Quantum corrections for ABGB black hole

In this paper, we study quantum corrections to the temperature and entropy of a regular Ayón-Beato-García-Bronnikov black hole solution by using tunneling approach beyond semiclassical approximation. We use the first law of black hole thermodynamics as a differential of entropy with two parameters, mass and charge. It is found that the leading order correction to the entropy is of logarithmic form. In the absence of the charge, i.e., e=0, these corrections approximate the corresponding corrections for the Schwarzschild black hole.     

Back reaction and quantum gravity corrections of Hawking radiation from Schwarzschild-de Sitter black hole

Following the Parikh and Wilczek semiclassical tunneling method of massless particle, hawking radiation of Schwarzschild-de Sitter (SdS) black hole have been computed using null geodesic method. Purely thermal and quantum gravity corrections have been made and have shown that both the corrections give the same results and all the tunneling rates are related to change of Bekenstein-Hawking entropy of SdS black hole. The results obtained for SdS black hole are also in accordance with Parikh and Wilczek’s opinion and gives a correction to the Hawking radiation of SdS black hole.     

Fading Hawking radiation

In this study, we explore a particular type Hawking radiation which ends with zero temperature and entropy. The appropriate black holes for this purpose are the linear dilaton black holes. In addition to the black hole choice, a recent formalism in which the Parikh-Wilczek’s tunneling formalism amalgamated with quantum corrections to all orders in ? is considered. The adjustment of the coefficients of the quantum corrections plays a crucial role on this particular Hawking radiation. The obtained tunneling rate indicates that the radiation is not pure thermal anymore, and hence correlations of outgoing quanta are capable of carrying away information encoded within them. Finally, we show in detail that when the linear dilaton black hole completely evaporates through such a particular radiation, entropy of the radiation becomes identical with the entropy of the black hole, which corresponds to “no information loss”.     

Hawking temperature and entropy of Kerr-Sen black hole as a series with dependence on Plank constant

By assumption of a low-energy string theory in addition to the necessity of the semi-classic expansion on action, we study Hawking temperature and entropy of Kerr-Sen black hole. These subjects, recently have introduced in the literature and consist of the new terms of temperature and entropy as the expansion form with powers of ?. Comparing the results with the high energy black hole demonstrates how the semi-classic approximation affects the thermodynamics of the Kerr-Sen black hole, corrected terms classical action and the entropy.     

Entropic gravity resulting from a Yukawa type of correction to the metric for a solar mass black hole

There has been a renewed interest in the recent years in the possibility of deviations from the predictions of Newton’s “inverse-square law” of universal gravitation. One of the reasons for renewing this interest lies in various theoretical attempts to construct a unified elementary particle theory, in which there is a natural prediction of new forces over macroscopic distances. In this paper we study the entropic gravity correction to the gravitational force on the horizon of a black hole whose metric has been modified by a Yukawa term. We find that the gravitational radius of such a black hole is given in-terms of the Lambert function, and the entropic force introduces a extra term that depends on the square of the coupling constant α of the Yukawa potential. In the case alpha equals zero we recover the Newtonian gravitational force on the horizon. In a first effort to obtain a relation between geometry and information, we calculate the Ricci scalar and through entropy we establish a relation to the number of information N where this is given in nats. Finally, we calculate a critical entropy value as well as a critical information number N _c for which the curvature becomes identically zero which implies that the space becomes flat.     

Quantum statistical entropy of Schwarzchild-de Sitter spacetime

Using the quantum statistical method, we calculate quantum statistical entropy between the black hole horizon and the cosmological horizon in Schwarzchild spacetime and derive the expression of quantum statistical entropy in de Sitter spacetime. Under the Unruh-Verlinde temperature of Schwarzchild-de Sitter spacetime in the entropic force views, we obtain the expression of quantum statistical entropy in de Sitter spacetime. It is shown that in de Sitter spacetime quantum statistical entropy is the sum of thermodynamic entropy corresponding black hole horizon and the one corresponding cosmological horizon. And the correction term of de Sitter spacetime entropy is obtained. Therefore, it is confirmed that the black hole entropy is the entropy of quantum field outside the black hole horizon. The entropy of de Sitter spacetime is the entropy of quantum field between the black hole horizon and the cosmological horizon.     

Quasinormal modes of scalar perturbation around a quantum-corrected Schwarzschild black hole

In this paper, we evaluate quasinormal modes (QNMs) of scalar perturbations around a quantum-corrected Schwarzschild black hole by using the third order Wentzel-Kramers-Brillouin (WKB) approximation method. The results show that due to the quantum fluctuations in the background of the Schwarzschild black hole, the QNMs of the black hole damp more slowly when increasing the quantum correction factor (a), and oscillate more slowly.     

Corrected horizon of Kerr-Sen black hole as a series with terms involve powers of the inverse of the area

By means of the semiclassical approximations for the action, the horizon of Kerr-Sen black hole is studied. The corrected entropy of the Kerr-Sen black hole in a low-energy string theory is calculated. By assumption of a flat Friedman-Robertson-Walker (F.R.W.) geometries, we study horizon and present the semi-classic approximation affects of the thermodynamics properties. We discuss some physical consequences of this result and the properties of the Kerr-Sen black hole.     

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.     

A comparison of the entropies of collapsing stars and black holes

We considered three modes of black hole formation: (I) a black hole kernel first forms at the centre of a collapsing star and as the outer matter falls, the kernel grows until the whole star becomes a black hole; (II) all the layers of a collapsing simultaneously satisfy the Schwarzschild condition; (III) the outermost layer first satisfies the Schwarzschild condition. For each mode, we calculated the entropy carried by the collapsing matter, S_m, and the entropy of the black hole so formed, S_BH. We found S_BH to be 10¹⁹ times S_m and the lower limit of the mass capable of becoming a black hole to be the Planck mass, M_p = 10^?5g. A discussion on the nature of S_BH led us to think that S_BH possibly contains things other than the ordinary thermodynamical entropy.     

Change in entropy of non-spinning black holes w.r.t. the radius of event horizon in XRBs

The present research paper discusses the derivation for the change in entropy of Non- spinning black holes with respect to the change in the radius of event horizon applying the first law of black hole mechanics ( $\delta M = \frac{\kappa}{8\pi} \delta A + \varOmega\delta J - \upsilon\delta Q$ ) with the relation for the change in entropy δS=8πMδM. When the work is further extended with proper operation, the entropy of black hole is obtained almost the same as the Bekenstein-Hawking entropy of black hole. This is the entirely new method to obtain the change in entropy of Non-spinning black holes w.r.t. the radius of event horizon and Hawking entropy of black hole. We have also calculated their values for different types of test non-spinning black holes having masses 5–20M _⊙ found in X-ray binaries (Narayan, gr-qc/0506078v1, 2005).     

Shadow of rotating Hořava-Lifshitz black hole

The shadow of rotating Ho?ava-Lifshitz black hole has been studied and it was shown that in addition to the specific angular momentum a, parameters of Ho?ava-Lifshitz spacetime essentially deform the shape of the black hole shadow. For a given value of the black hole spin parameter a, the presence of a parameter Λ _W and KS parameter ω enlarges the shadow and reduces its deformation with respect to the one in the Kerr spacetime. We have found a dependence of radius of the shadow R _s and distortion parameter δ _s from parameter Λ _W and KS parameter ω both. Optical features of the rotating Ho?ava-Lifshitz black hole solutions are treated as emphasizing the rotation of the polarization vector along null congruences. A comparison of the obtained theoretical results on polarization angle with the observational data on Faraday rotation measurements provides the upper limit for the δ parameter as δ≤2.1?10^?3.     

Reversible-process black hole thermodynamics

Bekenstein, Hawking, Gibbons and Perry have discussed the case of placing a Schwarzschild black hole inside an ideal, reflecting box, thereby setting up an equilibrium state. In this paper, we discuss more generally the thennodynamical properties of such a system. Starting from adiabatic expansion of the system, we are naturally led to the definition of total entropy and of black hole entropy. We next point out the two conditions for stable equilibrium between the black hole and the radiation, V < V_E and E_r < M/4 are not equivalent: only the former is necessary and sufficient. Lastly, we examine three quasi-static processes of evaporation of the black hole, expansion at constant energy, energy release at constant volume and adiabatic expansion.     

Basic thermodynamic parameters of a black hole resulting from a Yukawa type of correction to the metric

There has been a renewed interest in the recent years in the possibility of deviations from the predictions of Newton’s “inverse-square law” of universal gravitation. One of the reasons for renewing this interest lies in various theoretical attempts to construct a unified elementary particle theory, in which there is a natural prediction of new forces over macroscopic distances. Therefore the existence of such a force would only coexist with gravity, and in principle could only be detected as a deviation from the inverse square law, or in the “universality of free fall” experiments. New experimental techniques such that of Sagnac interferometry can help explore the range of the Yukawa correction λ≥10¹⁴ m where such forces might be present. It may be, that future space missions might be operating in this range which has been unexplored for very long time. In this paper we derive the basic thermodynamic parameters of such a Yukawa stationary spherically symmetric black hole. First, the expression for the event horizon of such a black hole is derived, with the help of which the temperature, entropy and heat capacity of this particular black hole are obtained. We have also obtained analytical expressions for the change of mass of such black hole, and also its corresponding evaporation time.     

Atomic data and electron-impact broadening effect in DO white dwarf atmospheres: Si vi

Energy levels, electric dipole transition probabilities and oscillator strengths in five times ionized silicon have been calculated in intermediate coupling. The present calculations were carried out with the general purpose atomic structure program superstructure . The relativistic corrections to the non-relativistic Hamiltonian are taken into account through the Breit–Pauli approximation. We have also introduced a semi-empirical correction [term energy corrections (TEC)] for the calculation of the energy levels. These atomic data are used to provide semiclassical electron-, proton- and ionized helium-impact linewidths and shifts for 15 Si  vi multiplet. Calculated results have been used to consider the influence of Stark broadening for DO white dwarf atmospheric conditions.     

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.     

The generalized uncertainty principle and the quantum entropy due to spin fields on the Reissner-Nordström black hole background

By using the null tetrad and the ’t Hooft brick-wall model, the quantum entropies of a Reissner-Nordström black hole due to the Weyl neutrino, electromagnetic, massless Rarita-Schwinger and gravitational fields for the source-free case are investigated from a generalized uncertainty principle. The divergence structure for the entropy is demonstrated. In addition to the usual linearly and logarithmically divergent terms, additional quadratic, cubic, biquadratic and other higher order divergences exist near the event horizon in the entropy, which not only depend on the black hole characteristics but also on the spin fields and the gravitational interactions. The terms describe the contribution of the quantum fields to the entropy and the effects of the generalized uncertainty principle on it. If the smallest length scale is taken into account, the contribution of the gravitational interactions to the entropy is found to be a part of the dominant term and very important, and therefore it can not be neglected.     

Corrections to the Cardy-Verlinde formula at the Planck scale

The possible corrections to the thermodynamic quantities of higher dimensional Schwa-rzschild black hole have been investigated by considering the generalized uncertainty principle (GUP) and the modified dispersion relation (MDR) separately. The quantum gravitational corrections to the Hawking temperature, energy and entropy of the black hole have been calculated based on both the GUP and the MDR analysis. The explicit form of the corrections are worked out up to the sixth power of the Planck length. The impacts of GUP and MDR have been used separately to obtain the quantum gravitational corrections to the Cardy-Verlinde (C-V) formula. It has been shown that the usual C-V entropy formula receives some new corrections. Also the renormalized form of the C-V formula has been introduced by redefining Virasoro operator and central charge within both the GUP and the MDR. Through comparison of the corrections obtained from GUP and MDR approaches it has been found that the results of these two alternative approaches should be identical if one uses the suitable expansion coefficients.     

Power-law and logarithmic entropy-corrected Ricci viscous dark energy and dynamics of scalar fields

In this work, I consider the logarithmic-corrected and the power-law corrected versions of the holographic dark energy (HDE) model in the non-flat FRW universe filled with a viscous Dark Energy (DE) interacting with Dark Matter (DM). I propose to replace the infra-red cut-off with the inverse of the Ricci scalar curvature R. I obtain the equation of state (EoS) parameter ω _Λ , the deceleration parameter q and the evolution of energy density parameter $\varOmega_{D}'$ in the presence of interaction between DE and DM for both corrections. I study the correspondence of the logarithmic entropy corrected Ricci Dark Dnergy (LECRDE) and power-law entropy corrected Ricci Dark Energy (PLECRDE) models with the the Modified Chaplygin Gas (MCG) and some scalar fields including tachyon, K-essence, dilaton and quintessence. I also make comparisons with previous results.     

The Eddington Ratio of H 2 O Maser Host AGN

The Eddington ratio λ was derived for the entire maser host AGN sample, based on the intrinsic X-ray luminosity, the X-ray bolometric correction C _X and the mass of central black hole. Further the [O III] bolometric correction C _{[O III]} was estimated for our sample. Possible relations were also investigated between the maser luminosity and the bolometric luminosity – the Eddington ratio.