  We present a detailed analysis of our ability to determine stellar masses,
ages, reddening and extinction values, and star formation rates of
high-redshift galaxies by modeling broad-band SEDs with stellar population
synthesis. In order to do so, we computed synthetic optical-to-NIR SEDs for
model galaxies taken from hydrodynamical merger simulations placed at redshifts
1.5 < z < 3. Viewed under different angles and during different evolutionary
phases, the simulations represent a wide variety of galaxy types (disks,
mergers, spheroids). We show that simulated galaxies span a wide range in SEDs
and color, comparable to these of observed galaxies. In all star-forming
phases, dust attenuation has a large effect on colors, SEDs, and fluxes. The
broad-band SEDs were then fed to a standard SED modeling procedure and
resulting stellar population parameters were compared to their true values.
Disk galaxies generally show a decent median correspondence between the true
and estimated mass and age, but suffer from large uncertainties. During the
merger itself, we find larger offsets (e.g., log M_recovered - log M_true =
-0.13^{+0.10}_{-0.14}). E(B-V) values are generally recovered well, but the
estimated total visual absorption Av is consistently too low, increasingly so
for larger optical depths. Since the largest optical depths occur during the
phases of most intense star formation, it is for the highest SFRs that we find
the largest underestimates. The masses, ages, E(B-V), Av, and SFR of merger
remnants (spheroids) are very well reproduced. We discuss possible biases in
SED modeling results caused by mismatch between the true and template star
formation history, dust distribution, metallicity variations and AGN
contribution.
