Tensor mass and particle number peak at the same location in the scalar-tensor gravity boson star models - an analytical proof

Yazadjiev, Stoytcho S.

doi:10.1088/0264-9381/16/10/102

Cited by 13 publications

(15 citation statements)

References 14 publications

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“…with µ being the red-shifted chemical potential of the baryons. This relation can be derived using a procedure similar to those described in [12] and [16]. With the ralation (20) in mind we can conclude that the loci where the stability changes are lines in the (ψ c ,ρ c ) plane.…”

Section: A Theory Withmentioning

confidence: 99%

Mixed configurations of tensor-multiscalar solitons and neutron stars

Doneva

Yazadjiev

2020

Phys. Rev. D

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In the present paper we consider special classes of massive tensor-multi-scalar theories of gravity whose target space metric admits Killing field(s) with a periodic flow. For such tensor-multi-scalar theories we show that there exist mixed configurations of tenor-multiscalar solitons and relativistic (neutron) stars. The influence of the curvature of the target space on the structure of the mixed configurations is studied for two explicit scalar-tensor theories. The stability of the obtained compact objects is examined and it turns out that the stability region spans to larger central energy densities and central values of the scalar field compared to the pure neutron stars or the pure tensor-multi-scalar solitons. * Electronic address: daniela.doneva@uni-tuebingen.de † Electronic address: yazad@phys.uni-sofia.bg arXiv:1909.00473v1 [gr-qc] 1 Sep 2019

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Section: A Theory Withmentioning

confidence: 99%

Mixed configurations of tensor-multiscalar solitons and neutron stars

Doneva

Yazadjiev

2020

Phys. Rev. D

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“…In contrast with general relativity, the definition of mass in scalar-tensor theories of gravity is in general quite subtle because scalartensor theories violate in general the strong equivalence principle. This results in the appearance of different possible masses as a measure of the total energy of the star [43][44][45][46][47]. It turns out that only the so-called "tensor" mass has natural energy-like properties; for example the tensor mass is positive definite, it decreases monotonically by the emission of gravitational waves and it is well defined even for dynamical spacetimes [43][44][45].…”

Section: Basic Equationsmentioning

confidence: 99%

“…It turns out that only the so-called "tensor" mass has natural energy-like properties; for example the tensor mass is positive definite, it decreases monotonically by the emission of gravitational waves and it is well defined even for dynamical spacetimes [43][44][45]. Moreover, it is the tensor mass that leads to a physically acceptable picture in the theory of the stars -the tensor mass peaks at the same point as the particle number, which is a crucial property for the stability of the static stars [46,47]. Therefore, it is the tensor mass that should be taken as the physical mass 3 .…”

Section: Basic Equationsmentioning

confidence: 99%

Rapidly rotating neutron stars in scalar-tensor theories of gravity

et al. 2013

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We perform the first study of the oscillation frequencies of rapidly rotating neutron stars in alternative theories of gravity, focusing mainly on the fundamental f-modes. We concentrated on a particular class of alternative theories-the (massive) scalar-tensor theories. The generalization to rapid rotation is important because on one hand the rapid rotation can magnify the deviations from general relativity compared to the static case and on the other hand some of the most efficient emitters of gravitational radiation, such as the binary neutron star merger remnants, are supposed to be rotating close to their Kepler (mass-shedding) limits shortly after their formation. We have constructed several sequences of models starting from the nonrotating case and reaching up to the Kepler limit, with different values of the scalar-tensor theory coupling constant and the scalar field mass. The results show that the deviations from pure Einstein's theory can be significant especially in the case of nonzero scalar field mass. An important property of the oscillation modes of rapidly rotating stars is that they can become secularly unstable due to the emission of gravitational radiation, that is so-called Chandrasekhar-Friedman-Schutz instability. Such unstable modes are efficient emitters of gravitational radiation. Our studies show that the inclusion of nonzero scalar field would decrease the threshold value of the normalized angular momentum where this instability stars to operate, but the growth time of the instability seems to be increased compared to pure general relativity.

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“…For the Jordan frame, the proper mass in the FL of thermodynamics is the ADM mass in the Einstein frame M. Similarly, for boson and fermion stars the proper measure for the energy of the system is again the ADM mass in the Einstein frame M. For more details on the subject we would refer the reader to the works [47,48,49,50].…”

Section: Thermodynamicsmentioning

confidence: 99%

Phases of 4d Scalar–tensor Black Holes Coupled to Born–infeld Nonlinear Electrodynamics

2008

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Recent results show that when non-linear electrodynamics is considered the no-scalar-hair theorems in the scalar-tensor theories (STT) of gravity, which are valid for the cases of neutral black holes and charged black holes in the Maxwell electrodynamics, can be circumvented [1,2]. What is even more, in the present work, we find new non-unique, numerical solutions describing charged black holes coupled to non-linear electrodynamics in a special class of scalar-tensor theories. One of the phases has a trivial scalar field and coincides with the corresponding solution in General Relativity. The other phases that we find are characterized by the value of the scalar field charge. The causal structure and some aspects of the stability of the solutions have also been studied. For the scalar-tensor theories considered, the black holes have a single, non-degenerate horizon, i.e., their causal structure resembles that of the Schwarzschild black hole. The thermodynamic analysis of the stability of the solutions indicates that a phase transition may occur.

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Tensor mass and particle number peak at the same location in the scalar-tensor gravity boson star models - an analytical proof

Cited by 13 publications

References 14 publications

Mixed configurations of tensor-multiscalar solitons and neutron stars

Mixed configurations of tensor-multiscalar solitons and neutron stars

Rapidly rotating neutron stars in scalar-tensor theories of gravity

Phases of 4d Scalar–tensor Black Holes Coupled to Born–infeld Nonlinear Electrodynamics

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