Spontaneous scalarization of boson stars

Abstract

We study the spontaneous scalarization of spherically symmetric, asymptotically flat boson stars in the $(\alpha \mathcal{R}+\gamma \mathcal{G}){\varphi }^2$ scalar-tensor gravity model. These compact objects are made of a complex valued scalar field that has harmonic time dependence, while their space-time is static and they can reach densities and masses similar to that of supermassive black holes. We find that boson stars can be scalarized for both signs of the scalar-tensor coupling $\alpha$ and $\gamma$, respectively. This is, in particular, true for boson stars that are {\it a priori} stable with respect to decay into individual bosonic particles. A fundamental difference between the $\alpha$- and $\gamma$-scalarization exists, though: while we find an interval in $\alpha >0$ for which boson stars can {\it never} be scalarized when $\gamma =0$, there is no restriction on $\gamma \ne 0$ when $\alpha =0$. Typically, two branches of solutions exist that differ in the way the boson star gets scalarized: either the scalar field is maximal at the center of the star, or on a shell with finite radius which roughly corresponds to the outer radius of the boson star. We also demonstrate that the former solutions can be radially excited.

10 pages including 5 figures and one table; v2: results on scalar-Gauss-Bonnet model added (including 3 new figures), references added, 15 pages, 8 figures, 1 table

References in corpus (14)

• Spontaneous scalarization of black holes and compact stars from a Gauss-Bonnet coupling
• New Gauss-Bonnet black holes with curvature induced scalarization in the extended scalar-tensor theories
• Evasion of No-Hair Theorems and Novel Black-Hole Solutions in Gauss-Bonnet Theories
• Spontaneous scalarisation of charged black holes
• Black-Hole Solutions with Scalar Hair in Einstein-Scalar-Gauss-Bonnet Theories
• On the stability of scalarized black hole solutions in scalar-Gauss-Bonnet gravity
• Self-interactions and Spontaneous Black Hole Scalarization
• Scalarized black holes in the presence of the coupling to Gauss-Bonnet gravity
• Charged Gauss-Bonnet black holes with curvature induced scalarization in the extended scalar-tensor theories
• Spontaneous scalarization of charged black holes at the approach to extremality
• Black hole scalarisation from the breakdown of scale-invariance
• Wireless Communications and Control for Swarms of Cellular-Connected UAVs
• Hairy black holes, boson stars and non-minimal coupling to curvature invariants
• Trace of the energy-momentum tensor and macroscopic properties of neutron stars

Cited by in corpus (9)

• Large and Ultra-compact Gauss-Bonnet Black Holes with a Self-interacting Scalar Field
• On the Existence of Solutions with a Horizon in Pure Scalar-Gauss-Bonnet Theories
• Dynamical scalarization in Einstein-Maxwell-dilaton theory
• Self-interacting multistate boson stars
• Dynamic generation or removal of a scalar hair
• Scalaroca stars: coupled scalar-Proca solitons
• Boson stars in massless and massive scalar-tensor gravity
• Spontaneous scalarization of self-gravitating magnetic fields
• Dynamical charged black hole spontaneous scalarization in Anti-de Sitter spacetimes