  We investigate the dynamics of gaseous clumps formed via gravitational
fragmentation in young protostellar disks, focusing on the fragments that are
ejected from the disk via many-body gravitational interaction. Numerical
hydrodynamics simulations were employed to study the evolution of young
protostellar disks formed from the collapse of rotating pre-stellar cores with
mass in the 1.1-1.6 M_sun range. Protostellar disks formed in our models
undergo gravitational fragmentation driven by continuing mass loading from
parental collapsing cores. A few fragments can be ejected from the disk during
the early evolution, but the low-mass fragments (< 15~M_Jup) disperse creating
spectacular bow-type structures while passing through the disk and collapsing
core. The least massive fragment that survived the ejection (21 M_Jup)
straddles the planetary-mass limit, while the most massive ejected fragments
(145 M_Jup) can break up into several pieces, leading to the ejection of wide
separation binary clumps in the brown-dwarf mass range. About half of the
ejected fragments are gravitationally bound, the majority is supported by
rotation against gravity, and all fragments have the specific angular momentum
that is much higher than that expected for brown dwarfs. We found that the
internal structure of the ejected fragments is distinct from what would be
expected for gravitationally contracting clumps formed via cloud core
fragmentation, which can help to differentiate their origin. The ejection of
fragments is an important process inherent to massive protostellar disks, which
produces freely-floating pre-brown dwarf cores, regulates the disk and stellar
masses, and potentially enriches the intracluster medium with processed dust
and complex organics.
