Evolution of Massive Galaxy Structural Properties and Sizes via Star
  Formation In the GOODS NICMOS Survey
  We present a study of the resolved star-forming properties of a sample of
distant massive M_*>10^11M_solar galaxies in the GOODS NICMOS Survey (GNS). We
derive dust corrected UV star formation rates (SFRs) as a function of radius
for 45 massive galaxies within the redshift range 1.5<z<3 in order to measure
the spatial location of ongoing star formation. We find that the star formation
rates present in different regions of a galaxy reflect the already existent
stellar mass density, i.e. high density regions have higher star formation
rates than lower density regions, on average. This observed star formation is
extrapolated in several ways to the present day, and we measure the amount of
new stellar mass that is created in individual portions of each galaxy to
determine how the stellar mass added via star formation changes the observed
stellar mass profile, the Sersic index (n) and effective radius (R_e) over
time. We find that these massive galaxies fall into three broad classifications
of star formation distribution. These different star formation distributions
increase the effective radii over time, which are on average a factor of
~16pm5% larger, with little change in n (average Delta n=-0.9pm0.9) after
evolution. We also implement a range of simple stellar migration models into
the simulated evolutionary path of these galaxies in order to gauge its effect
on the properties of our sample. This yields a larger increase in the evolved
R_e than the pure static star formation model, with a maximum average increase
of Delta R_e~54pm19%, but with little change in n, Delta n ~-1.1pm1.3. These
results are not in agreement with the observed change in the R_e and n between
z~2.5 and 0 obtained via various observational studies. We conclude that star
formation and stellar migration alone cannot account for the observed change in
structural parameters for this galaxy population (abridged).
