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 \leq z \leq 2.9 .
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 ( \Delta \log M = -0.06 ^ { +0.06 } _ { -0.13 } , \Delta \log age _ { w } = +0.03 ^ { +0.19 } _ { -0.42 } ) .
During the merger itself , we find larger offsets : \Delta \log M = -0.13 ^ { +0.10 } _ { -0.14 } and \Delta \log age _ { w } = -0.12 ^ { +0.40 } _ { -0.26 } . E ( B - V ) values are generally recovered well , but the estimated total visual absorption A _ { V } is consistently too low , increasingly so for larger optical depths ( \Delta A _ { V } = -0.54 ^ { +0.40 } _ { -0.46 } in the merger regime ) .
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 ( \Delta \log SFR = -0.44 ^ { +0.32 } _ { -0.31 } in the merger regime ) .
The masses , ages , E ( B - V ) , A _ { V } , 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 .
Mismatch between the real and template star formation history , as is the case during the merging event , drives the age , and consequently mass estimate , down with respect to the true age and mass .
However , the larger optical depth toward young stars during this phase reduces the effect considerably .
Finally , we tested the photometric redshift code EAZY on the simulated galaxies placed at high redshift .
We find a small scatter in \Delta z / ( 1 + z ) of 0.031 .