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 The Expansion of the Universe

2020 ◽  
Vol 8 (07) ◽  
pp. 25-31
Author(s):  
Dr. Andreas Gimsa
Keyword(s):  
Background Radiation ◽  
Expanding Universe ◽  
Stellar Radiation ◽  
Expansion Of The Universe ◽  
Accelerated Growth ◽  
The Universe ◽  
Physical Quantities

The expansion of the universe is explained, calculated and graphically displayed. The 3K background radiation is examined and interpreted as reflected and distributed stellar radiation. The role of entropy in cosmology is discussed. In our expanding universe it must remain constant. Physical quantities previously assumed to be constant are worked out to be variable. It is explained why the measured redshift is not due to an accelerated growth of the universe.

scholarly journals The Spectrum of Density Perturbations in an Expanding Universe

1974 ◽  
Vol 63 ◽  
pp. 175-193
Author(s):  
Joseph Silk
Keyword(s):  
Large Scale ◽  
Background Radiation ◽  
Large Scale Structure ◽  
Challenging Problem ◽  
Expanding Universe ◽  
Related Matter ◽  
Widespread Acceptance ◽  
Density Perturbations ◽  
Density Inhomogeneities ◽  
The Universe

Perhaps the most challenging problem confronting a cosmologist is to reconcile the observed large-scale structure of the Universe with the Friedmann-Lemaître cosmological models that have gained such widespread acceptance in recent years (cf. however the alternative viewpoint, as exemplified in this Symposium by Arp and others). In this review, I shall look anew at the spectrum of density inhomogeneities that survive decoupling of matter and radiation at z ~ 1000 and provide the primordial fluctuations that can eventually generate galaxies. A closely related matter, that of the associated fluctuations in the background radiation, is discussed elsewhere in this volume by Doroshkevich, Sunyaev and Zel'dovich.

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.

NUCLEON PROPERTIES IN THE EXPANDING UNIVERSE

2003 ◽  
Vol 18 (02n06) ◽  
pp. 374-383
Author(s):  
W-Y. PAUCHY HWANG
Keyword(s):  
Phase Transition ◽  
Early Universe ◽  
Mass Formula ◽  
The State ◽  
Nucleon Mass ◽  
Expanding Universe ◽  
Qcd Phase Transition ◽  
Qcd Vacuum ◽  
The Universe

Our universe expands and cools. The electroweak (EW) phase transition, which endows masses to the various particles, and QCD phase transition, which gives rise to confinement of quarks and gluons within hadrons in the true QCD vacuum, Would presumably have taken place in the early universe, respectively, at around 10-11 sec and at a time between 10-5 sec and 10-4 sec, or at the temperature of about 300 GeV and of about 150 MeV, respectively. It is clear that the nucleon mass [Formula: see text], the axial coupling [Formula: see text], and other nucleon parameters evolve as the universe evolves, thereby serving as an important gauge for understanding the state of the Universe.

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.

scholarly journals Physical observers, T-vacuum and Unruh like effect in the radiation dominated early universe

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Sujoy K. Modak
Keyword(s):  
Excited State ◽  
Early Universe ◽  
Particle Creation ◽  
Vacuum State ◽  
Unruh Effect ◽  
Two Dimensional ◽  
Creation Process ◽  
Flat Spacetime ◽  
Set Up

Abstract We report the existence of an Unruh like effect, for physical observers (cosmo- logical and comoving observers) in the radiation dominated early universe, which is possible due to the discovery of a new vacuum state (referred here as the T−vacuum). Both the comoving and the cosmological observers, who are crucial in our understanding of cosmology, observe this T−vacuum as a particle excited state and are able to detect radiation due to particle creation. We draw a robust analogy with the Unruh effect, whereby — (i) the physical observers here are closely analogous to the accelerated (Rindler) observers in the flat spacetime, and (ii) the T−vacuum plays the role of the Minkowski vacuum state which contains particles when viewed from the physical observers frame. Our analogy is further supported by a proof of well-defined (hadamard) behavior of the T−vacuum in the entire spacetime. All our analysis of the particle creation process is done here within a two dimensional set up.

scholarly journals Fifty years of the calculation of the density of particles created in the early Friedmann Universe

2020 ◽  
Vol 35 (02n03) ◽  
pp. 2040034 ◽  
Author(s):  
A. A. Grib ◽  
Yu. V. Pavlov
Keyword(s):  
Particle Creation ◽  
Friedmann Universe ◽  
Expanding Universe ◽  
Scalar Particles ◽  
Number Of Particles

The problem of particle creation in cosmology concerning whether the results for the number of particles are infinite or finite is discussed for scalar and spinor particles in Friedmann expanding Universe. It is shown that the results are always finite if one puts in case of scalar particles creation a special term into the Lagrangian. Numerical estimates of the effect of particle creation are made. The role of creation of superheavy particles in cosmology is discussed.

scholarly journals COSMOLOGICAL SOLUTION IN M-THEORY ON S1/Z2

1999 ◽  
Vol 08 (02) ◽  
pp. 153-160 ◽  
Author(s):  
KARIM BENAKLI
Keyword(s):  
Cosmological Solution ◽  
Radial Coordinate ◽  
Expanding Universe ◽  
Instanton Solution ◽  
Tunneling Process ◽  
Yang Mills ◽  
Lorentzian Signature ◽  
M Theory ◽  
The Universe

We provide the first example of a cosmological solution of the Horava–Witten supergravity. This solution is obtained by exchanging the role of time with the radial coordinate of the transverse space to the five-brane soliton. On the boundary, this corresponds to rotating an instanton solution into a tunneling process in a space with Lorentzian signature, leading to an expanding universe. Due to the freedom to choose different nontrivial Yang–Mills backgrounds on the boundaries, the two walls of the universe (visible and hidden worlds) expand differently. However at late times the anisotropy is washed away by gravitational interactions.

scholarly journals Dynamics and Clusters of Galaxies

1974 ◽  
Vol 62 ◽  
pp. 273-284
Author(s):  
D. G. Saari
Keyword(s):  
Virial Theorem ◽  
Gravitational Force ◽  
Clusters Of Galaxies ◽  
Expanding Universe ◽  
Evolution Of The Universe ◽  
Mathematical Probability ◽  
The Masses ◽  
The Universe

Under the assumption that the inverse square central force law is a good approximation to the gravitational force, at least for large distances, the different possibilities for the evolution of the Universe are sketched. Several of the possibilities lead naturally to a dynamical classification of clusters of galaxies in an expanding universe. In one of the classifications the galaxies must define configurations which are functions of the masses. The virial theorem approach of determining masses of galaxies in a cluster is briefly examined. Some tentative statements concerning a dynamical explanation of the local hypothesis for quasars are advanced. Finally, the role of mathematical probability in predicting the behavior of the Universe is discussed.

scholarly journals Leptogenesis in the Universe

2012 ◽  
Vol 2012 ◽  
pp. 1-59 ◽  
Author(s):  
Chee Sheng Fong ◽  
Enrico Nardi ◽  
Antonio Riotto
Keyword(s):  
Early Universe ◽  
Finite Temperature ◽  
Baryon Asymmetry ◽  
Quantum Corrections ◽  
Sterile Neutrinos ◽  
Lepton Asymmetry ◽  
The Universe

Leptogenesis is a class of scenarios in which the cosmic baryon asymmetry originates from an initial lepton asymmetry generated in the decays of heavy sterile neutrinos in the early Universe. We explain why leptogenesis is an appealing mechanism for baryogenesis. We review its motivations and the basic ingredients and describe subclasses of effects, like those of lepton flavours, spectator processes, scatterings, finite temperature corrections, the role of the heavier sterile neutrinos, and quantum corrections. We then address leptogenesis in supersymmetric scenarios, as well as some other popular variations of the basic leptogenesis framework.

Sign in / Sign up

Export Citation Format

Share Document