Chains of boson stars

Abstract

We study axially symmetric multisoliton solutions of a complex scalar field theory with a sextic potential, minimally coupled to Einstein's gravity. These solutions carry no angular momentum and can be classified by the number of nodes of the scalar field, k z , along the symmetry axis; they are interpreted as chains with k z þ 1 boson stars, bound by gravity, but kept apart by repulsive scalar interactions. Chains with an odd number of constituents show a spiraling behavior for their Arnowitt-Deser-Misner (ADM) mass (and Noether charge) in terms of their angular frequency, similarly to a single fundamental boson star, as long as the gravitational coupling is small; for larger coupling, however, the inner part of the spiral is replaced by a merging with the fundamental branch of radially excited spherical boson stars. Chains with an even number of constituents exhibit a truncated spiral pattern, with only two or three branches, ending at a limiting solution with finite values of ADM mass and Noether charge.

Asymptotically Flat, Spherical, Self-Interacting Scalar, Dirac and Proca Stars

“…Indeed, even flat space spinning solitons with spin s = 1/2, 1 are yet unreported in the literature. Moreover, even in the static case, new families of non-spherically symmetric solitons should exist, generalizing for a self-interacting potential (and possibly for a higher spin) the s = 0 multipolar boson stars recently reported in [48].…”

Multicenter solutions in Eddington-inspired Born–Infeld gravity

“…When s = +1, we find that as R → R c the Ricci scalar goes like ∼ 1/(R − R c ) 2 and the Kretschmann as ∼ 1/(R − R c ) 4 , having a softer behavior if R c = m, where they become (2m) −1 /(R − R c ) and (2m) −2 /(R − R c ) 2 , respectively. If s = −1, we find that as R → R c the Ricci scalar goes like ∼ 1/(R − R c ) 3 and the Kretschmann as ∼ 1/(R − R c ) 6 , having also a softer behavior if R c = m, where they become − 3 2 (2m) −1 /(R − R c ) and 9 4 (2m) −2 /(R − R c ) 2 , respectively. Since this s = −1 case represents a wormhole, with its throat at R = R c , it is also relevant to look at the curvature scalars in the limit R → 0, where the area of the two-spheres goes to infinity again.…”

“…2 For recent discussions on the interpretation of projective transformations in metric-affine gravities see [44,46,47]. 3 From now on tildes over quantities will indicate those variables defined in the GR frame; in particular this implies that indices are raised and lowered with the q μν metric. Conversely, when the tildes are dropped it will mean that indices are raised and lowered with the g μν metric instead.…”

“…Among the many exact solutions of interest known within general relativity (GR), we find the class of gravitating configurations in self-equilibrium. Such is the case, for instance, of geons [1], gravitating solitons [2,3] and skyrmions [4,5], and other long-lived configurations [6]. There is a sub-class of solutions of such a family corresponding to those where the attractive gravitational field of a system of particles is exactly balanced by a repulsive electrostatic force.…”

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