R144 : a very massive binary likely ejected from R136 through a
  binary-binary encounter
  R144 is a recently confirmed very massive, spectroscopic binary which appears
isolated from the core of the massive young star cluster R136. The dynamical
ejection hypothesis as an origin for its location is claimed improbable by Sana
et al. due to its binary nature and high mass. We demonstrate here by means of
direct N-body calculations that a very massive binary system can be readily
dynamically ejected from a R136-like cluster, through a close encounter with a
very massive system. One out of four N-body cluster models produces a
dynamically ejected very massive binary system with a mass comparable to R144.
The system has a system mass of $\approx$ 355 Msun and is located at 36.8 pc
from the centre of its parent cluster, moving away from the cluster with a
velocity of 57 km/s at 2 Myr as a result of a binary-binary interaction. This
implies that R144 could have been ejected from R136 through a strong encounter
with an other massive binary or single star. In addition, we discuss all
massive binaries and single stars which are ejected dynamically from their
parent cluster in the N-body models.
