Hawking Evaporation Process Research Articles

Influences of modified Chaplygin dark fluid around a black hole

In this work, we study a static, spherically charged AdS black hole within a modified cosmological Chaplygin gas (MCG), adhering to the calorific equation of state, as a unified dark fluid model of dark energy and dark matter. We explore the influence of model parameters on several characteristics of the MCG-motivated charged AdS black hole (MCG-AdSBH), including the geodesic structure and some astrophysical phenomena such as null trajectories, shadow silhouettes, light deflection angles, and the determination of greybody bounds. We then discuss how the model parameters affect the Hawking temperature, remnant radius, and evaporation process of the MCG-AdSBH. Quasinormal modes are also investigated using the eikonal approximation method. Constraints on the MCG-AdSBH parameters are derived from EHT observations of M87* and Sgr A*, suggesting that MCG-AdSBH could be strong candidates for astrophysical black hole.

Effects of thermal fluctuations on the evaporation of AdS Schwarzschild scalar tensor vector gravity black hole

The Hawking evaporation process has important implications for our understanding of the universe, as it suggests that black holes are not eternal and can eventually evaporate away completely. We evaluate the Hawking evaporation process of AdS Schwarzschild scalar-tensor-vector gravity black hole by using Stefan-Boltzmann law and find out that Hawking evaporation rate depends on the AdS radius l and deviation parameter α of the scalar-tensor-vector gravity. We analyze that for small values of AdS radius l and positive deviation parameter α black hole evaporates quickly. While there is exponential increase in lifetime of the black hole for large AdS radius l and negative deviation parameter α. Moreover, we find out thermodynamical quantities like Helmholtz free energy, internal energy, pressure, enthalpy, Gibbs free energy and specific heat and show that how deviation parameter α and the correction parameter ζ of the first order corrected entropy play vital role on the stability and phase transitions of the black holes.

Effect of modified gravity on the Hawking evaporation of charged AdS black holes

We study the impact of rainbow and Einstein bumblebee modified theories of gravity on the Hawking evaporation process of the black holes. After evaluating the basic thermodynamical quantities, we find out impact parameter b = (angular momentum )/(energy of the emitted particles), which control the emission of the particles and the photon orbit of the black hole in modified theories of gravity. We utilize the well-known Stefan-Boltzmann law to obtain the relationship of black hole mass M against its lifetime t. The numerical results of black hole mass versus lifetime t show that initially the mass of black hole in modified gravity decreases rapidly and later evaporation process becomes slower when temperature reduces to zero. The black hole requires huge time to fully evaporate which is consistent result with 3rd law of thermodynamics for black holes. We observe that increasing values of AdS length l increases evaporation time and increasing value of rainbow parameter η results in slowing down the evaporation process. Moreover, we analyze that uncharged black holes evaporate quickly as compared to charged black hole and black hole in higher dimensions required huge time to fully evaporate as compared to black hole in small dimensions.

Black hole complementarity from microstate models: a study of information replication and the encoding in the black hole interior

We study how the black hole complementarity principle can emerge from quantum gravitational dynamics within a local semiclassical approximation. Further developing and then simplifying a microstate model based on the fragmentation instability of a near-extremal black hole, we find that the key to the replication (but not cloning) of infalling information is the decoupling of various degrees of freedom. The infalling matter decouples from the interior retaining a residual time-dependent quantum state in the hair which encodes the initial state of the matter non-isometrically. The non-linear ringdown of the interior after energy absorption and decoupling also encodes the initial state, and transfers the information to Hawking radiation. During the Hawking evaporation process, the fragmented throats decouple from each other and the hair decouples from the throats. We find that the hair mirrors infalling information after the decoupling time which scales with the logarithm of the entropy (at the time of infall) when the average mass per fragmented throat (a proxy for the temperature) is held fixed. The decoding protocol for the mirrored information does not require knowledge of the interior, and only limited information from the Hawking radiation, as can be argued to be necessitated by the complementarity principle. We discuss the scope of the model to illuminate various aspects of information processing in a black hole.

Updated constraints on primordial black hole evaporation

The Hawking evaporation process, leading to the production of detectable particle species, constrains the abundance of light black holes, presumably of primordial origin. Here, we reconsider and correct constraints from soft gamma-ray observations, including of the gamma-ray line, at 511 keV, produced by electron-positron pair-annihilation, where positrons originate from black hole evaporation. First, we point out that the INTEGRAL detection of the Large Magellanic Cloud provides one of the strongest bounds attainable with present observations; and that future MeV gamma-ray telescopes, such as GECCO, will greatly enhance such constraints. Second, we discuss issues with previous limits from the isotropic flux at 511 keV and we provide updated, robust constraints from recent measurements of the diffuse Galactic soft gamma-ray emission and from the isotropic soft gamma-ray background.

Hawking evaporation, shadow images, and thermodynamics of black holes through deflection angle

We study the Hawking evaporation process of the exact black hole with nonlinear electrodynamics for positive and negative coupling constant zeta . We provide a new perspective to study the thermodynamics of exact black hole through deflection angle formalism. We also evaluate the shadow images in the presence of deflection images for this black hole. Moreover, we consider the Gibbs energy optical dependence to investigate the Hawking-Page transition. We observe that evaporation rate depends upon zeta and black hole evaporates more quickly for positive zeta as compared to negative zeta . For the case zeta =-1, the black hole’s lifetime become infinite, which makes the black hole a remnant and the third law of black hole thermodynamics holds in this scenario. We show that the thermal variations in the deflection angle can be used to determine the stable and unstable phases of the black hole. Our findings show that large and small phase transitions of black hole occur at a specific value of the deflection angle.

Kinetics and its turnover of Hawking-Page phase transition under the black hole evaporation

The thermodynamics and the kinetics of Hawking-Page phase transition were studied previously based on the free energy landscape. The anti--de Sitter black hole can evaporate if imposing the absorbing boundary conditions at infinity. We suggest that the kinetics of Hawking-Page phase transition should be governed by the reaction-diffusion equation, where the Hawking evaporation plays the role of the reaction on the background of the free-energy landscape. By calculating the mean first-passage time from the large black hole phase to the thermal gas phase, we show that the phase transition can occur more easily under the Hawking radiation. In particularly, a kinetic turnover is observed when increasing the ensemble temperature or the frictions. This kinetic turnover can be viewed as the dynamical phase transition to identify the time scale where Hawking evaporation process is comparable to Hawking-Page phase transition.

Hawking radiation may violate the Penrose cosmic censorship conjecture

We analyze the Hawking evaporation process of Reissner–Nordström black holes. It is shown that the characteristic radiation quanta emitted by the charged black holes may turn near-extremal black-hole spacetimes into horizonless naked singularities. This analysis therefore reveals the intriguing possibility that the semi-classical Hawking evaporation process of black holes may violate the fundamental Penrose cosmic censorship conjecture.

Primordial Regular Black Holes: Thermodynamics and Dark Matter

The possibility that dark matter particles could be constituted by extreme regular primordial black holes is discussed. Extreme black holes have zero surface temperature, and are not subjected to the Hawking evaporation process. Assuming that the common horizon radius of these black holes is fixed by the minimum distance that is derived from the Riemann invariant computed from loop quantum gravity, the masses of these non-singular stable black holes are of the order of the Planck mass. However, if they are formed just after inflation, during reheating, their initial masses are about six orders of magnitude higher. After a short period of growth by the accretion of relativistic matter, they evaporate until reaching the extreme solution. Only a fraction of 3.8 × 10−22 of relativistic matter is required to be converted into primordial black holes (PBHs) in order to explain the present abundance of dark matter particles.

The Hawking cascades of gravitons from higher-dimensional Schwarzschild black holes

It has recently been shown that the Hawking evaporation process of $(3+1)$-dimensional Schwarzschild black holes is characterized by the dimensionless ratio $\eta\equiv\tau_{\text{gap}}/\tau_{\text{emission}}\gg1$, where $\tau_{\text{gap}}$ is the characteristic time gap between the emissions of successive Hawking quanta and $\tau_{\text{emission}}$ is the characteristic timescale required for an individual Hawking quantum to be emitted from the Schwarzschild black hole. This strong inequality implies that the Hawking cascade of gravitons from a $(3+1)$-dimensional Schwarzschild black hole is extremely {\it sparse}. In the present paper we explore the semi-classical Hawking evaporation rates of {\it higher}-dimensional Schwarzschild black holes. We find that the dimensionless ratio $\eta(D)\equiv{{\tau_{\text{gap}}}/{\tau_{\text{emission}}}}$, which characterizes the Hawking emission of gravitons from the $(D+1)$-dimensional Schwarzschild black holes, is a {\it decreasing} function of the spacetime dimension. In particular, we show that higher-dimensional Schwarzschild black holes with $D\gtrsim 10$ are characterized by the relation $\eta(D)<1$. Our results thus imply that, contrary to the $(3+1)$-dimensional case, the characteristic Hawking cascades of gravitons from these higher-dimensional black holes have a {\it continuous} character.

Vacuum metastability with black holes

We consider the possibility that small black holes can act as nucleation seeds for the decay of a metastable vacuum, focussing particularly on the Higgs potential. Using a thin-wall bubble approximation for the nucleation process, which is possible when generic quantum gravity corrections are added to the Higgs potential, we show that primordial black holes can stimulate vacuum decay. We demonstrate that for suitable parameter ranges, the vacuum decay process dominates over the Hawking evaporation process. Finally, we comment on the application of these results to vacuum decay seeded by black holes produced in particle collisions.

The Hawking evaporation process of rapidly-rotating black holes: an almost continuous cascade of gravitons

It is shown that rapidly-rotating Kerr black holes are characterized by the dimensionless ratio \(\tau _{\text {gap}}/\tau _{\text {emission}}=O(1)\), where \(\tau _{\text {gap}}\) is the average time gap between the emissions of successive Hawking quanta and \(\tau _{\text {emission}}\) is the characteristic timescale required for an individual Hawking quantum to be emitted from the black hole. This relation implies that the Hawking cascade from rapidly-rotating black holes has an almost continuous character. Our results correct some inaccurate claims that recently appeared in the literature regarding the nature of the Hawking black-hole evaporation process.

STABLE TeV BLACK HOLE REMNANTS AT THE LHC: DISCOVERY THROUGH DI-JET SUPPRESSION, MONO-JET EMISSION AND A SUPERSONIC BOOM IN THE QUARK–GLUON PLASMA

The production of large extra dimension (LXD) black holes (BHs), with a new, fundamental mass scale of Mf = 1 TeV , has been predicted to occur at the Large Hadron Collider, LHC, with the formidable rate of 108 per year in p-p collisions at full energy, 14 TeV, and at full luminosity. We show that such LXD-BH formation will be experimentally observable at the LHC by the complete disappearance of all very high pt (&gt; 500 GeV) back-to-back correlated Di-Jets of total mass M &gt; Mf = 1 TeV , in the large detectors ALICE, ATLAS and CMS. We suggest complementing this clear cut-off signal at M &gt; 2*500 GeV in the di-jet-correlation function by detecting the subsequent, Hawking-decay products of the LXD-BHs, namely either multiple high energy (&gt; 100 GeV) SM Mono-Jets (i.e. away-side jet missing), sprayed off the evaporating BHs isentropically into all directions or the thermalization of the multiple overlapping Hawking-radiation in a Heckler–Kapusta-plasma: The extreme energy density of the Hawking Radiation may yield a Heckler–Kapusta–Hawking quark–gluon plasma of SM — and SUSY — particles at temperatures above the electroweak phase transition, which hydrodynamically (isentropically) evolves and cools until the quark–hadron phasetransition and chemical freezeout at T ~ 100 MeV is reached. Microcanonical quantum statistical calculations of the Hawking evaporation process for these LXD-BHs show that cold black hole remnants (BHRs) of mass ~ Mf remain leftover as the ashes of these spectacular di-jet-suppressed events. The BHRs are charged and can be detected as a track in the Central TPC of ALICE. Strong di-jet suppression is also expected with heavy ion beams at the LHC, due to quark–gluon-plasma induced jet attenuation at medium to low jet energies, pt &lt; 200 GeV . The (mono-) jets in these events can be used to trigger tsunami-emission of secondary compressed QCD-matter at well defined Mach-angles, both at the trigger side and at the awayside (missing) jet. The Machshock angles allow for a direct measurement of both the equation of state EoS and the speed of sound cs via supersonic bang in the "big bang" matter. We discuss the importance of the underlying strong collective flow — the gluon storm — of the QCD matter for the formation and evolution of these Machshock cones. We predict a significant deformation of Mach shocks from the gluon storm in central Au + Au collisions at RHIC and LHC energies, as compared to the case of weakly coupled jets propagating through a static medium. A possible complete stopping of pt &gt; 50 GeV jets at the LHC in 2–3 fm yields nonlinear high density Mach shocks in the quark–gluon plasma, which can be studied in the complex emission and disintegration pattern of the possibly supercooled matter. We report on first full three-dimensional fluid dynamical studies of the strong effects of a first order phase transition on the evolution and the tsunami-like Mach shock emission of the QCD matter.

Quantum-corrected black hole thermodynamics to all orders in the Planck length

We investigate the effects to all orders in the Planck length from a generalized uncertainty principle (GUP) on black holes thermodynamics. We calculate the corrected Hawking temperature, entropy, and examine in details the Hawking evaporation process. As a result, the evaporation process is accelerated and the evaporation end-point is a zero entropy, zero heat capacity and finite non-zero temperature black hole remnant (BHR). In particular we obtain a drastic reduction of the decay time, in comparison with the results obtained in the Hawking semi classical picture and with the GUP to leading order in the Planck length.

Spacetime structure of an evaporating black hole in quantum gravity

The impact of the leading quantum gravity effects on the dynamics of the Hawking evaporation process of a black hole is investigated. Its spacetime structure is described by a renormalization group improved Vaidya metric. Its event horizon, apparent horizon, and timelike limit surface are obtained by taking the scale dependence of Newton's constant into account. The emergence of a quantum ergosphere is discussed. The final state of the evaporation process is a cold, Planck size remnant.

PRIMARY SCALAR HAIR OF BLACK HOLES IN EFFECTIVE STRING THEORY

Black holes in string theories can be studied by means of effective gravity-matter actions. These contain, among others, non-minimally coupled scalar fields, as the dilaton and moduli arising from the compactification of the extra dimensions1. The presence of non-minimal couplings prevents the application of the well known no-hair theorems2, so that it is possible to find regular black hole solutions with scalar hair. Solutions with non-trivial dilaton hair are known for Maxwell3 and Gauss-Bonnet4 black holes. In these cases the dilaton charge is a function of the other parameters of the solutions (secondary hair). However, it has recently been shown that when moduli fields are taken into account as well, one can obtain solutions where the scalar charges of the moduli are independent parameters (primary scalar hair)5,6. The thermodynamics of these black holes has been investigated. In particular, in the Maxwell case a condition for extremality has been obtained, which sets a lower bound for the mass in terms of the magnetic and scalar charges7. Similarly in the Gauss-Bonnet case, a minimal allowed value for the mass has been found, which depends only on the scalar charges and can be interpreted as a ground state for the Hawking evaporation process of the black hole6.

Dilatonic black holes with a Gauss-Bonnet term

We discuss black holes in an effective theory derived from a superstring model, which includes a dilaton field, a gauge field and the Gauss-Bonnet term. Assuming U(1) or SU(2) symmetry for the gauge field, we find four types of spherically symmetric solutions, i.e., a neutral, an electrically charged, a magnetically charged and a ``colored'' black hole, and discuss their thermodynamical properties and fate via the Hawking evaporation process. For neutral and electrically charged black holes, we find critical point and a singular end point. Below the mass corresponding to the critical point, nosolution exists, while the curvature on the horizon diverges and anaked singularity appears at the singular point. A cusp structure in the mass-entropy diagram is found at the critical point and black holes on the branch between the critical and singular points become unstable. For magnetically charged and ``colored" black holes, the solution becomes singular just at the end point with a finite mass. Because the black hole temperature is always finite even at the critical point or the singular point, we may conclude that the evaporation process will not be stopped even at the critical point or the singular point, and the black hole will move to a dynamical evaporation phase or a naked singularity will appear.

Classical and semiclassical properties of extremal black holes with dilaton and modulus fields

We discuss both classical and semiclassical properties of extremal black holes in theories where the dilaton and a modulus field are present. We find that the corresponding 2d geometry is asymptotically anti-de Sitter rather than asymptotically flat as in the purely dilatonic case. This fact has many important consequences, which we analyze at length, both for the classical behaviour and for the thermodynamical properties of the black hole. We also study the Hawking evaporation process in the semiclassical approximation. The calculations strongly indicate the emergence of a stable ground state as the end point of the process. Some comments are made about the relevance of our results for the problem of information loss in black hole in physics.

A new mechanism of releasing gravitational energy in curved spacetime

I give a new mechanism of releasing gravitational energy in curved spacetime. It is different from the Penrose process, the Starobinsky-Unruh process, or the Hawking evaporation process [1]. The existence of this process is proved for the specific instances of the Kerr and the Schwarzschild metrics and formulae (18) and (21) give the net energy released.