The extent of gravitationally bound structure in a {\Lambda}CDM universe
  A new analytical model for constraining the extent of gravitationally bound
structure in the Universe is presented. This model is based on a simple
modification of the spherical collapse model (SCM), and its performance in
predicting the limits of bound structure in N-body simulations is compared to
that of two previous models with the aid of new software named COLDGaS--
compute unified device architecture (CUDA) object location determination in
GADGET2 snapshots -- which was developed by the author. All of these models can
be distilled down to a single unique parameter {\xi}, here named the critical
parameter, which was found to have values of 3 and 1.18 from the previous
studies, and a value of 1.89 from the modified SCM. While still on the
conservative side, this new model tends to better identify what structure is
gravitationally bound in simulations. All three analytical models are applied
to the Corona Borealis supercluster, with the modified SCM and {\xi} = 1.18
model making predictions that are in agreement with recent work showing that
A2056, A2061, A2065, A2067, and A2089 comprise a gravitationally bound
supercluster. As an additional test, the modified SCM is used to estimate the
mass within the turn around radius of the Virgo cluster, providing results in
good agreement with studies relating the virial mass of clusters to the total
mass within turn around.
