Boson stars in a theory of complex scalar fields coupled to the U (1) gauge field and gravity

2015

Gen Relativ Gravit

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We study boson stars in a theory of complex scalar field coupled to Einstein gravity with the potential: V (|Φ|) := m 2 |Φ| 2 + 2λ |Φ| (where m 2 and λ are positive constant parameters). This could be considered either as a theory of massive complex scalar field coupled to gravity in a conical potential or as a theory in the presence of a potential which is an overlap of a parabolic and a conical potential. We study our theory with positive as well as negative values of the cosmological constant Λ . Boson stars are found to come in two types, having either ball-like or shell-like charge density. We have studied the properties of these solutions and have also determined their domains of existence for some specific values of the parameters of the theory. Similar solutions have also been obtained by Hartmann, Kleihaus, Kunz, and Schaffer, in a V-shaped scalar potential.Keywords Gravity Theories · Boson stars · Boson shells · Q-balls · Q-shells A study of boson shells and boson stars in scalar electrodynamics with a self-interacting complex scalar field Φ coupled to Einstein gravity is of a very wide interest in the gravity theories[1]- [26] . Hartmann, Kleihaus, Kunz, and Schaffer (HKKS) [2,3] have recently studied boson stars in a theory of complex scalar field coupled to Einstein gravity in a V-shaped scalar potential: V (ΦΦ * ) ≡ V (|Φ|) = λ c |Φ| (where λ c is a constant). They have found that the boson stars come in two types, having either ball-like or shell-like charge density. They have studied the properties of these solutions and have also determined their domains of existence.Actually, the boson stars represent localized self-gravitating solutions [6,7,8], that have been considered in many different contexts [9,10,11,12,13]. To obtain boson stars, typically a complex scalar field Φ is considered. The U(1) invariance of the theory then provides a conserved Noether current.The properties of the boson stars depend strongly on the self-interaction employed. In particular, as discussed by Lee and collaborators [14] and by Coleman [15], the existence of a flat space-time limit of these localized solutions, i.e., the existence of Q-balls, puts constraints on the types of self-interaction possible.Arodz and Liz showed, that besides Q-balls another type of localized solution could also arise in flat space, when a V-shaped self-interaction is employed in the presence of a gauge field [16,17,18]. In this type of solution, the energy density is no longer ball-like as in the case of Q-balls, but it is instead shell-like.

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confidence: 92%

Boson stars in a theory of complex scalar field coupled to gravity

2015

Gen Relativ Gravit

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“…Studies of the charged compact boson stars in a theory involving a massive complex scalar field with a conical potential coupled to a U(1) gauge field and gravity were undertaken in Refs. [31,32] and [33,34]. In this work, the 2D and 3D phase diagrams were investigated in rather great detail, and multiple bifurcation points showing the presence of rather rich physics were obtained for a particular range of the parameters of the theory.…”

Section: Introductionmentioning

confidence: 99%

“…In this work, the 2D and 3D phase diagrams were investigated in rather great detail, and multiple bifurcation points showing the presence of rather rich physics were obtained for a particular range of the parameters of the theory. These studies were undertaken in the absence [31,32] as well as in the presence [33,34] of a cosmological constant in the theory.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Phase diagrams of charged compact boson stars

et al. 2019

Eur. Phys. J. C

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Compact boson stars, whose scalar field vanishes identically in the exterior region, arise in a theory involving a massless complex scalar field with a conical potential, when coupled to gravity. Their charged compact generalizations, obtained in the presence of a U(1) gauge field, exhibit further interesting features. On the one hand, charged compact boson shells can arise, whose scalar field vanishes also in the central region, while on the other hand, the domain of existence of charged compact boson stars exhibits bifurcation points. First 2D phase diagrams have been studied before. Here we extend these earlier studies to a larger range of the variables and study additional phase diagrams. We then extend these studies to obtain 3D phase diagrams and present these with a detailed discussion of their various regions with respect to the bifurcation points and argue, that there is an infinite series of such bifurcation points. Thus the theory is seen to contain rich physics in a particular domain of the phase diagrams. We also discuss the dependence of the fields on the dimensionless radial coordinate for some representative points of the phase trajectories in the phase diagrams of the theory.

“…We have calibrated our numerical techniques by reproducing the work of Refs. [1,2] and [14,15,16,17].…”

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confidence: 99%

Some new results on charged compact boson stars

et al. 2017

Physics Letters B

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In this work we present some new results obtained in a study of the phase diagram of charged compact boson stars in a theory involving a complex scalar field with a conical potential coupled to a U(1) gauge field and gravity. We here obtain new bifurcation points in this model. We present a detailed discussion of the various regions of the phase diagram with respect to the bifurcation points. The theory is seen to contain rich physics in a particular domain of the phase diagram.