Predicting the Merger Fraction of Lyman alpha Emitters from Redshift z~3
  to z~7
  Rapid mass assembly, likely from mergers or smooth accretion, has been
predicted to play a vital role in star-formation in high-redshift Lyman-alpha
(Lya) emitters. Here we predict the major merger, minor merger, and smooth
accreting Lya emitter fraction from z~3 to z~7 using a large dark matter
simulation, and a simple physical model that is successful in reproducing many
observations over this large redshift range. The central tenet of this model,
different from many of the earlier models, is that the star-formation in Lya
emitters is proportional to the mass accretion rate rather than the total halo
mass. We find that at z~3, nearly 35% of the Lya emitters accrete their mass
through major (3:1) mergers, and this fraction increases to about 50% at z~7.
This imply that the star-formation in a large fraction of high-redshift Lya
emitters is driven by mergers. While there is discrepancy between the model
predictions and observed merger fractions, some of this difference (~15%) can
be attributed to the mass-ratio used to define a merger in the simulation. We
predict that future, deeper observations which use a 3:1 definition of major
mergers will find >30% major merger fraction of Lya emitters at redshifts >3.
