Resolving observable features of galaxy cluster merger 'El Gordo' using
  idealized cluster models in SPH simulations
  The merger scenario of two galaxy subclusters to form the massive galaxy
cluster 'El Gordo' is investigated using smoothed particle hydrodynamics (SPH)
simulations. Idealized cluster models are used to initialize the states of both
subclusters prior to the merger, assuming the commonly used Navarro-Frenk-White
(NFW) dark matter (DM) density profile and solving the hydrostatic equilibrium
equation for a ${\beta}$-model with ${\beta}$ = 0.6 to obtain the gas density
profile. The impact parameter (P) and zero-energy orbit fraction (${\epsilon}$)
of the two merging subclusters are varied to put constraints on the space of
parameter values which result in projections of X-ray luminosity,
Sunyaev-Zel'dovich (SZ) effect, and DM density that correlate well with
observational features of 'El Gordo'. We are able to reproduce the remarkable
wake-like feature seen in X-ray observations that trails after the secondary
(bullet) subcluster as well as the rough shape of the combined cluster with P ~
800 kpc and ${\epsilon}$ = 0.6, which corroborate the results of prior
simulations that support an off-axis, high-speed collision as the merger
scenario. We argue that the large separation distance between the mass centers
of the two subclusters in this merger scenario may be resolved by finding a
better fit for other parameters in the idealized subcluster models.
