  We consider the dynamics of two-dimensional interacting ultracold bosons
triggered by suddenly switching on an artificial gauge field. The system is
initialized in the ground state of a harmonic trapping potential. As a function
of the strength of the applied artificial gauge, we analyze the emergent
dynamics by monitoring the angular momentum, the fragmentation as well the
entropy and variance of the entropy of absorption or single-shot images. We
solve the underlying time-dependent many-boson Schr\"odinger equation using the
multiconfigurational time-dependent Hartree method for indistinguishable
particles (MCTDH-X). We find that the artificial gauge field implants angular
momentum in the system. Fragmentation -- multiple macroscopic eigenvalues of
the reduced one-body density matrix -- emerges in sync with the dynamics of
angular momentum: the bosons in the many-body state develop non-trivial
correlations. Fragmentation and angular momentum are experimentally difficult
to assess; here, we demonstrate that they can be probed by statistically
analyzing the variance of the image entropy of single-shot images that are the
standard projective measurement of the state of ultracold atomic systems.
