Fermions tunneling from Reissner–Nordström black hole

Hawking tunneling radiation of spin ? 1/2 particles from the event horizon of the Reissner–Nordström black hole is studied. We introduce the Dirac equation of the charged particles. We further consider the gravitational interaction and back reaction of the emitted spin particles in the dynamical background space–time. The result shows that when the energy conservation and charge conservation are taken into account, the actual radiation spectrum of fermions also derivates from the thermal one and the tunneling rate is related to the change of Bekenstein–Hawking entropy.     

Gravitational lensing by a black-bounce-Reissner–Nordström spacetime

The European Physical Journal C - According to the optical theorem, the imaginary part of the one-loop radiative shift of the electron energy in an external field (IP1L) determines the total...     

Massive Nordström scalar (density) gravities from universal coupling

Both particle physics and the 1890s Seeliger–Neumann modification of Newtonian gravity suggest considering a “mass term” for gravity, yielding a finite range due to an exponentially decaying Yukawa potential. Unlike Nordström’s “massless” theory, massive scalar gravities are strictly Special Relativistic, being invariant under the Poincaré group but not the conformal group. Geometry is a poor guide to understanding massive scalar gravities: matter sees a conformally flat metric, but gravity also sees the rest of the flat metric, barely, in the mass term. Infinitely many theories exhibit this bimetric ‘geometry,’ all with the total stress–energy’s trace as source. All are new except the Freund–Nambu theory. The smooth massless limit indicates underdetermination of theories by data between massless and massive scalar gravities. The ease of accommodating electrons, protons and other fermions using density-weighted Ogievetsky–Polubarinov spinors in scalar gravity is noted.     

Charged string loops in Reissner–Nordström black hole background

We study the motion of current carrying charged string loops in the Reissner–Nordström black hole background combining the gravitational and electromagnetic field. Introducing new electromagnetic interaction between central charge and charged string loop makes the string loop equations of motion to be non-integrable even in the flat spacetime limit, but it can be governed by an effective potential even in the black hole background. We classify different types of the string loop trajectories using effective potential approach, and we compare the innermost stable string loop positions with loci of the charged particle innermost stable orbits. We examine string loop small oscillations around minima of the string loop effective potential, and we plot radial profiles of the string loop oscillation frequencies for both the radial and vertical modes. We construct charged string loop quasi-periodic oscillations model and we compare it with observed data from microquasars GRO 1655-40, XTE 1550-564, and GRS 1915+105. We also study the acceleration of current carrying string loops along the vertical axis and the string loop ejection from RN black hole neighbourhood, taking also into account the electromagnetic interaction.     

Inner Structure of Entropy of Reissner–Nordström Black Holes

Using the relationship between the entropy and the Euler characteristic, and the usual decomposition of spin connection, an entropy density is introduced to describe the inner structure of the entropy of RN black holes. It is pointed out that the entropy of RN black holes is determined by the singularities of the timelike Killing vector field of RN spacetime, and that these singularities carry the topological numbers, Hopf indices and Brouwer degrees, naturally, which are topological invariants. Taking account of the physical meaning of entropy in statistics, the entropy and its density of RN black holes are modified and they are given by the Hopf indices merely.     

Entropy of Reissner–Nordström–anti-de Sitter Black Hole

By using the method of quantum statistics, we directly derive the partition function of bosonic and fermionic field in Reissner-Nordström-anti-de Sitter black hole and obtain the integral expression of black hole's entropy. It avoids the difficulty in solving the wave equation of various particles. Then via the improved brick-wall method, membrane model, we calculate the statistical entropy of a film with the thickness of (N – 1) around the outside of horizon. In our result we can choose proper parameter in order to let the thickness of film tend to zero and have it approach the surface of horizon. Consequently, the entropy of black hole is proportional to the area of horizon. The stripped term and the divergent logarithmic term in the original brick-wall method no longer exist. In the whole process, physics idea is clear; calculation is simple. We offer a new simple and direct way of calculating the entropy of different complicated black holes.     

Reissner–Nordström thin-shell wormholes with generalized cosmic Chaplygin gas

Following Visser’s approach (Visser in Phys. Rev. D 39:3182, 1989; Nucl. Phys. B 328:203, 1989; Lorentzian wormholes. AIP Press, New York, 1996) of cut and paste, we construct Reissner–Nordström thin-shell wormholes by taking the generalized cosmic Chaplygin gas for the exotic matter located at the wormhole throat. The Darmois–Israel conditions are used to determine the dynamical quantities of the system. The viability of the thin-shell wormholes is explored with respect to radial perturbations preserving the spherical symmetry. We find stable as well as unstable Reissner–Nordström thin-shell wormhole solutions depending upon the model parameters. Finally, we compare our results with both generalized and modified Chaplygin gases.     

Fermions’ Tunnelling from the Reissner- Nordström-Anti-de Sitter Black Hole

Very recent work of Kerner and Mann involving fermions tunnelling from the Rindler space-time and a general non-rotating black hole is extended to the case of Reissner-Nordström-anti-de Sitter black hole. Due to the couple between the gravity field and electromagnetic field, we introduce the Dirac equation of the charged particles to determine the action of the radiation. We further consider the correction of the thermal spectrum in the unfixed background space time. It is shown that when the energy and charge conservations are considered, the tunnelling rate of fermions is also related to the change of Bekenstein-Hawking entropy, implying the underlying unitary theory is satisfied.     

Nordström’s scalar theory of gravity and the equivalence principle

General Relativity obeys the three equivalence principles, the “weak” one (all test bodies fall the same way in a given gravitational field), the “Einstein” one (gravity is locally effaced in a freely falling reference frame) and the “strong” one (the gravitational mass of a system equals its inertial mass to which all forms of energy, including gravitational energy, contribute). The first principle holds because matter is minimally coupled to the metric of a curved spacetime so that test bodies follow geodesics. The second holds because Minkowskian coordinates can be used in the vicinity of any event. The fact that the latter, strong, principle holds is ultimately due to the existence of superpotentials which allow to define the inertial mass of a gravitating system by means of its asymptotic gravitational field, that is, in terms of its gravitational mass. Nordström’s theory of gravity, which describes gravity by a scalar field in flat spacetime, is observationally ruled out. It is however the only theory of gravity with General Relativity to obey the strong equivalence principle. I show in this paper that this remarkable property is true beyond post-newtonian level and can be related to the existence of a “Nordström-Katz” superpotential.     

Nordström,Ehrenfest, and the Role of Dimensionality in Physics

In the summer of 1916, Finnish physicist Gunnar Nordström (1881–1923) arrived in Leiden to carry out research with Paul Ehrenfest (1880–1933), Hendrik A. Lorentzs successor in the chair of theoretical physics. Nordström had recently published the first five-dimensional unified model of the universe, a theory that went virtually unnoticed by the physics community. Ehrenfests personal journals reveal that Nordströms visit coincided with a flowering of Ehrenfests own interest in dimensionality, which resulted in his well-known paper on the connection between the fundamental laws of physics and the three-dimensionality of space. I examine Nordströms and Ehrenfests collaboration and explore the relationship between their ideas and the Kaluza-Klein model of five-dimensional unification.Paul Halpern is Professor of Physics at the University of the Sciences in Philadelphia. He received a Guggenheim Fellowship in 2002 to study the history of dimensionality in science.     

Dynamics of a thin shell in the Reissner—Nordström metric

The dynamics of a thin spherically symmetric gravitating shell around an electrically charged Reissner—Nordström black hole is considered. The energy—momentum tensor of an electrically neutral shell is modeled by an ideal fluid with a polytropic equation of state. The dynamics of a shell with a dust equation of state can be traced completely analytically. The Carter—Penrose diagrams that describe the global geometry and all possible types of motions of a gravitating shell in the case of an eternal black hole have been constructed.The conditions have been found under which stable oscillatory motions of the shell take place. These transfer it successively from one universe to the next in an infinite series of identical universes. Such stable oscillatory shell motions are shown to be possible for an arbitrary polytropic equation of state of the shell.     

Quintessence Reissner Nordström Anti de Sitter Black Holes and Joule Thomson Effect

In this work we investigate corrections of the quintessence regime of the dark energy on the Joule-Thomson (JT) effect of the Reissner Nordström anti de Sitter (RNAdS) black hole. The quintessence dark energy has equation of state as p _q = ωρ _q in which \(-1<\omega <-\frac {1}{3}\). Our calculations are restricted to ansatz: ω = ??1 (the cosmological constant regime) and \(\omega =-\frac {2}{3}\) (quintessence dark energy). To study the JT expansion of the AdS gas under the constant black hole mass, we calculate inversion temperature T _i of the quintessence RNAdS black hole where its cooling phase is changed to heating phase at a particular (inverse) pressure P _i . Position of the inverse point {T _i , P _i } is determined by crossing the inverse curves with the corresponding Gibbons-Hawking temperature on the T-P plan. We determine position of the inverse point versus different numerical values of the mass M and the charge Q of the quintessence AdS RN black hole. The cooling-heating phase transition (JT effect) is happened for M > Q in which the causal singularity is still covered by the horizon. Our calculations show sensitivity of the inverse point {T _i , P _i } position on the T-P plan to existence of the quintessence dark energy just for large numerical values of the AdS RN black holes charge Q. In other words the quintessence dark energy dose not affect on position of the inverse point when the AdS RN black hole takes on small charges.     

Spectroscopy of a Reissner–Nordström black hole via an action variable

With the help of the Bohr–Sommerfeld quantization rule, the area spectrum of a charged, spherically symmetric spacetime is obtained by studying an adiabatic invariant action variable. The period of the Einstein–Maxwell system, which is related to the surface gravity of a given spacetime, is determined by Kruskal-like coordinates. It is shown that the area spectrum of the Reissner–Nordström black hole is evenly spaced and the spacing is the same as that of a Schwarzschild black hole, which indicates that the area spectrum of a black hole is independent of its parameters. In contrast to quasi-normal mode analysis, we do not impose the small charge limit, as the general area gap 8π is obtained.     

Hawking radiation of a Reissner–Nordström–de Sitter black hole

Generalizing the method proposed by Damour–Ruffini, we discuss Hawking radiation of a Reissner–Nordström–de Sitter (RNdS) black hole. Under the condition that total energy and charge are conserved, taking the reaction of the radiation of particles to the spacetime into consideration and considering the interrelation between the event horizon and cosmological horizon, we investigate radiation spectrum of RNdS spacetime by a new Tortoise coordinate transformation. This radiation spectrum is no longer a purely thermal spectrum. It is related to the changes in the Bekenstein–Hawking entropy corresponding the event horizon and cosmological horizon. The result satisfies the unitary principle.     

Ortho- and Para-helium in Relativistic Schrödinger Theory

The characteristic features of ortho- and para-helium are investigated within the framework of Relativistic Schr?dinger Theory (RST). The emphasis lies on the conceptual level, where the geometric and physical properties of both RST field configurations are inspected in detail. From the geometric point of view, the striking feature consists in the splitting of the -valued bundle connection into an abelian electromagnetic part (organizing the electromagnetic interactions between the two electrons) and an exchange part, which is responsible for their exchange interactions. The electromagnetic interactions are mediated by the usual four-potentials A _μ and thus are essentially the same for both types of field configurations, where naturally the electrostatic forces (described by the time component A ₀ of A _μ) dominate their magnetostatic counterparts (described by the space part A of A _μ). Quite analogously to this, the exchange forces are as well described in terms of a certain vector potential (B _μ), again along the gauge principles of minimal coupling, so that also the exchange forces split up into an “electric” type ( ) and a “magnetic” type ( ). The physical difference of ortho- and para-helium is now that the first (ortho-) type is governed mainly by the “electric” kind of exchange forces and therefore is subject to a stronger influence of the exchange phenomenon; whereas the second (para-) type has vanishing “electric” exchange potential (B ₀ ≡ 0) and therefore realizes exclusively the “magnetic” kind of interactions ( ), which, however, in general are smaller than their “electric” counterparts. The corresponding ortho/para splitting of the helium energy levels is inspected merely in the lowest order of approximation, where it coincides with the Hartree–Fock (HF) approximation. Thus RST may be conceived as a relativistic generalization of the HF approach where the fluid-dynamic character of RST implies many similarities with the density functional theory.