We show the results of a study into the performance of the E-ELT integral field spectrograph
HARMONI for observations of galaxies at 2 < z < 4. Using the instrument simulation
pipeline HSIM, we performed mock observations of galaxies in this redshift range using
two different methods: (i) passive galaxies modeled with simple analytical spatial
pro files and star formation histories; and (ii) a single z = 3 galaxy extracted from
a high-resolution cosmological simulation, with a more complex and physically representative
morphology and star formation history. We describe the software tools developed to
convert the simulation data into a spectral cube containing the spatial and spectral
properties of the galaxys light. From the mock observations we estimate how well the
intrinsic properties of the galaxy can be recovered using commonly used analysis tools.
The HSIM pipeline also allows us to study observational biases and their likely impact
on the data. We discuss the implications of the project for the future science with
HARMONI in the critical redshift regime for mass assembly in galaxies.
