Generalized uncertainty principle and s-wave semiclassical tunneling radiation of Kerr black hole

Based on the generalized uncertainty principle, the modified area and entropy of Kerr black hole is calculated. The semiclassical Parikh-Wilczeck tunneling proposal is applied to a Kerr horizon. It is shown that the tunneling radiation probability of Kerr black hole is modified.     

Semiclassical tunneling radiation of Kehagias-Sfetsos black hole and holographic principle

The thermodynamics of Kehagias-Sfetsos black hole is studied. Applying the generalized second law of thermodynamics, a bound on the semiclassical tunneling radiation of black hole is obtained.     

The generalized uncertainty principle and the thermodynamic quantities near a black hole

The continuous complex Morlet wavelet transform is used to investigate temporal rotation cycle length of daily sunspot areas from May 9, 1874 to February 28, 2010, from a global point of view. The rotation cycle length of the Sun is found to have a secular trend: it decreased from the year of 1874 to 1950s, and since then the Sun is rotating more and more speedily in the long run. The rotation period appears around the maximum times of the Schwabe cycles with statistical significance, but in the minimum times it is always statistically insignificant, although it is found to have no relation with the Schwabe cycle. The period length of the rotation cycle displays the significant periods of 2.61 and 5.77 years.     

Quantum tunneling makes a Reissner–Nordstrom black hole turn into a Kerr–Newman black hole under angular momentum conservation

Hawking radiation can be viewed as a process of particle quantum tunneling near a black hole horizon. When a particle with angular momentum tunnels across the event horizon of a Reissner–Nordstrom black hole, the black hole will change into a Kerr–Newman one. In previous papers, axisymmetric black hole has been studied only when a keeps constant. Changing from Reissner–Nordstrom to Kerr–Newman should be a simple case when a varies. After this, more general radiation including changed a in Kerr or Kerr–Newman spacetimes can be studied in the future. The emission rate of the massless particles with angular momentum is calculated, and the result is consistent with an underlying unitary theory.      

Effect of holographic principle and generalized uncertainty principle on the semiclassical Parikh-Wilczek tunneling radiation of black holes

In the present paper, based on the generalized uncertainty principle, the Parikh-Wilczek black hole tunneling radiation is studied. It is shown that the black hole tunneling radiation receives a correction. Furthermore a bound on the tunneling approach, is shown to be valid when, based on the holographic principle, a bound applied to the black hole entropy.     

The angular momentum of a Kerr black hole

It is pointed out that, when calculating the angular momentum of a Kerr black hole, we should allow for the effect of accretion of scattered electrons in the retrograde direction. By using the radius of smallest circular orbit of the particle as a measure for the capture cross-section by the hole, the calculation is greatly simplified. Thorne's result, a/M = 0.9982, when retrograde photons are considered, is easily obtained. If we allow for retrograde electrons, we get a/M = 0.9986, if we allow for both retrograde electrons and photons, we get a/M = 0.9968; and if we further allow for pair annihilation, we get a/M = 0.9961.     

Hawking radiation and entropy of Kerr-Newman black hole

The entropy correction of Kerr-Newman black hole is investigated using the Hamilton-Jacobi method beyond semiclassical approximation. To get entropy correction, the inverse of the sum of square of event horizon (r ₊) and the square of rotational parameter a of the black hole is taken as the proportionality parameter for quantum corrections of the action I _i to the semiclassical action I ₀. It has been shown that as quantum effects are taken into account the corrections to the Bekenstein-Hawking entropy of the stationary black hole include a logarithmic term and an inverse area term beyond the semiclassical approximation.     

Tortoise coordinate and Hawking effect in a dynamical Kerr black hole

Hawking effect from a dynamical Kerr black hole is investigated using the improved Damour-Ruffini method with a new tortoise coordinate transformation. Hawking temperature of the black hole can be obtained point by point at the event horizon. It is found that Hawking temperatures of different points on the surface are different. Moreover, the temperature does not turn to zero while the dynamical black hole turns to an extreme one.     

Energy accumulating accretion disk orbiting a Kerr black hole

A geometrically thin, energy accumulating $aL-disk is suggested which orbits a Kerr black hole. With increasing internal forces, the “standard” disks develop into energy accumulating disks. These accumulating disks are geometrically thin as long as their internal forces remain below a certain bound, allowing nearly geodesic orbits.     

Entanglement entropy of a black hole and isolated horizon

Using Unruh-Verlinde temperature obtained by entropic force, we directly calculate partition functions of quantum field in Schwarzschild spacetime via quantum statistical method and derive the expression of the black hole statistical entropy. In our calculation the lower limit of integral is the location of isolated horizon introduced in loop quantum gravity and the upper limit of integral is infinity. So the obtained entropy is the statistical entropy from isolated horizon to the infinite. In our calculation there are not the cutoff and approximation. The results showed that, as long as proper Immirzi parameters are selected, the entropy obtained by loop quantum gravity is consistent with the quantum statistical entropy outside the black hole horizon. Therefore the black hole entropy is a quantum entanglement entropy outside the isolated horizon.     

The minimum masses of black holes from the generalized uncertainty principle and the uncertainty principle

In this paper we compare the minimum masses of Schwarzschild black hole obtained from the generalized uncertainty principle and the Heisenberg uncertainty principle. Three minimum masses are obtained. The first two are the order of Planck mass which can be normally accepted. The last one based on Scardigli’s hypothesis and consideration is about M _c ?10¹⁵ g～10²⁰ M _pl which may be problematic. Whether right or wrong, it needs the astronomical observations.     

Extremal black hole entropy satisfying the Nernst theorem

Quantum entropy of extremal black holes has been discussed by many authors. However the contribution of inner event horizon has not been considered. In this paper, we consider the Reissner-Nordström-anti-de Sitter black hole, and show that the contributions lead extremal black hole entropy to obey the Nernst theorem, naturally. Therefore the contributions are important and cannot be neglected in near-extremal and extremal black hole cases.     

Planck absolute entropy of a rotating BTZ black hole

In this paper, the Planck absolute entropy and the Bekenstein–Smarr formula of the rotating Banados–Teitelboim–Zanelli (BTZ) black hole are presented via a complex thermodynamical system contributed by its inner and outer horizons. The redefined entropy approaches zero as the temperature of the rotating BTZ black hole tends to absolute zero, satisfying the Nernst formulation of a black hole. Hence, it can be regarded as the Planck absolute entropy of the rotating BTZ black hole.     

Spacetime dimensionality and logarithmic prefactor in the black hole entropy relation

We study the relation between the existence of the logarithmic prefactor and spacetime dimensionality in black hole entropy relation by a detailed study of a TeV-scale black hole entropy. In a model universe with large extra dimensions and within the Generalized Uncertainty Principle (GUP) framework, we show that probability of black hole production in the Large Hadronic Collider (LHC) decreases for sufficiently large values of the GUP parameter. In this regard, even observation of micro-black holes may be suppressed at TeV energy scale. We determine also the GUP parameter in an extra dimensional scenario by comparing black hole entropy calculated within the GUP and loop quantum gravity frameworks.     

Generalized time-energy uncertainty and temperature of mini black holes

A direct method for calculating the temperature of a hawking particle is carried out. Study of the quantum gravity effects on the hawking radiation is made by imposing a generalized time energy uncertainty principle. It is shown that the Hawking radiation of mini black hole is hotter than the hawking calculations.     

Low-frequency radiation from a particle falling into a Kerr black hole

In this paper we consider the low-frequency limit of the electromagnetic and gravitational radiation from a relativistic particle falling into a Kerr black hole. The radiation spectra are obtained with help of the solution of Teukolsky's equations in terms of the hypergeometric functions. It is shown that in the low-frequency limit the spectra are flat and the power radiated depends strongly on the radiation spin. Dependence of the power on the initial kinetic energy of the radiating particle has the same character as that obtained by the WKB technique for the band of frequencies , where 0=(1–u ₀ ² /c ²)^–1/2 is the particle Lorentz factor at infinity. The full energy radiated is proportional to 0 in 0 for electromagnetic radiation and to ₀ ³ for gravitational radiation.     

Gravitational radiation from a particle falling into a Kerr black hole

The gravitational radiation from a highly relativistic test particle spiralling inward toward a Kerr black hole along a conical surface is estimated. The spectra of several lowest multipoles depending on the polar angle of the falling particle at infinity are obtained for the frequency band c ³ GM^–1.     

High-frequency radiation from a particle falling into a Kerr black hole

The high-frequency electromagnetic and gravitational radiation from a relativistic particle falling into a Kerr and Schwarzschild black hole is considered. The spectral and angular distributions of the radiation power are calculated by the WKB technique to Teukolsky's equations. The spectra obtained have a characteristic exponential cut-off at the frequency = _char. which is proportional to the particle Lorentz factor =(1–v ²/c²)^–1/2. At the frequencies as low as those compared with _char. both electromagnetic and gravitational spectra are flat. The amount of the energy emitted in the low-frequency modes of the radiation depends strongly on the radiation spin. It is proportional to ln for the electromagnetic and to ³ for the gravitational radiation.     

Gravitational wave emission from a companion black hole in the presence of an accretion disc around a super-massive Kerr black hole

Gravitational wave signal characteristics from a binary black hole system in which the companion moves through the accretion disc of the primary are studied. We chose the primary to be a super-massive  ( M = 10⁸ M_⊙)  Kerr black hole and the companion to be a massive black hole  ( M = 10⁵ M_⊙)  to clearly demonstrate the effects. We show that the drag exerted on the companion by the disc is sufficient to reduce the coalescence time of the binary. The drag is primarily due to the fact that the accretion disc on a black hole deviates from a Keplerian disc and becomes sub-Keplerian due to inner boundary condition on the black hole horizon. We consider two types of accretion rates on to the companion. The companion is deeply immersed inside the disc and it can accrete at the Bondi rate which depends on the instantaneous density of the disc. However, an accretion disc can also form around the smaller black hole and it can accrete at its Eddington rate. Thus, this case is also studied and the results are compared. We find that the effect of the disc will be significant in reducing the coalescence time and one needs to incorporate this while interpreting gravitational wave signals emitted from such a binary system.