Rainbow Functions Research Articles

Effect of rainbow function on radial oscillations and some other properties of Chaplygin dark star

Effect of rainbow function on radial oscillations and some other properties of Chaplygin dark star

Effects of gravity rainbow on scalar bosonic and oscillator fields in Bonnor–Melvin space-time with a cosmological constant

In this paper, we explore the relativistic quantum motion of spin-zero scalar charge-free particles influenced by rainbow gravity’s (RG’s) in Bonnor–Melvin magnetic space-time, a four-dimensional solution featuring a positive cosmological constant. We solve the Klein–Gordon equation in this scenario by using two sets of rainbow function: (i) f(χ)=1(1-βχ)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$f(\\chi )=\\frac{1}{(1-\\beta \\,\\chi )}$$\\end{document}, h(χ)=1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$h(\\chi )=1$$\\end{document} and (ii) f(χ)=1(1-βχ)=h(χ)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$f(\\chi )=\\frac{1}{(1-\\beta \\,\\chi )}=h(\\chi )$$\\end{document}, where 0<χ=|E|Ep≤1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$0 < \\chi \\left( =\\frac{|E|}{E_p}\\right) \\le 1$$\\end{document} with Ep\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$E_p$$\\end{document} being the Planck’s energy, E is the particle’s energy, and β\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\beta $$\\end{document} is the rainbow parameter. Furthermore, we study the relativistic quantum oscillator through the Klein–Gordon oscillator equation in the same Bonnor–Melvin magnetic space-time under RG effects. Employing the first pair of rainbow function, we obtain an approximate eigenvalue solution of the quantum oscillator fields. Notably, we demonstrate that the relativistic energy profile of scalar and oscillator particles are influenced by the topology of the geometry and the cosmological constant which is related with the magnetic field strength lies along the symmetry axis. Additionally, we see the impact of rainbow parameter on these approximate relativistic energy profiles in both quantum systems.

Thermodynamic Topology of Topological Black Hole in F(R)-ModMax Gravity’s Rainbow

Abstract In order to include the effect of high energy and topological parameters on black holes in $\mathrm{ F}(R)$ gravity, we consider two corrections to this gravity: energy-dependent spacetime with different topological constants, and a nonlinear electrodynamics field. In other words, we combine $\mathrm{ F}(R)$ gravity’s rainbow with ModMax nonlinear electrodynamics theory to see the effects of high energy and topological parameters on the physics of black holes. For this purpose, we first extract topological black hole solutions in $\mathrm{ F}(R)$-ModMax gravity’s rainbow. Then, by considering black holes as thermodynamic systems, we obtain thermodynamic quantities and check the first law of thermodynamics. The effect of the topological parameter on the Hawking temperature and the total mass of black holes is obvious. We also discuss the thermodynamic topology of topological black holes in $\mathrm{ F}(R)$-ModMax gravity’s rainbow using the off-shell free energy method. In this formalism, black holes are assumed to be equivalent to defects in their thermodynamic spaces. For our analysis, we consider two different types of thermodynamic ensembles. These are: fixed q ensemble and fixed $\phi$ ensemble. We take into account all the different types of curvature hypersurfaces that can be constructed in these black holes. The local and global topology of these black holes are studied by computing the topological charges at the defects in their thermodynamic spaces. Finally, in accordance with their topological charges, we classify the black holes into three topological classes with total winding numbers corresponding to $-1, 0$, and 1. We observe that the topological classes of these black holes are dependent on the value of the rainbow function, the sign of the scalar curvature, and the choice of ensembles.

Maximal acceleration in Rainbow gravity

In this paper, we derive maximal acceleration of a massive particle in Rainbow gravity. Using eight-dimensional phase-space metric compatible with Rainbow gravity, we obtain the maximal acceleration, valid up to first order in the Rainbow gravity parameter η. Using the positivity condition on maximal acceleration, we find that the upper bound on the Rainbow gravity parameter is of the order of for positron and for a black hole. After obtaining the expression for maximal acceleration for different choices of Rainbow functions, we derive corresponding modifications to Unruh temperature. Comparing with the observational value of the Unruh temperature, we find the upper bound on η as for positron radiation. We then derive geodesic equations for different choices of Rainbow functions and also obtain the Newtonian limit of these geodesic equations. We find that the changes in the value of maximum acceleration, maximum temperature and Newtonian force equation are dependent on the choices of Rainbow functions.

The Klein-Gordon equation in the cosmic string and rainbow gravity spacetime under the influence of an external magnetic field and Coulomb potential for PDM particles

Abstract The Klein-Gordon equation in the cosmic string and rainbow gravity spacetime under the influence of an external magnetic field and Coulomb potential for PDM particles is investigated using the NU method. From solution of the Klein-Gordon system with PDM particles, the energy levels are obtained. The energy levels are numerically calculated as a function of rainbow gravity parameters, as a function of magnetic field parameters, as a function of position-dependent mass parameters. We apply some rainbow functions and the results show that the negative and positive energy levels for rainbow function 1 are symmetrical compared to rainbow function 2.

Unraveling the mysteries of wormhole formation in Rastall–Rainbow gravity: a comprehensive study using the embedding approach

The present work looks for the possible existence of static and spherically symmetric wormhole geometries in Rastall–Rainbow gravity. Since, the Rastall–Rainbow gravity model has been constructed with the combination of Rastall theory and the gravity’s rainbow formalism. Taking advantage of the Karmarkar condition for embedding class one metrics, we solve the modified field equations analytically that describe wormholes for specific choice of redshift function. For specific parameter ranges, the solution represents a traversable wormhole that exhibits the violation of null energy condition and consequently the weak energy condition also. Furthermore, we focus on the wormhole stability via adiabatic sound velocity analysis. This model establishes a strong connection between two model parameters, namely, the Rastall parameters and the Rainbow functions, and how it affects the wormhole solution.

KG-particles in a cosmic string rainbow gravity spacetime in mixed magnetic fields

We investigate and report the effects of rainbow gravity on the spectroscopic structure of KG-oscillators in a mixed magnetic field (in the sense that it has the usually described as a uniform and a non-uniform magnetic fields, each at a time) introduced by the 4-vector potential Aμ=(0,0,Aφ,0)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$A_\\mu =(0,0,A_\\varphi ,0)$$\\end{document}, where Aφ=B1r2/2+B2r\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$A_\\varphi =B_1 r^2/2+B_2 r$$\\end{document}, and B1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_1$$\\end{document} and B2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_2$$\\end{document} are magnetic field strengths. We also discuss and report the effects of such a mixed magnetic field on the spectra of KG-oscillators in cosmic string rainbow gravity. In so doing, we introduce a new and quite handy conditionally exact solution associated with the truncation of the biconfluent Heun functions into polynomials. Using a loop quantum gravity motivated rainbow functions, we observe interesting effects when the magnetic field strength B2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_2$$\\end{document} grows up from zero. Such effects include energy levels crossings which, in this case, turns the spectra of the KG-oscillators upside down. Moreover, Landau-like signature on the spectra are observed and discussed. Yet, interestingly, we also observe that rainbow gravity affects the magnetic field as well, in the sense that the magnetic field becomes probe particle energy-dependent one.

Study of scalar particles through the Klein–Gordon equation under rainbow gravity effects in Bonnor–Melvin-Lambda space-time

In our investigation, we explore the quantum dynamics of charge-free scalar particles through the Klein–Gordon equation within the framework of rainbow gravity, considering the Bonnor–Melvin-Lambda (BML) space-time background. The BML solution is characterized by the magnetic field strength along the axis of the symmetry direction which is related to the cosmological constant Λ and the topological parameter α of the geometry. The behavior of charge-free scalar particles described by the Klein–Gordon equation is investigated, utilizing two sets of rainbow functions: (i) f(χ)=(eβχ−1)βχ , h(χ) = 1 and (ii) f(χ) = 1, h(χ)=1+βχ2 . Here 0<χ=∣E∣Ep≤1 with E representing the particle’s energy, E p is the Planck’s energy, and β is the rainbow parameter. We obtain the approximate analytical solutions for the scalar particles and conduct a thorough analysis of the obtained results. Afterwards, we study the quantum dynamics of quantum oscillator fields within this BML space-time, employing the Klein–Gordon oscillator. Here also, we choose the same sets of rainbow functions and obtain the approximate eigenvalue solution for the oscillator fields. Notably, we demonstrate that the relativistic approximate energy profiles of charge-free scalar particles and oscillator fields get influenced by the topology of the geometry and the cosmological constant. Furthermore, we show that the energy profiles of scalar particles receive modifications from the rainbow parameter and the quantum oscillator fields by both the rainbow parameter and the frequency of oscillation.

Effects of rainbow gravity on an electron confined to a triangular well and a periodic potential

We investigate quantum effects concerning the modification of the background via rainbow gravity on an electron. We employ the nonrelativistic approximation of the Dirac equation to analyze these effects in depth. We initially study the interaction between an electron and a uniform electric field, by exploring confinement of the particle to a triangular potential well. We find systematic alterations in the energy levels reliant on the rainbow parameter ϵ. Additionally, we investigate a particle in a periodic potential resembling a ring. We also find consistent alterations in energy levels due to changes in the background via rainbow functions. As in the previously analyzed scenario, the larger the rainbow parameter, the lower the obtained energy levels. These findings underscore a systematic influence of modified gravity on particle dynamics in quantum scenarios.

Energy–Momentum distributions of cylindrical black hole in rainbow gravity

In this study, the energy–momentum localization problem is addressed within the framework of rainbow gravity. Considering the black string black hole, one of the cylindrical black hole models, energy–momentum distributions are obtained for Einstein, Bergmann–Thomson, and Landau–Liftshitz prescriptions in rainbow gravity. All prescriptions’ energy densities are non-zero and depend on the rainbow functions, while the momentum distributions are zero. It has been observed that space-time energy does not depend on the energy of the test particle for some particular choices of rainbow functions. The results obtained for all special cases are given in a table.

Traversable wormholes in Rastall-Rainbow gravity

In this paper, we investigate the existence of asymptotically flat wormhole geometries within the framework of Rastall-Rainbow modified gravity, a synthesis of two distinct theoretical models: Rastall theory and the Rainbow description. Our study uncovers that, when considering specific combinations of free parameters and equations of state, the emergence of static and spherically symmetric wormholes is not feasible within a zero-tidal-force context. By considering the subset of viable solutions, we conduct a rigorous assessment of their stability through adiabatic sound velocity analysis and scrutinize their compliance with the Weak Energy Condition (WEC). Our inquiry provides insights into how the interplay between Rastall parameters and Rainbow functions may alleviate violations of energy conditions in these modified gravity scenarios.

Energy–momentum localization in rainbow gravity

Theoretical physicists generally prefer to modify the general theory of relativity rather than avoiding the successful approaches that have been offered to us. Hence, the rainbow formalism of gravity, which is one of the most studied quantum gravity candidates in literature, has recently gained importance in the field. In this study, the energy–momentum localization problem is discussed for the Taub universe within the framework of rainbow gravity. To achieve this goal, energy and momentum components are calculated by making use of diverse values of rainbow functions in the Einstein, Bergmann–Thomson, Landau–Lifshitz, and the Papapetrou prescriptions for the geometry under consideration. Except for the Landau–Lifshitz prescription, all prescriptions depend on the rainbow functions and the momentum components vanish. Graphical analysis is performed for all the energies obtained. Also, it is shown in limiting condition [Formula: see text] that the results are compatible with the ones obtained in the general relativity.

EXACT SOLUTION OF THE SCHRODINGER EQUATION IN TOPOLOGICALLY MASSIVE SPACETIME

We study exact solutions of the Schr ̈odinger equation in a topologically massive space-time. Exact solutions are obtained in terms of the hypergeometric functions. We also obtained the momentum quantization with the help of the condition of the wave function to be bounded. The investigation is performed in the framework of rainbow formalism of the General Relativity Theory (RGT). The quantized momentum is evaluated for different choices of the rainbow functions.

Massless KG-oscillators in Som-Raychaudhuri cosmic string spacetime in a fine tuned rainbow gravity

A fine tuned rainbow gravity describes both relativistic quantum particles and anti-particles alike. That is, the ratio y=E/EP in the rainbow functions g0(y) and g1(y) should be fine tuned into 0≤y=E/EP≤1⇒y=|E|/EP, otherwise rainbow gravity will only secure Planck's energy scale Ep as the maximal energy for relativistic particles and the anti-particles are left unfortunate (in the sense that their energies will be indefinitely unbounded). Using this fine tuning we discuss the rainbow gravity effect on Klein-Gordon (KG) oscillators in Som-Raychaudhuri cosmic string rainbow gravity spacetime background. We use the rainbow functions: (i) g0(y)=1, g1(y)=1−ϵyn,n=1,2, loop quantum gravity motivated pairs, (ii) g0(y)=g1(y)=(1−ϵy)−1, a horizon problem motivated pair, and (iii) g0(y)=(eϵy−1)/ϵy, g1(y)=1, a gamma-ray bursts motivated pair. We show that the energies obtained using the first two rainbow functions in (i) completely comply with the rainbow gravity model and secure Planck's energy Ep as the maximal energy for both particles and anti-particles. The rainbow function pair in (ii) has no effect on massless KG-oscillators. Whereas, the one in (iii) does not show any eminent tendency towards the Planck's energy as the maximal energy.

Scalar particle creation in a quantum gravity perspective

In gravity’s rainbow perspective (GRP), we intend to analyze the particle production coming from electromagnetic and gravitational fields of the spin-0 (scalar) particles. In accordance with this purpose, a constant external electric field is taken into account together with a rainbow metric with non-isotropic expansion. We obtain the number density of the created Klein–Gordon particles in terms of particle mass, particle charge, external electric field parameter, rainbow functions and particle momentum by using the Bogoliubov transformation method. We display that the number density of the created scalar particles becomes thermal both in the absence of the external constant electric field and in the massless case. We also provide a graphical analysis to scrutinize the particle creation process in the GRP. In this context, it has been observed that rainbow functions drastically alter the number density of the created scalar particles.

Interaction of the DKP particle with the Coulomb-type potential and Aharonov–Bohm potential under the cosmic rainbow gravity

The Duffin–Kemmer–Petiau (DKP) particle with spin 0 interacts with the Aharonov–Bohm (AB) magnetic vector potential and scalar Coulomb-type potential in the cosmic string space–times under the framework of rainbow gravity (RG). By using Bethe–Ansatz method, we obtain the energy eigenvalue and approximate solution to the wave function of the DKP particle with spin 0. We select two sets of rainbow functions and analyze their influence on the energy eigenvalue and wave functions. We find that the energy eigenvalue is determined by the parameters of the rainbow function. It further shows that the rainbow function affects the properties of the space–time where the DKP particle located, and also affects the distribution probability of DKP particles in the space.

Black String Solutions in Rainbow Gravity

In this paper, we studied black string solutions under the consideration of rainbow gravity. We analytically obtained the solution for four-dimensional black strings in terms of the functions f(E/Ep) and g(E/Ep) that sets the energy scale where the rainbow gravity becomes relevant. We also obtained the Hawking temperature for the black string, from which we can see that the rainbow functions play the role of increasing or decreasing the Hawking temperature for a given horizon radius depending on the choice of such rainbow functions. We computed the entropy, specific heat and free energy for the black string. The entropy and specific heat exhibit a rainbow dependence, whereas the free energy is not modified by the rainbow functions. Finally, we studied the effects of rainbow gravity in the orbits of massive and massless particles around a black string. We could verify that neither massive nor massless particles exhibit stable orbits around a black string in the scenario of rainbow gravity for any configuration of rainbow functions.

CLOSED BKS-TYPE UNIVERSES AND DIRAC SPIN EFFECT IN THE RAINBOW GRAVITY

The result related to astrophysical datasets suggest that our universe has recently entered a phase of accelerated expansion. This accelerated expansion is not a situation predicted by the general theory of relativity. Therefore, the emergence of alternative approaches to general relativity has become inevitable. Modifying general relativity and absolute parallelism theory are just two of these theories. In addition, with the discovery of gravitational waves, the need for a view that includes gravitational quantum contributions arose. In this context, rainbow gravity has an approach that also offers quantum contributions to the theory of general relativity and absolute parallelism. In this study, axial vector torsion is calculated for BKS-type universe models using the rainbow gravity formalism. With the calculations made, the vector part and axial vector part components of the torsion tensor are obtained. The spin process, which contributes to the Dirac particles, is also investigated using the rainbow gravitational theory. However, since the obtained axial vector fragment is in time-like form, it is concluded that the spin vector of the Dirac particle is constant. The axial part of the torsion tensor for general BKS-type universe models is calculated and presented in a table for some well-known rainbow functions.

Traversable wormhole models supported by a string cloud in rainbow gravity

The traversable wormholes are fascinating as the shortcuts in space–time. This work discusses the geometry of a traversable wormhole with a string cloud as a source in rainbow gravity. The field equations are developed and solved to obtain the wormhole’s shape function, cloud’s mass density, and string tension. We have calculated the shape function and made it specific to study the dynamics for toy model. Based on the three well-known pairs of rainbow functions (mentioned by Ali and Khalil), the string cloud’s dynamical variables including mass density and string tension are graphically presented. The corresponding energy conditions are also visually depicted. It is found that the source matter (string cloud) of the traversable wormhole must be exotic. However, the positive values of the string tension led to the presence of Casimir and dark energy effects. It is found that the toy model respects the null energy condition for a single pair of rainbow functions, i.e., Rainbow Function Type II. We have concluded that in rainbow gravity theory, the traversable wormhole solutions originating from a string cloud requires the presence of exotic matter to achieve a stable structure.

Thermodynamics of Schwarzschild black hole surrounded by quintessence in gravity's rainbow

According to some quantum gravity models, Lorentz invariance can be violated in the Planck energy scale. With this motivation, we analyze the thermal quantities and the stability of Schwarzschild black hole surrounded by quintessence in gravity's rainbow formalism. To do that, we consider the rainbow functions which are motivated by loop quantum gravity and gamma-ray bursts, and we derive Hawking temperature, specific heat, entropy and the equation of state function. We observe that the presence the quintessence matter field and rainbow gravity affect the stability of the black hole.