  The goal of this study is to conduct a timely analysis of the high-redshift
star-forming galaxy populations, which will be informative in designing
next-generation experiments and their extragalactic targets. We use the
hydrodynamical simulation MillenniumTNG (MTNG) to model Lyman-alpha Emitting
(LAE) galaxies to extract key properties such as their clustering and
occupation statistics. We define LAEs through an empirical relation between
star formation rate (SFR) and Lyman-alpha flux. We also explore two other
definitions, finding that imposing an additional cut on the maximum stellar
mass of the galaxy sample, which approximates the effect of a low escape
fraction at high halo mass, leads to a 5-10\% decrease of the linear bias of
the population. As expected, we find that the HOD mass parameters rapidly
decrease with increasing number density. Additionally, the HOD parameter
$\sigma$ also decreases with number density, implying that the SFR-halo mass
relationship becomes tighter for low-luminosity objects. Surprisingly, the
non-linear clustering, estimated by the parameter $r_0$, is fixed at fixed
number density, whereas the linear bias parameter varies with redshift as $b(z)
\propto (1 + z)$, suggesting that our LAE samples are relatively stable and
long-lived. Finally, we study the amount of galaxy assembly bias present at $z
= 2, \ 3$ and find that while at $z = 2$ it is roughly $\lesssim$10\%, at $z =
3$ it decreases significantly to $\lesssim$5\%. This suggests that assembly
bias effects become less important at high $z$ likely due to the lower number
of cumulative two-halo interactions (mergers, splashback, stripping, etc.).
While our study is based on a single full-physics simulation, we expect our
results to reflect the properties of LAEs in the Universe. We demonstrate that
our findings are in good agreement with previous results using both
observations and simulations.
