Mimetic Euler-Heisenberg theory, charged solutions and multi-horizon black holes

Nashed, G. G. L.; Nojiri, Shin'ichi

doi:10.48550/arxiv.2107.13550

Cited by 3 publications

(3 citation statements)

References 88 publications

(160 reference statements)

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“…It has also been shown that this theory can explain the flat rotation curves of spiral galaxies without needing to particles DM [10,11]. Mimetic theory of gravity has arisen a lot of enthusiasm in the past few years both from the cosmological viewpoint [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] as well as black holes physics [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50]. The investigations on the mimetic theory of gravity were also generalized to f (R) gravity [51][52][53][54][55][56][57][5...…”

Section: Introductionmentioning

confidence: 99%

Structure formation in mimetic gravity

Farsi¹,

Sheykhi²

2022

Preprint

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Mimetic theory of gravity was proposed as an alternative description for the dark matter (DM) puzzle. It was argued that the mimetic field can encode a dynamical longitudinal degree of freedom which can play the role of mimetic DM. In this paper, we disclose the effects of an extra longitudinal degree of freedom on the evolution of perturbations in the framework of mimetic gravity. We consider a flat Friedmann-Robertson-Walker (FRW) background and explore the linear perturbations by adopting the spherically symmetric collapse formalism. By suitably choosing the potential of the mimetic field, we are able to solve the perturbed field equations in the linear regime and derive the density contrast δm in terms of the redshift parameter z. We observe that δm starts growing from its initial value at the early stages of the universe and as the universe expands, it grows slower compared to the standard cosmology. This may due to the extra degree of freedom of the gravitational field which affects the growth of perturbations. We then consider the effects of this potential on the density abundance and the deceleration parameter. We find out that mimetic potential can play the role of dark energy (DE) and affects the dynamics of matter perturbations and cosmological parameters.

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Section: Introductionmentioning

confidence: 99%

Structure formation in mimetic gravity

Farsi¹,

Sheykhi²

2022

Preprint

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“…A study of the thermodynamics of these black holes was performed in [15,16], while the stability of these black holes, calculating the quasinormal modes, was studied in [17]. Rotating black holes were found in [18,19], while the Euler-Heisenberg theory in modified gravity theories in [20][21][22] was studied and black hole solutions were analyzed.…”

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confidence: 99%

Motion of particles in a magnetically charged Euler-Heisenberg black hole with scalar hair

Theodosopoulos¹,

Karakasis²,

Koutsoumbas³

et al. 2023

Preprint

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We study the geodesic motion of uncharged particles in the background of a magnetically charged Euler-Heisenberg black hole with a scalar hair. The spacetime can be asymptotically (A)dS or flat and we find, analysing the behavior of the effective potential of the radial motion that in all cases there exist stable and unstable orbits. Performing numerical integrations we depict the motion of particles for planetary and critical orbits, as well as for radial geodesics. We discuss the effect that the scalar hair ν, the magnetic charge Qm and the Euler-Heisenberg parameter α have on the particle motion.

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“…Nevertheless, mimetic gravity can be extended in many ways, interpreted as a modification of gravity (for a review see [76]). Since mimetic modified gravity have many interesting applications at the cosmological framework (among them the ability to alleviate the cosmological tensions [77], and to track possible quantum-related defects [78]), an amount of research has been devoted to the investigation of the spherically symmetric solutions too [79][80][81][82][83][84][85][86][87][88][89][90][91][92][93][94][95].…”

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confidence: 99%

New anisotropic star solutions in mimetic gravity

Nashed¹,

Saridakis²

2022

Preprint

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We extract new classes of anisotropic solutions in the framework of mimetic gravity, by applying the Tolman-Finch-Skea metric and a specific anisotropy not directly depending on it, and by matching smoothly the interior anisotropic solution to the Schwarzschild exterior one. Then, in order to provide a transparent picture we use the data from the 4U 1608-52 pulsar. We study the profile of the energy density, as well as the radial and tangential pressures, and we show that they are all positive and decrease towards the center of the star. Furthermore, we investigate the anisotropy parameter and the anisotropic force, that are both increasing functions of the radius, which implies that the latter is repulsive. Additionally, by examining the radial and tangential equation-ofstate parameters, we show that they are monotonically increasing, not corresponding to exotic matter. Concerning the metric potentials we find that they have no singularity, either at the center of the star or at the boundary. Furthermore, we verify that all energy conditions are satisfied, we show that the radial and tangential sound speed squares are positive and sub-luminal, and we find that the surface redshift satisfies the theoretical requirement. Finally, in order to investigate the stability we apply the Tolman-Oppenheimer-Volkoff equation, we perform the adiabatic index analysis, and we examine the static case, showing that in all cases the star is stable.

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Mimetic Euler-Heisenberg theory, charged solutions and multi-horizon black holes

Cited by 3 publications

References 88 publications

Structure formation in mimetic gravity

Structure formation in mimetic gravity

Motion of particles in a magnetically charged Euler-Heisenberg black hole with scalar hair

New anisotropic star solutions in mimetic gravity

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