scholarly journals HAWKING RADIATION AS A MECHANISM FOR INFLATION

2012 ◽  
Vol 21 (11) ◽  
pp. 1242020 ◽  
Author(s):  
SUJOY KUMAR MODAK ◽  
DOUGLAS SINGLETON
Keyword(s):  
Black Hole ◽  
Early Universe ◽  
Power Law ◽  
Negative Pressure ◽  
Hawking Radiation ◽  
Particle Creation ◽  
Hawking Temperature ◽  
Exponential Expansion ◽  
The Universe

The Friedman–Robertson–Walker (FRW) spacetime exhibits particle creation similar to Hawking radiation of a black hole. In this essay we show that this FRW Hawking radiation leads to an effective negative pressure fluid which can drive an inflationary period of exponential expansion in the early universe. Since the Hawking temperature of the FRW spacetime decreases as the universe expands this mechanism naturally turns off and the inflationary stage transitions to a power law expansion associated with an ordinary radiation-dominated universe.

Power law expansion of the early universe for a V (a) = kan potential

2018 ◽  
Vol 33 (01) ◽  
pp. 1850005
Author(s):  
Augusto S. Freitas
Keyword(s):  
Early Universe ◽  
Power Law ◽  
Analytical Solutions ◽  
Scale Factor ◽  
Rigorous Proof ◽  
Exponential Expansion ◽  
True Vacuum ◽  
Classical Potential ◽  
The Universe

In a recent paper, He, Gao and Cai [Phys. Rev. D 89, 083510 (2014)], found a rigorous proof, based on analytical solutions of the Wheeler–DeWitt (WDWE) equation, of the spontaneous creation of the universe from nothing. The solutions were obtained from a classical potential [Formula: see text], where [Formula: see text] is the scale factor. In this paper, we present a complementary (to that of He, Gao and Cai) solution to the WDWE equation with [Formula: see text]. I have found an exponential expansion of the true vacuum bubble for all scenarios. In all scenarios, we found a power law behavior of the scale factor result which is in agreement with another studies.

scholarly journals Gravitational Radiation as the Bremsstrahlung of Superheavy Particles in the Early Universe

Universe ◽  
2020 ◽  
Vol 6 (10) ◽  
pp. 188
Author(s):  
Andrey A. Grib ◽  
Yuri V. Pavlov
Keyword(s):  
Early Universe ◽  
Gravitational Radiation ◽  
Background Radiation ◽  
Particle Creation ◽  
Grand Unification ◽  
Expanding Universe ◽  
The Universe

The number of superheavy particles with the mass of the Grand Unification scale with trans-Planckian energy created at the epoch of superheavy particle creation from the vacuum by the gravitation of the expanding Universe is calculated. In later collisions of these particles, gravitational radiation is radiated playing the role of bremsstrahlung for gravity. The effective background radiation of the Universe is evaluated.

scholarly journals Inflationary universe models and clustering of quasar red shifts

1986 ◽  
Vol 119 ◽  
pp. 509-510
Author(s):  
C. Sivaram
Keyword(s):  
Cosmological Model ◽  
Early Universe ◽  
Hubble Constant ◽  
Matter Density ◽  
Inflationary Universe ◽  
Expansion Phase ◽  
Exponential Expansion ◽  
The Universe ◽  
Inflationary Models ◽  
Universe Models

Recently it has been shown that many of the puzzling features of conventional cosmological models (such as the horizon and flatness problems) could be explained by invoking inflationary models of the early universe with an exponential expansion phase at very early epochs. These models have the added advantage that they are able to make a definite prediction about the present matter density in the universe, i.e. they require that the density be exactly equal to the closure density which in turn can be easily estimated from the Hubble constant now known to within a factor of two. Now if one goes back to an earlier idea that explored the possibility of unusual clustering of quasar redshifts around z = 2 or 3, we get an example of another cosmological model with a definite prediction for the present overall matter density. This is a modified version of the Eddington-Lemaitre type of model which naturally accommodates such features as a clustering of quasars at certain epochs. From these models one can get a prediction for the present matter density which would be an involved function of the Hubble constant and the redshifts at which such clustering occurs. It can be shown that if such clustering had occurred at any z, the present matter density predicted would be substantially smaller than the corresponding closure density. The conclusion is that any clustering of quasar redshifts is incompatiable with inflationary universe models, indirectly providing observational support for these new theories.

Hawking radiation of charged fermions from accelerating and rotating black holes with generalized uncertainty principle

2019 ◽  
Vol 28 (08) ◽  
pp. 1950102
Author(s):  
Muhammad Rizwan ◽  
Khalil Ur Rehman
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Uncertainty Principle ◽  
Hawking Radiation ◽  
Generalized Uncertainty Principle ◽  
Hawking Temperature ◽  
Black Hole Evaporation ◽  
Rotating Black Holes ◽  
Gravity Effects ◽  
Made In

By considering the quantum gravity effects based on generalized uncertainty principle, we give a correction to Hawking radiation of charged fermions from accelerating and rotating black holes. Using Hamilton–Jacobi approach, we calculate the corrected tunneling probability and the Hawking temperature. The quantum corrected Hawking temperature depends on the black hole parameters as well as quantum number of emitted particles. It is also seen that a remnant is formed during the black hole evaporation. In addition, the corrected temperature is independent of an angle [Formula: see text] which contradicts the claim made in the literature.

scholarly journals On catalyzed vacuum decay around a radiating black hole and the crisis of the electroweak vacuum

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
Takumi Hayashi ◽  
Kohei Kamada ◽  
Naritaka Oshita ◽  
Jun’ichi Yokoyama
Keyword(s):  
Black Hole ◽  
Scalar Field ◽  
Standard Model ◽  
Decay Rate ◽  
Early Universe ◽  
Hawking Radiation ◽  
False Vacuum ◽  
Vacuum Decay ◽  
Higgs Vacuum ◽  
The Standard Model

Abstract False vacuum decay is a key feature in quantum field theories and exhibits a distinct signature in the early Universe cosmology. It has recently been suggested that the false vacuum decay is catalyzed by a black hole (BH), which might cause the catastrophe of the Standard Model Higgs vacuum if primordial BHs are formed in the early Universe. We investigate vacuum phase transition of a scalar field around a radiating BH with taking into account the effect of Hawking radiation. We find that the vacuum decay rate slightly decreases in the presence of the thermal effect since the scalar potential is stabilized near the horizon. However, the stabilization effect becomes weak at the points sufficiently far from the horizon. Consequently, we find that the decay rate is not significantly changed unless the effective coupling constant of the scalar field to the radiation is extremely large. This implies that the change of the potential from the Hawking radiation does not help prevent the Standard Model Higgs vacuum decay catalyzed by a BH.

scholarly journals SUPERHEAVY PARTICLES IN FRIEDMANN COSMOLOGY AND THE DARK MATTER PROBLEM

2002 ◽  
Vol 11 (03) ◽  
pp. 433-436 ◽  
Author(s):  
A. A. GRIB ◽  
YU. V. PAVLOV
Keyword(s):  
Dark Matter ◽  
Gravitational Field ◽  
Early Universe ◽  
Particle Creation ◽  
Baryon Number ◽  
Matter Density ◽  
Friedmann Model ◽  
Dark Matter Density ◽  
The Universe

The model of creation of observable particles and particles of the dark matter, considered to be superheavy particles, due to particle creation by the gravitational field of the Friedmann model of the early Universe is given. Estimates on the parameters of the model leading to observable values of the baryon number of the Universe and the dark matter density are made.

scholarly journals The emergence of the first star-free atomic cooling haloes in the Universe

2020 ◽  
Vol 492 (2) ◽  
pp. 3021-3031 ◽  
Author(s):  
John A Regan ◽  
John H Wise ◽  
Brian W O’Shea ◽  
Michael L Norman
Keyword(s):  
Black Hole ◽  
Early Universe ◽  
Metal Enrichment ◽  
Massive Black Hole ◽  
Metal Free ◽  
Physical Conditions ◽  
Radiation Fields ◽  
Atomic Cooling ◽  
The Universe ◽  
Massive Galaxy

ABSTRACT Using the Renaissance suite of simulations, we examine the emergence of pristine atomic cooling haloes that are both metal free and star free in the early universe. The absence of metals prevents catastrophic cooling, suppresses fragmentation, and may allow for the formation of massive black hole seeds. Here we report on the abundance of pristine atomic cooling haloes found and on the specific physical conditions that allow for the formation of these direct-collapse-black hole (DCBH) haloes. In total, in our simulations we find that 79 DCBH haloes form before a redshift of 11.6. We find that the formation of pristine atomic haloes is driven by the rapid assembly of the atomic cooling haloes with mergers, both minor and/or major, prior to reaching the atomic cooling limit a requirement. However, the ability of assembling haloes to remain free of (external) metal enrichment is equally important and underlines the necessity of following the transport of metals in such simulations. The candidate DCBH-hosting haloes we find have been exposed to mean Lyman–Werner radiation fields of J21 ∼1 and typically lie at least 10 kpc (physical) from the nearest massive galaxy. The growth rates of the haloes reach values of greater than 107$\rm {M_{\odot }}~$ per unit redshift, leading to significant dynamical heating and the suppression of efficient cooling until the halo crosses the atomic cooling threshold. Finally, we also find five synchronized halo candidates where pairs of pristine atomic cooling haloes emerge that are both spatially and temporally synchronized.

HOMOGENEOUS ANISOTROPIC COSMOLOGICAL MODELS WITH VISCOUS FLUID AND HEAT FLOW IN LYRA'S GEOMETRY

2009 ◽  
Vol 24 (23) ◽  
pp. 1847-1856 ◽  
Author(s):  
SHRI RAM ◽  
M. K. VERMA ◽  
MOHD ZEYAUDDIN
Keyword(s):  
Power Law ◽  
Bianchi Type ◽  
Big Bang ◽  
Field Equations ◽  
Type Singularity ◽  
Exponential Expansion ◽  
Imperfect Fluid ◽  
Lyra’S Geometry ◽  
Type V ◽  
The Universe

In this paper, a spatially homogeneous and anisotropic Bianchi type V model filled with an imperfect fluid with both viscosity and heat conduction is investigated within the framework of Lyra's geometry. Exact solutions of the field equations are obtained by applying a special law of variation for Hubble's parameter which yields a constant value of the deceleration parameter. Two different physically viable models of the universe are presented in two types of cosmologies, one with power-law expansion and other one with exponential expansion. Cosmological model with power-law expansion has an initial big-bang type singularity at t = 0 whereas the model with exponential expansion has a singularity in the infinite past. The physical and dynamical properties of the models are discussed.

scholarly journals PRIMORDIAL BLACK HOLES, HAWKING RADIATION AND THE EARLY UNIVERSE

2005 ◽  
Vol 20 (21) ◽  
pp. 1573-1576 ◽  
Author(s):  
PAUL H. FRAMPTON ◽  
THOMAS W. KEPHART
Keyword(s):  
Black Holes ◽  
Early Universe ◽  
Hawking Radiation ◽  
Cold Dark Matter ◽  
Primordial Black Holes ◽  
Gamma Emission ◽  
High Concentration ◽  
Age Of The Universe ◽  
Speculative Hypothesis ◽  
The Universe

The 511 keV gamma emission from the galactic core may originate from a high concentration (~ 1022) of primordial black holes (PBHs) in the core, each of whose Hawking radiation includes ~ 1021 positrons per second. The PBHs we consider are taken as near the lightest with longevity greater than the age of the universe (mass ~ 1012 kg ; Schwarzschild radius ~ 1 fm ). These PBHs contribute only a small fraction of cold dark matter, Ω PBH ~ 10-8. This speculative hypothesis, if confirmed implies the simultaneous discovery of Hawking radiation and an early universe phase transition.

BARYOGENESIS FROM BLACK HOLE EVAPORATION

1995 ◽  
Vol 04 (04) ◽  
pp. 517-529 ◽  
Author(s):  
A.S. MAJUMDAR ◽  
P. DAS GUPTA ◽  
R.P. SAXENA
Keyword(s):  
Phase Transition ◽  
Black Holes ◽  
Black Hole ◽  
Hawking Radiation ◽  
Baryon Asymmetry ◽  
False Vacuum ◽  
Black Hole Evaporation ◽  
Inflationary Phase ◽  
The Universe

The possibility of baryogenesis through the evaporation of black holes formed during extended inflation is explored. These black holes are produced due to the collapse of trapped regions of false vacuum during the inflationary phase transition. Immediately after formation, the accretion of mass from the surrounding hot radiation bath in the universe is shown to be an important effect. This causes the lifetime of the black holes to be considerably elongated before they evaporate out through the process of Hawking radiation. It is shown that a sufficient number of black holes last up to well past the electroweak era and hence contribute to the surviving baryon asymmetry in the universe.

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