No-go theorem for static boson stars

Hod, Shahar

doi:10.1016/j.physletb.2018.01.036

Cited by 11 publications

(16 citation statements)

References 45 publications

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“…For negative coupling α < 0, provided thatφ 2 > 2/|α| the squared sound speed of the tensor perturbations becomes negative, signaling the eventual occurrence of a Laplacian instability. For a detailed derivation of (227) and of (230) within the perturbative approach we recommend Ref. 542.…”

Section: Phantom Barrier Crossing: General Analysismentioning

confidence: 99%

Selected topics in scalar–tensor theories and beyond

Quirós

2019

Int. J. Mod. Phys. D

109

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Scalar fields have played an important role in the development of the fundamental theories of physics as well as in other branches of physics such as gravitation and cosmology. For a long time these escaped detection until 2012 year when the Higgs boson was observed for the first time. Since then alternatives to the general theory of relativity like the Brans-Dicke theory, scalar-tensor theories of gravity and their higher derivative generalizations -collectively known as Horndeski theories -have acquired renewed interest. In the present review we discuss on several selected topics regarding these theories, mainly from the theoretical perspective but with due mention of the observational aspect. Among the topics covered in this review we pay special attention to the following: 1) the asymptotic dynamics of cosmological models based in the Brans-Dicke, scalar-tensor and Horndeski theories, 2) inflationary models, extended quintessence and the Galileons, with emphasis in causality and stability issues, 3) the chameleon and Vainshtein screening mechanisms that may allow the elusive scalar field to evade the tight observational constraints implied by the solar system experiments, 4) the conformal frames conundrum with a brief discussion on the disformal transformations and 5) the role of Weyl symmetry and scale invariance in the gravitation theories. The review is aimed at specialists as well as at non-specialists in the subject, including postgraduate students.

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Section: Phantom Barrier Crossing: General Analysismentioning

confidence: 99%

Selected topics in scalar–tensor theories and beyond

Quirós

2019

Int. J. Mod. Phys. D

109

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“…In contrast, the spherically symmetric boson star solutions [1,2,17,18] cannot be generalized to contain a small Schwarzschild black hole in their inner region. More general, it has been shown that there is no regular static asymptotically flat solution with an event horizon in these models with a complex scalar field, which harmonically depends on time [26,27]. This situation is not unique, however.…”

Section: Introductionmentioning

confidence: 97%

“…These static black holes provide the first known counter-examples to the celebrated no-hair conjecture [22] (see also [23][24][25] for further references and discussion).In contrast, the spherically symmetric boson star solutions [1,2,17,18] cannot be generalized to contain a small Schwarzschild black hole in their inner region. More general, it has been shown that there is no regular static asymptotically flat solution with an event horizon in these models with a complex scalar field, which harmonically depends on time [26,27].…”

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confidence: 99%

Kerr black holes with synchronised scalar hair and boson stars in the Einstein-Friedberg-Lee-Sirlin model

Kunz

Perapechka

Shnir

2019

J. High Energ. Phys.

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We consider the Friedberg-Lee-Sirlin model minimally coupled to Einstein gravity in four spacetime dimensions. The renormalizable Friedberg-Lee-Sirlin model consists of two interacting scalar fields, where the mass of the complex scalar field results from the interaction with the real scalar field which has a finite vacuum expectation value. We here study a new family of self-gravitating axially-symmetric, rotating boson stars in this model. In the flat space limit these boson stars tend to the corresponding Q-balls. Subject to the usual synchronization condition, the model admits spinning hairy black hole solutions with two different types of scalar hair. We here investigate parity-even and parity-odd boson stars and their associated hairy black holes. We explore the domain of existence of the solutions and address some of their physical properties. The solutions exhibit close similarity to the corresponding boson stars and Kerr black holes with synchronised scalar hair in the O(3)-sigma model coupled to Einstein gravity and to the corresponding solutions in the Einstein-Klein-Gordon theory with a complex scalar field, where the latter are recovered in a limit. arXiv:1904.13379v2 [gr-qc] 9 May 2019where the scalar field possesses a harmonic time dependence [1,2].Similar static localized field configurations with finite energy exist in Einstein-Skyrme theory [3][4][5] and in SU(2) Einstein-Yang-Mills theory [6] or Einstein-Yang-Mills-Higgs theory [7][8][9][10]. Certain types of localized gravitating solutions, like boson stars with appropriate interactions, or gravitating monopoles, sphalerons and Skyrmions, are linked to the corresponding flat space solutions, which represent topological solitons/Q-balls [11,12], or monopoles [13,14], sphalerons [15], and Skyrmions [16], respectively.In particular, the Friedberg-Lee-Sirlin model [11] provides an interesting example of a simple renormalizable two-component scalar field theory with natural interaction terms. In this model the complex scalar becomes massive due to the coupling with the real scalar field, since the latter has a finite vacuum expection value generated via a symmetry breaking potential. The Q-ball solutions of this model then appear because of the phase rotation of the complex scalar field, and the coupling to gravity leads to the respective boson stars.Gravitating localized solutions of another type are bound by gravity. Examples are boson stars without appropriate self-interactions [1, 2], or the Bartnik-McKinnon solutions [6]. These do not possess a flat space limit.All these self-gravitating configurations exist for a certain range of values of the parameters of the respective theory, For instance, there are two branches of self-gravitating Skyrmions [4,5], where the lower in energy branch is linked to the flat space Skyrmion in the limit of a vanishing effective gravitational coupling. This lower branch of solutions then ends at some critical maximal value of the gravitational coupling, where it bifurcates with the second, higher in energy branch...

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“…The original Derrick's theorem is limited to the case of flat spacetime and since its publication a number of works have been published considering particular cases, metrics or matter fields (see e.g. [9][10][11][12][13][14][15]). However, no general proof of this theorem in curved spacetime and backreaction has been given.…”

Section: Introductionmentioning

confidence: 99%

Derrick’s theorem in curved spacetime

Carloni

Rosa

2019

Phys. Rev. D

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We extend Derrick's theorem to the case of a generic irrotational curved spacetime adopting a strategy similar to the original proof. We show that a static relativistic star made of real scalar fields is never possible regardless of the geometrical properties of the (static) spacetimes. The generalised theorem offers a tool that can be used to check the stability of localised solutions of a number of types of scalar fields models as well as of compact objects of theories of gravity with a non-minimally coupled scalar degree of freedom.

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No-go theorem for static boson stars

Cited by 11 publications

References 45 publications

Selected topics in scalar–tensor theories and beyond

Selected topics in scalar–tensor theories and beyond

Kerr black holes with synchronised scalar hair and boson stars in the Einstein-Friedberg-Lee-Sirlin model

Derrick’s theorem in curved spacetime

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