Simulated Galaxy Interactions as Probes of Merger Spectral Energy
  Distributions
  We present the first systematic comparison of ultraviolet-millimeter spectral
energy distributions (SEDs) of observed and simulated interacting galaxies. Our
sample is drawn from the Spitzer Interacting Galaxy Survey, and probes a range
of galaxy interaction parameters. We use 31 galaxies in 14 systems which have
been observed with Herschel, Spitzer, GALEX, and 2MASS. We create a suite of
GADGET-3 hydrodynamic simulations of isolated and interacting galaxies with
stellar masses comparable to those in our sample of interacting galaxies.
Photometry for the simulated systems is then calculated with the SUNRISE
radiative transfer code for comparison with the observed systems. For most of
the observed systems, one or more of the simulated SEDs match reasonably well.
The best matches recover the infrared luminosity and the star formation rate of
the observed systems, and the more massive systems preferentially match SEDs
from simulations of more massive galaxies. The most morphologically distorted
systems in our sample are best matched to simulated SEDs close to coalescence,
while less evolved systems match well with SEDs over a wide range of
interaction stages, suggesting that an SED alone is insufficient to identify
interaction stage except during the most active phases in strongly interacting
systems. This result is supported by our finding that the SEDs calculated for
simulated systems vary little over the interaction sequence.
