Bianchi I metric solutions with nonminimally coupled Einstein–Maxwell gravity theory

Ghaffarnejad, Hossein; Gholipour, Hoda

doi:10.1007/s10714-020-02776-x

Cited by 10 publications

(3 citation statements)

References 13 publications

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“…Thus one can infer that stability of the system reaches to a stellar object metric without the horizon which we called it 'electrostatic' stars. In fact this work confirms results of our previous work which recently we showed stability of this metric field via classical perspective [35]. To check that do this mathematical calculations are valid physically?…”

Section: Discussionsupporting

confidence: 90%

Canonical quantization of modified non-gauge invariant Einstein-Maxwell gravity and stability of spherically symmetric electrostatic stars

Ghaffarnejad

2023

Phys. Scr.

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We consider a non-minimally coupled Einstein-Maxwell gravity withno $U(1)$ symmetry property to study stability of an electrostaticstar via canonical quantization approach and obtain that thestability is free of gauge field effects. By calculating theHamiltonian density of the stellar system we show that thecorresponding Wheeler-DeWitt wave functional is similar to asimple harmonic quantum Oscillator for which a non zero ADM massof the system causes a quantization condition on the metricfields. Probability wave packets are described by the Hermitpolynomials. Our mathematical calculations show that in thisapproach of quantum gravity the metric fields are regular for allvalues of the electric potential and so the quantized spacetimehas not both of event and apparent horizons. The most probabilityof the quantized line element is for ground state of the system.To check validation of the model we use Bohr`s correspondenceprincipal and generate directly semi classical approach of thequantized metric states at large quantum numbers where they reachto Schwarzschild like metric according to the Birkhoff's theorem.Also we check that the generated semi classical solutions aresatisfied exact classical metric solutions which are obtained fromEuler Lagrange equations. We show that `charge to mass ratio` ofthe electrostatic star is a constant defined by the couplingconstant of the model and it is in accord to other alternativeapproaches.

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Section: Discussionsupporting

confidence: 90%

Canonical quantization of modified non-gauge invariant Einstein-Maxwell gravity and stability of spherically symmetric electrostatic stars

Ghaffarnejad

2023

Phys. Scr.

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“…Hoffman studied the coupling of the Einstein gravity to BI theory in [5]. Moreover, variety of nonlinear electrodynamics models have been proposed and studied in different frameworks [6] such as special relativity [7], string theory [8,9,10] and notably, in cosmology to explain the cosmic inflation era [11,12] and the accelerated expansion of the late-time universe [13]. The RN black hole as a well-known solution of the EM gravity, is a charged static black hole with mass M and charge Q [14,15].…”

Section: Introductionmentioning

confidence: 99%

Modified gauge invariant Einstein Maxwell gravity and Thermodynamic phase transition of anti de Sitter ReissnerNordstrom black holes

Ghaffarnejad

Ghasemi

2023

Preprint

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By contracting Ricci tensor of metric field with electromagnetic tensor field we make a scalar term added with the Einstein-Maxwell (EM) gravity Lagrangian density and then obtain modified Reissner Nordstrom (RN) black hole metric via perturbation method. In fact our motivation in use of this alternative gravity theory instead of the EM gravity is based on influence of cosmic magnetic field throughout the space time as inevitable effect at duration of cosmic inflation. Our goal in this work is investigation of contribution of this interaction term on the Hawking temperature and possibility of phase transitions too.

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“…Interestingly, in the latter case, an equation was obtained and that resembles the Burgers equation, which describes shock waves moving in a fluid. Latter, a perfect fluid and a charged dust were also considered as a source [11,12].…”

Section: Introductionmentioning

confidence: 99%

On the total energy conservation of the Alcubierre spacetime

Carneiro

Ulhoa

Maluf

et al. 2022

J. Cosmol. Astropart. Phys.

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In this article, we consider the Alcubierre spacetime, such a spacetime describes a “bubble” that propagates with arbitrary global velocity. This setting allows movement at a speed greater than that of light. There are some known problems with this metric, e.g., the source's negative energy and the violation of the source's energy conservation when the bubble accelerates. We address these two issues within the realm of the Teleparallel Equivalent of General Relativity (TEGR). The energy conservation problem can be solved when considering the energy of the gravitational field itself. The total energy of the spacetime, gravitational plus source, is conserved even in accelerated motion. We explicitly show the dependence of energy and gravitational energy flux on the frame of reference, one adapted to a static observer and the other to a free-falling one in the same coordinate system. Addressing the problem of energy negativity of the source, we find that a static observer measures positive energy of the source, while an Eulerian observer measures a negative one. Thus, we surmise that negative energy may be a reference problem.

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Bianchi I metric solutions with nonminimally coupled Einstein–Maxwell gravity theory

Cited by 10 publications

References 13 publications

Canonical quantization of modified non-gauge invariant Einstein-Maxwell gravity and stability of spherically symmetric electrostatic stars

Canonical quantization of modified non-gauge invariant Einstein-Maxwell gravity and stability of spherically symmetric electrostatic stars

Modified gauge invariant Einstein Maxwell gravity and Thermodynamic phase transition of anti de Sitter ReissnerNordstrom black holes

On the total energy conservation of the Alcubierre spacetime

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