model also predicts a
significant frequency-dependent core shift which could place independent
constraints on the model once measured accurately. We conclude that more
sophisticated models for electron distribution functions are crucial for
constraining GRMHD simulations with actual observations. For Sgr A*, the radio
appearance may well be dominated by the outflowing plasma. Nonetheless, at the
highest radio frequencies, the shadow of the event horizon should still be
detectable with future Very Long Baseline Interferometric observations.
