Morphologies of local Lyman break galaxy analogs II: A Comparison with
  galaxies at z=2-4 in ACS and WFC3 images of the Hubble Ultra Deep Field
  Lyman break galaxies (LBGs) display a range in structures (from
single/compact to clumpy/extended) that is different from typical local
star-forming galaxies. Recently, we have introduced a sample of rare, nearby
(z<0.3) starbursts that appear to be good analogs of LBGs. These "Lyman Break
Analogs" (LBAs) provide an excellent training set for understanding starbursts
at different redshifts. We present an application of this by comparing the
rest-frame UV/optical morphologies of 30 LBAs with those of sBzK galaxies at
z~2, and LBGs at z~3-4 in the HUDF. The UV/optical colors and sizes of LBAs and
LBGs are very similar, while the BzK galaxies are somewhat redder and larger.
There is significant overlap between the morphologies (G, C, A and M_20) of the
local and high-z samples, although the latter are somewhat less concentrated
and clumpier. We find that in the majority of LBAs the starbursts appear to be
triggered by interactions/mergers. When the images of the LBAs are degraded to
the same sensitivity and resolution as the images of LBGs and BzK galaxies,
these relatively faint asymmetric features are no longer detectable. This
effect is particularly severe in the rest-frame UV. It has been suggested that
high-z galaxies experience intense bursts unlike anything seen locally,
possibly due to cold flows and instabilities. In part, this is based on the
fact that the majority (~70%) of LBGs do not show morphological signatures of
mergers. Our results suggest that this evidence is insufficient, since a large
fraction of such signatures would likely have been missed in current
observations of z>2 galaxies. This leaves open the possibility that clumpy
accretion and mergers remain important in driving the evolution of these
starbursts, together with rapid gas accretion through other means.
