Lifetime Of Black Hole Research Articles

Relativistic life time of spinning black holes

The present research paper discusses the relativistic study of the life time of black holes using the model Γ=2.098(MM⊙)3×1067 years as proposed by Stephen Hawking and concludes that the relativistic life time of spinning black holes is dependent of mass as well as spinning velocity of black holes.

Black holes in dRGT massive gravity with the signature of EHT observations of M87*

The recent Event Horizon Telescope (EHT) observations of the M87* have led to a surge of interest in studying the shadow of black holes. Besides, investigation of time evolution and lifetime of black holes helps us to veto/restrict some theoretical models in gravitating systems. Motivated by such exciting properties, we study optical features of black holes, such as the shadow geometrical shape and the energy emission rate in modified gravity. We consider a charged AdS black hole in dRGT massive gravity and look for criteria to restrict the free parameters of the theory. The main goal of this paper is to compare the shadow of the mentioned black hole in a rotating case with the EHT data to obtain the allowed regions of the model parameters. Therefore, we employ the Newman-Janis algorithm to build the rotating counterpart of static solution in dRGT massive gravity. We also calculate the energy emission rate for the rotating case and discuss how the rotation factor and other parameters affect the emission of particles around the black holes.

The spectrum of Hawking radiation in Tsallis statistical mechanics

Hawking radiation is one of the cores in modern gravitational theory. Several articles have calculated the spectrum of Hawking radiation in Boltzmann–Gibbs statistical mechanics. However, based on recent researches, gravitational systems cannot be studied by the standard statistical mechanics. In this article, we calculate the modification to the spectrum of Hawking radiation in Tsallis statistical mechanics. We obtain the modified Stefan–Boltzmann’s law and modified power of Hawking radiation. We confirm the conclusion proposed by Giddings, namely, the radiation should originate from the effective radius, which extends well outside the horizon of black-hole. The lifetime of black hole and the effect of large q are discussed as well.

Model metrics for quantum black hole evolution: Gravitational collapse, singularity resolution, and transient horizons

It is widely accepted that curvature singularity resolution should be a feature of quantum gravity. We present a class of time-dependent asymptotically flat spherically symmetric metrics that model gravitational collapse in quantum gravity. The metrics capture intuitions associated with the dynamics of singularity resolution, and horizon formation and evaporation following a matter bounce. A parameter in the metric associated with the speed of the bounce determines black hole lifetime as a power of its mass; this includes the Hawking evaporation time $M^{3}$.

Fate of quantum black holes

We study the quantum dynamics of the Lema\^{\i}tre-Tolman-Bondi space-times using a polymer quantization prescription based on loop quantum cosmology that incorporates fundamental discreteness. By solving an effective equation derived from this quantization, we find analytical solutions for the Oppenheimer-Snyder and thin-shell collapse models, and numerical solutions for a variety of asymptotically flat collapsing dust profiles. Our study (i) tracks the formation, evolution, and disappearance of dynamical horizons, (ii) shows that matter undergoes a nonsingular bounce that results in an outgoing shock wave, (iii) determines black hole lifetime to be proportional to the square of its mass, and (iv) provides a conformal diagram that substantially modifies the standard ``information loss'' picture by resolving the singularity and replacing the event horizon by transient apparent horizons.

Steady critical accretion onto black holes: Self-gravity and sonic point characteristics

The spherically symmetric steady accretion of polytropic perfect fluids onto a black hole is the simplest flow model that can demonstrate effects of backreaction (selfgravity). It has been discovered 16 years ago that backreaction does not influence some ("intensive") characteristics of sonic points, under suitable conditions. Herein we consider a wider class of equations of state, with polytropic indices in the range (1,2], and establish detailed boundary conditions that allow one to prove this fact. We find also numerical examples showing limits of our analytic criteria - if suitable analytic conditions are not satisfied, then selfgravity influences all characteristics of sonic points. That fact constrains the applicability of the recent proposal of Baumgarte and Shapiro to estimate the lifetime of black holes within compact stellar objects.

Quantum Gravity of Dust Collapse: Shock Waves from Black Holes.

We study the quantum gravitational collapse of spherically symmetric pressureless dust. Using an effective equation derived from a polymer quantization in the connection-triad phase space variables of general relativity, we find numerically, for a variety of initial dust configurations, that (i)trapped surfaces form and disappear as an initially collapsing density profile evolves into an outgoing shock wave; (ii)black hole lifetime is proportional to the square of its mass; and (iii)there is no mass inflation at inner apparent horizons. These results provide a substantially different view of black hole formation and subsequent evolution than found from semiclassical analyses.

Primordial black hole evaporation and dark matter production. I. Solely Hawking radiation

Hawking evaporation of black holes in the early Universe is expected to copiously produce all kinds of particles, regardless of their charges under the Standard Model gauge group. For this reason, any fundamental particle, known or otherwise, could be produced during the black hole lifetime. This certainly includes dark matter (DM) particles. This paper improves upon previous calculations of DM production from primordial black holes (PBH) by consistently including the greybody factors, and by meticulously tracking a system of coupled Boltzmann equations. We show that the initial PBH densities required to produce the observed relic abundance depend strongly on the DM spin, varying in about $\sim 2$ orders of magnitude between a spin-2 and a scalar DM in the case of non-rotating PBHs. For Kerr PBHs, we have found that the expected enhancement in the production of bosons reduces the initial fraction needed to explain the measurements. We further consider indirect production of DM by assuming the existence of additional and unstable degrees of freedom emitted by the evaporation, which later decay into the DM. For a minimal setup where there is only one heavy particle, we find that the final relic abundance can be increased by at most a factor of $\sim 4$ for a scalar heavy state and a Schwarzschild PBH, or by a factor of $\sim 4.3$ for a spin-2 particle in the case of a Kerr PBH.

Hawking evaporation of Einstein\u2013Gauss\u2013Bonnet AdS black holes in Dgeqslant 4 dimensions

Einstein–Gauss–Bonnet theory is a string-generated gravity theory when approaching the low energy limit. By introducing the higher order curvature terms, this theory is supposed to help to solve the black hole singularity problem. In this work, we investigate the evaporation of the static spherically symmetric neutral AdS black holes in Einstein–Gauss–Bonnet gravity in various spacetime dimensions with both positive and negative coupling constant alpha . By summarizing the asymptotic behavior of the evaporation process, we find the lifetime of the black holes is dimensional dependent. For alpha >0, in Dgeqslant 6 cases, the black holes will be completely evaporated in a finite time, which resembles the Schwarzschild-AdS case in Einstein gravity. While in D=4,5 cases, the black hole lifetime is always infinite, which means the black hole becomes a remnant in the late time. Remarkably, the cases of alpha >0, D=4,5 will solve the terminal temperature divergent problem of the Schwarzschild-AdS case. For alpha <0, in all dimensions, the black hole will always spend a finite time to a minimal mass corresponding to the smallest horizon radius r_{min}=sqrt{2|alpha |} which coincide with an additional singularity. This implies that there may exist constraint conditions to the choice of coupling constant.

Electroweak baryogenesis by primordial black holes in Brans-Dicke modified gravity

A successful baryogenesis mechanism is proposed in the cosmological framework of Brans-Dicke modified gravity. Primordial black holes with small mass are produced at the end of the Brans-Dicke field domination era. The Hawking radiation reheats a spherical region around every black hole to a high temperature and the electroweak symmetry is restored there. A domain wall is formed separating the region with the symmetric vacuum from the asymmetric region where electroweak baryogenesis takes place. First order phase transition is not needed. In Brans-Dicke cosmologies black hole accretion can be strong enough to lead to black holes domination which extends the lifetime of black holes and therefore baryogenesis. The analysis of the whole scenario, finally, results in the observed baryon number which can be achieved for a CP-violation angle that is predicted by observationally accepted Two-Higgs Doublet Models. The advantage of our proposed scenario is that naturally provides both black hole domination and more efficient baryogenesis for smaller CP violating angles compared to the same mechanism applied in a FRW cosmological background.

The Quantization of Black Holes, Lower Mass Limit, Temperature, and Lifetime of Black Holes in a Simple Way

We have shown that the permittivity of space grows for a beam of light as the gravitational field increases. Also, we have derived two values for Chandrasekhar limit. Using the necessity of equality of wavelengths in matching systems, we have derived the Hawking black hole temperature and evaporation time in an easier and completely different way, and shown that mass and wavelength of the field and black hole at Schwarzschild sphere are quantized. The extreme simplicity of the present new approach to black holes compared to those based on general relativistic ones should promote it.

The area of a rough black hole

We investigate the consequences for the black hole area of introducing fractal structure for the horizon geometry. We create a three-dimensional spherical analogue of a ‘Koch Snowflake’ using a infinite diminishing hierarchy of touching spheres around the Schwarzschild event horizon. We can create a fractal structure for the horizon with finite volume and infinite (or finite) area. This is a toy model for the possible effects of quantum gravitational spacetime foam, with significant implications for assessments of the entropy of black holes and the universe, which is generally larger than in standard picture of black hole structure and thermodynamics, potentially by very considerable factors. The entropy of the observable universe today becomes S≈10120(1+Δ/2), where 0≤Δ≤1, with Δ=0 for a smooth spacetime structure and Δ=1 for the most intricate. The Hawking lifetime of black holes is also reduced.

Black hole evaporation in Ho\u0159ava\u2013Lifshitz gravity

Hořava–Lifshitz (HL) gravity was formulated in hope of solving the non-renormalization problem in Einstein gravity and the ghost problem in higher derivative gravity theories by violating Lorentz invariance. In this work we consider the spherically symmetric neutral AdS black hole evaporation process in HL gravity in various spacetime dimensions d, and with detailed balance violation parameter 0leqslant epsilon ^2leqslant 1. We find that the lifetime of the black holes under Hawking evaporation is dimensional dependent, with d=4,5 behave differently from dgeqslant 6. For the case of epsilon =0, in d=4,5, the black hole admits zero temperature state, and the lifetime of the black hole is always infinite. This phenomenon obeys the third law of black hole thermodynamics, and implies that the black holes become an effective remnant towards the end of the evaporation. As dgeqslant 6, however, the lifetime of black hole does not diverge with any initial black hole mass, and it is bounded by a time of the order of ell ^{d-1}, similar to the case of Schwarzschild-AdS in Einstein gravity (which corresponds to epsilon ^2=1), though for the latter this holds for all dgeqslant 4. The case of 0<epsilon ^2<1 is also qualitatively similar with epsilon =0.

Page curve for an evaporating black hole

A Page curve for an evaporating black hole in asymptotically flat spacetime is computed by adapting the Quantum Ryu-Takayanagi (QRT) proposal to an analytically solvable semi-classical two-dimensional dilaton gravity theory. The Page time is found to be one third of the black hole lifetime, at leading order in semi-classical corrections. A Page curve is also obtained for a semi-classical eternal black hole, where energy loss due to Hawking evaporation is balanced by an incoming energy flux.

Salecker-Wigner inequalities and the black hole thermodynamics in doubly special relativity

Salecker-Wigner (SW) inequalities are investigated within doubly special relativity (DSR) to take into account the quantum gravitational effects. Based on the modified SW inequalities in DSR, the black hole lifetime and the number of bits required to specify the information content of the black holes are calculated. On the other hand, the black hole is studied from the viewpoint of thermodynamics. The temperature, entropy, specific heat and the emission rate are modified in the presence of DSR effects. The lifetime obtained from the emission rate can be compared with the lifetime coming from the modified SW inequalities. It is shown that they can behave functionally the same. In DSR, the existence of the black hole remnant is predicted from the viewpoint of the SW approach as well as the thermodynamics approach.

Fast radio bursts and the stochastic lifetime of black holes in quantum gravity

Nonperturbative quantum gravity effects might allow a black-to-white hole transition. We revisit this increasingly popular hypothesis by taking into account the fundamentally random nature of the bouncing time. We show that if the primordial mass spectrum of black holes is highly peaked, the expected signal can in fact match the wavelength of the observed fast radio bursts. On the other hand, if the primordial mass spectrum is wide and smooth, clear predictions are suggested and the sensitivity to the shape of the spectrum is studied.

Efficient electroweak baryogenesis by black holes

A novel cosmological scenario, capable of generating the observed baryon number at the electroweak scale for very small charge parity violating angles, is presented. The proposed mechanism can be applied in conventional Friedmann-Robertson-Walker cosmology, but becomes extremely efficient due to accretion in the context of early cosmic expansion with high-energy modifications. Assuming that our Universe is a Randall-Sundrum brane, baryon asymmetry can easily be produced by Hawking radiation of very small primordial black holes. The Hawking radiation reheats a spherical region around every black hole to a high temperature and the electroweak symmetry is restored there. A domain wall is formed separating the region with the symmetric vacuum from the asymmetric region where electroweak baryogenesis takes place. First order phase transition is not needed. The black hole's lifetime is prolonged due to accretion, resulting in strong efficiency of the baryon producing mechanism. The black hole mass range allowed by the mechanism includes masses that are energetically favored to be produced from interactions around the higher dimensional Planck scale.

Analysis on Hawking Radiation and Steady State Universe by Siva’s Theories

Every black hole will have a singularity at its center. The mass ‘M’ and Horizon radius ‘R’ are inter related by an equation M3 = 2.914× 1038 R. As long as it remains as a stable black hole the mass ‘M’ & Horizon Radius ‘R’ will remain constant with M = 6.58×105 Kgs and R = 9.767×10-22 mts. This is the hole connecting all the singularities of the universe. These are always constant for all black holes of the universe. Heavy black holes will lose mass through this hole and will be pumped to other locations of universe to keep the density of the matter created in steady state with the expansion of the universe. The mass loss calculated is 4.953083423× 105 Kg/sec. The mass loss is almost same as that of life time of black hole in Hawking Radiation. Thus the mass loss of black hole is not through hawking radiation it is through the singularity point of black hole.

Impacts of generalized uncertainty principle on black hole thermodynamics and Salecker-Wigner inequalities

We investigate the impacts of Generalized Uncertainty Principle (GUP) proposed by some approaches to quantum gravity such as String Theory and Doubly Special Relativity on black hole thermodynamics and Salecker-Wigner inequalities. Utilizing Heisenberg uncertainty principle, the Hawking temperature, Bekenstein entropy, specific heat, emission rate and decay time are calculated. As the evaporation entirely eats up the black hole mass, the specific heat vanishes and the temperature approaches infinity with an infinite radiation rate.It is found that the GUP approach prevents the black hole from the entire evaporation. It implies the existence of remnants at which the specific heat vanishes. The same role is played by the Heisenberg uncertainty principle in constructing the hydrogen atom. We discuss how the linear GUP approach solves the entire-evaporation-problem.Furthermore, the black hole lifetime can be estimated using another approach; the Salecker-Wigner inequalities. Assuming that the quantum position uncertainty is limited to the minimum wavelength of measuring signal, Wigner second inequality can be obtained. If the spread of quantum clock is limited to some minimum value, then the modified black hole lifetime can be deduced. Based on linear GUP approach, the resulting lifetime difference depends on black hole relative mass and the difference between black hole mass with and without GUP is not negligible.

Change in Energy of Non-Spinning Black Holes w.r.t. the Change in Mass

The present work discusses the derivation of the formula for the change in energy of non-spinning black holes with respect to the change in mass (dE/dM), which gives a constant quantity equal to 8.9998 x 1016 Joule/kg in both categories of X-ray binaries (XRBs) and Active Galactic Nuclei (AGN). This formula can be used to justify the life time of black hole given by Γ = 2.098(M/Mο)3 x 1067 years as proposed by Stephen Hawking, where M and Mο are the mass of the black hole and the sun respectively. The authors also calculate the change in energy and mass of non-spinning black holes with respect to the change in the radius of event horizon as well as (dE/dM) for different test non-spinning black holes in X-ray binaries (XRBs) and Active Galactic Nuclei (AGN).