A new study has investigated the stability and formation mechanisms of solitonic boson stars, hypothetical objects composed of gravitationally bound bosons. The work extends previous analyses on the radial stability of these stars, incorporating nonlinear evolution under aspherical perturbations and simulating their formation from the collapse of scalar clouds. The results are particularly relevant for models that, despite having positive binding energy (which would normally suggest an energetically preferred dispersion of scalar matter), had been previously identified as radially stable.

The analysis of 3+1 dimensional evolutions found no evidence of non-radial instability in any of the radially stable models, including those with positive binding energy. However, the study suggests that these models with positive binding energy do not generically form via the gravitational cooling process. This implies that, although theoretically stable, their natural formation pathway might be limited or nonexistent under certain conditions.

Additionally, the research revealed the possible formation of another type of compact object that exhibits long-lasting radial oscillations, which prevents its classification as a stationary boson star. It is proposed that these objects could be characterized by energetically favored multi-oscillating solutions to the Einstein-Klein-Gordon equations, present in specific regions of the parameter space. This finding opens new avenues for understanding the diversity of compact objects that could arise from scalar fields.