Boson stars have a long history as candidates for all manner of phenomena, from fundamental particle, to galactic dark matter. A huge variety of solutions have been found and their dynamics studied. Mathematically, BS are fascinating soliton-like solutions. Astrophysically, they represent possible explanations of black-hole candidates and dark matter, with observations constraining BS properties.
Further constraints appear to be right around the corner in a few directions. The LHC is rapidly narrowing the possible mass range for a Higgs particle (the quantized version of a fundamental scalar field), and some hold hope that black holes might be produced that would indicate the existence of higher dimensions. COGENT, Pamela, and others are finding intriguing (and frustratingly contradictory) clues about the true nature of dark matter. And Planck and JWST, if it can overcome its funding and budgetary problems, promise to further refine our view of the cosmos and the role of scalar fields within. Advanced LIGO will be complete in a few years and the future of space-based GW telescopes such as LISA is currently being determined. GW observations will be ground-breaking on so many fronts, but could potentially help distinguish BSs from neutron stars or black holes.
Perhaps future work on boson stars will be experimental, if fundamental scalar fields are observed, or if evidence arises indicating the boson stars uniquely fit galactic dark matter. But regardless of any experimental results found by these remarkable experiments, there will always be regimes unexplored by experiments where boson stars will find a natural home.
Living Rev. Relativity 15, (2012), 6
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