Dynamical boson stars

Abstract

The idea of stable, localized bundles of energy has strong appeal as a model for particles. In the 1950s, John Wheeler envisioned such bundles as smooth configurations of electromagnetic energy that he called geons, but none were found. Instead, particle-like solutions were found in the late 1960s with the addition of a scalar field, and these were given the name boson stars. Since then, boson stars find use in a wide variety of models as sources of dark matter, as black hole mimickers, in simple models of binary systems, and as a tool in finding black holes in higher dimensions with only a single Killing vector. We discuss important varieties of boson stars, their dynamic properties, and some of their uses, concentrating on recent efforts.

Total light bending in non-asymptotically flat black hole spacetimes

“…From this, one can deduce the expression for the light geodesic curvature κg in a stationary spacetime (see e.g. equation (13) in [59]).…”

“…A similar effect, but in the strong gravity regime (beyond the weak field limit), is the strong lensing effect, which provides an experimental test for compact astrophysical objects, such as black holes, e.g. the one embedded in M87 galaxy [10] and SgrA* [11], or exotic ultracompact objects like boson stars [12,13], ℓ-boson stars [14][15][16][17], Horndeski stars [18,19], or other exotic compact objects such as superspinars, anisotropic stars, etc (see for example table 1 in [20]).…”

“…For more complex metrics, the tetrad approach offers an alternative way to determine the angular radius of a shadow. For additional details regarding the tetrad approach, see[77,90] 13. This is necessary to guarantee a viable cosmological evolution.…”

Too small to fail: characterizing sub-solar mass black hole mergers with gravitational waves

“…This first question has previously been studied for astrophysical, super-solar mass black holes in next-generation detectors [58, for example] as well as sub-solar mass neutron stars [59]. Given a gravitational wave signal from the coalescence of compact objects, the identification of a sub-solar mass black hole could be complicated by "mimickers" such as sub-solar mass neutron stars or boson stars [60]. While such objects themselves would be astrophysically exotic [61][62][63] and potentially sourced from dark matter [64], it is not yet clear how well current methods of gravitational-wave data analysis will distinguish between sub-solar mass black holes and these alternatives.…”

Bayesian analysis for rotational curves with ℓ-boson stars as a dark matter component

“…Soon after, Ruffini and Bonazzola presented them as static spherically symmetric self-gravitating configurations of quantum spin-zero particles in quantum field theory using the semiclassical gravity approximation [24]. For a general overview about boson stars we recommend [25,26]. Ruffini and Bonazzola's solutions coincide with the classical configurations if all particles populate a specific energy state however, the semiclassical approximation unveil more sophisticated stars.…”