Showing papers on "Cosmology published in 1987"
01 Jan 1987
TL;DR: A new inflationary universe scenario is suggested in this paper, which is free of the shortcomings of the previous one and provides a possible solution of the horizon, flatness, homogeneity and isotropy problems in cosmology.
Abstract: A new inflationary universe scenario is suggested, which is free of the shortcomings of the previous one and provides a possible solution of the horizon, flatness, homogeneity and isotropy problems in cosmology, and also a solution of the primordial monopole problem in grand unified theories.
3,542 citations
TL;DR: In this article, the physics of light pseudoscalars (axions, majorons and familons) and their effects in cosmology are reviewed. And the allowed band of the axion scale 10 8 GeV ≲ F a ≲ 10 12 GeV is discussed.
858 citations
TL;DR: In this article, an age of 9.3 + or - 2.0 Gyr is derived for the Galactic disk on the basis of comparisons between the sudden drop in the observed luminosity distribution and theoretical evolutionary white dwarf models and allowance for a mean prewhite-dwarf lifetime of 0.3 Gyr.
Abstract: An age of 9.3 + or - 2.0 Gyr is derived for the Galactic disk on the basis of comparisons between the sudden drop in the observed luminosity distribution and theoretical evolutionary white dwarf models and allowance for a mean prewhite-dwarf lifetime of 0.3 Gyr. To obtain the age of the universe, the time between the big bang and the first appearance of stars in the Galactic disk is added. The age of the universe is estimated to be 10.3 + or - 2.2 Gyr.
380 citations
TL;DR: In this article, the authors consider the best way to fit an idealised exactly homogeneous and isotropic universe model to a realistic lumpy universe using the standard Robertson-Walker models.
Abstract: This paper considers the best way to fit an idealised exactly homogeneous and isotropic universe model to a realistic ('lumpy') universe; whether made explicit or not, some such approach of necessity underlies the use of the standard Robertson-Walker models as models of the real universe. Approaches based on averaging, normal coordinates and null data are presented, the latter offering the best opportunity to relate the fitting procedure to date obtainable by astronomical observations.
215 citations
TL;DR: In this paper, the Compton-getting interpretation of the dipole anisotropy in the microwave background is presented as a diagnostic of the weak asymmetry exhibited by the cosmic X-ray background.
199 citations
Book•
01 Jan 1987
TL;DR: In this article, the authors present the original observations and fundamental data on quasars and galaxies, and explain why they have concluded that far from being the most distant objects in the universe, Quasars are associated in space with relatively nearby galaxies.
Abstract: For twenty years, the author has contested the 'establishment' view of quasars as the most distant objects in the universe. In this book, Arp presents the original observations and fundamental data on quasars and galaxies, and explains why he has concluded that: far from being the most distant objects in the universe, quasars are associated in space with relatively nearby galaxies; quasars' enormous redshifts do not arise from the expansion of the universe, but rather are intrinsic properties of the quasars themselves; many galaxies show redshift anomalies related to quasars' redshifts; quasars and galaxies have an origin far different from that assumed in the 'standard' big-bang model of the universe; many astronomers, despite the accumulation of compelling evidence, defend what Arp believes is a fundamentally incorrect assumption about cosmic objects.
192 citations
TL;DR: In this article, it was shown that a bent global string straightens itself out by dissipation into Nambu-Goldstone (NG) bosons in the order of one oscillation time and that the spectrum of radiated NG bosons is 1/k.
170 citations
156 citations
129 citations
TL;DR: The cosmologies based on Lyra's manifold, with constant gauge-vector which have been studied in the literature, will either include a creation field and be equal to Hoyle's creation field cosmology, or contain a special vacuum fluid which together with the gauge vector term may be considered as a cosmological term.
Abstract: It is pointed out that the cosmologies based on Lyra's manifold, with constant gauge-vector which have been studied in the literature, will either include a creation field and be equal to Hoyle's creation field cosmology, or contain a special vacuum fluid which together with the gauge-vector term may be considered as a cosmological term. In the latter case the solutions are equal to the general relativistic cosmologies with a cosmological term.
TL;DR: An analytic approach to the phase space for a network of cosmic strings is presented, based on earlier work of Frautschi and Carlitz, and correctly predicts the main features of the network at formation, and is in good agreement with the picture emerging from string simulations.
Abstract: An analytic approach to the phase space for a network of cosmic strings is presented, based on earlier work of Frautschi and Carlitz. It correctly predicts the main features of the network at formation, and is in good agreement with the picture emerging from string simulations. Our results also have important implications for superstrings or heterotic strings in the early Universe.
TL;DR: In this article, it was concluded that there are no significant constraints on possible spatial variations in Newton's constant at large distances, and the implications of a simple force law correction to Newtonian gravity from planetary to cosmological distances are discussed.
Abstract: Experimental or observational tests of the 1/r-squared gravitational force law are weak or nonexistent at length scales beyond the solar system. This is because at long distances all astrophysical estimates of mass density based on dynamics give larger values than corresponding measurements based on observed luminosity and local mass-to-luminosity ratios. The discrepancy generally increases with increasing distance, from galactic lengths to at least cluster scales near 10 Mpc, and is usually interpreted as evidence for missing mass. From an empirical perspective that does not recognize the existence of dark matter unless it is nondynamically confirmed, it could be concluded that there are no significant constraints on possible spatial variations in Newton's constant at large distances. The implications of a simple force law correction to Newtonian gravity from planetary to cosmological distances are discussed. 37 references.
TL;DR: In this article, an observed anisotropy in the sky emission at a level of δT/T = 3.7×l0-5 has been detected (T is temperature), interpreted as an upper limit to the cosmic microwave background fluctuations.
Abstract: Extensive high sensitivity observations of the cosmic microwave background have been made on an angular scale of 8° covering a substantial fraction of the northern sky. An observed anisotropy in the sky emission at a level of δT/T = 3.7×l0–5 has been detected (T is temperature). This level should strictly be interpreted as an upper limit to the cosmic microwave background fluctuations. It is possibly the direct imprint of density perturbations in the early Universe.
TL;DR: In this paper, a natural thermal interpretation of the cosmological scenario is suggested in which the energy of the vacuum background is a variable function of the cosmic time; it is also shown that in this context one can easily formulate a simple phenomenological model which helps understanding, without fine-tuning, the extreme smallness of the present value of the Cosmological constant.
TL;DR: In this paper, the authors discuss cosmologies where the cosmological constant λ depends on time and show that for a wide class of functions with λ of the order H 3, the system of field equations leads to a stable fix-point behaviour.
TL;DR: Using N = 1 supergravity as the natural square root of gravity, the authors studied the quantum cosmology of Bianchi type I cosmological models and gave a natural interpretation of the components of the state vector of the universe.
Abstract: Using N=1 supergravity as the natural square root of gravity, the authors study the quantum cosmology of Bianchi type I cosmological models. This approach gives us a natural interpretation of the components of the state vector of the universe that was lacking in previous work on the square root of quantum cosmology.
TL;DR: According to the results, large initial fluctuations of the Higgs field do not prevent inflation, if the potential has the right shape, and a Coleman-Weinberg-type model is chosen.
Abstract: We have simulated the onset of the inflationary era of the early Universe numerically, starting with inhomogeneous initial data for the Higgs field. Our computer code is fully general relativistic, including the gravitational effect of the Higgs field, and simulates a spacetime inhomogeneous in one space direction. According to our results, large initial fluctuations of the Higgs field do not prevent inflation, if the potential has the right shape. In a Coleman-Weinberg-type model with sigma = 0.1m/sub Pl/ inflation is realized for lambdaapprox. <10/sup -2/ and with sigma = 0.01m/sub Pl/ for lambdaapprox. <10/sup -5/. .AE
TL;DR: The relation between cusp events and gamma-rays bursts is investigated in this paper, where the cosmological evolution of cosmic strings is examined, and the energetics and time-scales related to the cusp phenomena are estimated.
Abstract: The relation between cusp events and gamma-rays bursts is investigated. The optical depth of the universe to X-rays and gamma-rays of various energies is calculated and discussed. The cosmological evolution of cosmic strings is examined, and the energetics and time-scales related to the cusp phenomena are estimated. It is noted that it is possible to have energy bursts with a duration of a few seconds or less from cusps at z = 1000; the maximum amount of energy associated with such an event is limited to 10 to the 7th ergs/sq cm.
TL;DR: In this paper, it was shown that two-dimensional and timelike 'elementary' quasi-regular singularities provide a generalised version of the unusual cosmic strings. But the properties of such generalised cosmic strings are investigated and it is shown in particular that they are totally geodesic submanifolds on which the mass density mu is constant.
Abstract: It is shown that two-dimensional and timelike 'elementary' quasi-regular singularities provide a generalised version of the unusual cosmic strings. The properties of such generalised cosmic strings are investigated and it is shown in particular that they are totally geodesic submanifolds on which the mass density mu is constant.
TL;DR: In this paper, it is shown how the evolution of matter is parametrized by classical time in cosmological configurations that propagate, but behind the horizon, this time becomes imaginary.
TL;DR: In this article, an analytical model of a void, at an intermediate epoch between recombination and the present, and its gravitational influence on photons passing through it is considered, and the deviation of redshift for the photons as a function of impact parameter is calculated to lowest order.
Abstract: An analytical model of a void, at an intermediate epoch between recombination and the present, is studied, and its gravitational influence on photons passing through it is considered The background universe is a flat Friedmann-Robertson-Walker cosmology with dust The deviation of redshift for the photons as a function of impact parameter is calculated to lowest order This is used to approximate the cosmic background radiation anisotropy expected of a universe filled with such voids The temperature fluctuation with voids the size of that in Bootes is of the order 10/sup -6/ This is about two orders of magnitude lower than present published limits 31 references
TL;DR: The complete theory of the relativistic motion of a singular layer of matter under the influence of surface tension and volume tension is developed and the action functional provides a natural basis for the so-called inflationary cosmology.
Abstract: In this paper we develop the complete theory of the relativistic motion of a singular layer of matter under the influence of surface tension and volume tension. In order to account for vacuum tension effects we suggest a formalism of universal applicability: the single degree of freedom of a relativistic ``bubble'' is coupled in a gauge-invariant manner to a potential three-form A in the presence of gravity. The mathematical and physical consequences of this coupling can be summarized as follows. (i) The action functional of the theory, when written in geometric form, is formally quite similar to the Einstein-Maxwell action for the dynamics of a point charge on a Riemannian manifold. However, in comparison with electrodynamics, bubble dynamics is a highly constrained theory with a vastly different physical content: the gauge field F=dA propagates no degrees of freedom and when it is coupled to gravity alone, it gives rise to a cosmological constant of arbitrary magnitude. (ii) We exploit this peculiar property of the gauge field to solve exactly some of the equations of motion of bubble dynamics. The net physical result is the nucleation of bubbles in different ``vacuum phases'' of the de Sitter type characterized by two effective and distinct cosmological constants, one inside and one outside the domain wall. (iii) Because of the generality of the above mechanism, the theory is applicable to a variety of different physical situations; in the case of a spherical bubble we derive the radial equation of motion and solve it explicitly in a number of cases of physical interest ranging from cosmology to particle physics. Thus, in curved spacetime we find that our action functional provides a natural basis for the so-called inflationary cosmology; in flat spacetime we find that our action functional generates the same vacuum tension advocated in the so-called ``bag model'' of strong interactions in order to confine quarks and gluons.
Journal Article•
TL;DR: In this article, a cosmological model is proposed in which an inflationary de Sitter spacetime appears as the result of a fluctuation in the conformal degree of freedom of an initial Minkowski vacuum.
Abstract: A cosmological model is proposed in which an inflationary de Sitter spacetime appears as the result of a fluctuation in the conformal degree of freedom of an initial Minkowski vacuum. A population of black holes is thereby created, which evaporate during the inflationary phase. Then a second phase transition turns the de Sitter cosmology into the usual Robertson–Walker universe. The temperature and specific entropy per baryon of the present universe are deduced, and depend only on the mass of the black holes and on the universal constants h, c and k.
TL;DR: These selections from ''Le systeme du monde,\" the classic ten-volume history of the physical sciences written by the great French physicist Pierre Duhem (1861-1916), focus on cosmology, Duhem's greatest interest.
Abstract: These selections from \"Le systeme du monde,\" the classic ten-volume history of the physical sciences written by the great French physicist Pierre Duhem (1861-1916), focus on cosmology, Duhem's greatest interest. By reconsidering the work of such Arab and Christian scholars as Averroes, Avicenna, Gregory of Rimini, Albert of Saxony, Nicole Oresme, Duns Scotus, and William of Occam, Duhem demonstrated the sophistication of medieval science and cosmology.\
TL;DR: The wave function of the Universe defined by the Hartle-Hawking proposal is studied for two minisuperspace models, the Friedmann-Robertson-Walker universe with a massive scalar field and the anisotropic Kantowski-Sachs cosmology, and a comment is made on the arrow of time naturally induced by theHartle- Hawking proposal.
Abstract: The wave function of the Universe defined by the Hartle-Hawking proposal is studied for two minisuperspace models, the Friedmann-Robertson-Walker universe with a massive scalar field and the anisotropic Kantowski-Sachs cosmology. Solutions of the Wheeler-DeWitt equation are evaluated numerically. We also examine the trajectories to which these correspond in the classical limit. Attention is focused on the fact that most classical trajectories recollapse to a singularity. They will add an oscillatory component to the wave function in the region of small three-volume where it is predominantly exponential. They will thus modify the original boundary conditions. The Kantowski-Sachs universes generically evolve from isotropy during expansion to increasing anisotropy during recollapse, ending as a black-hole interior. We comment, therefore, on the arrow of time naturally induced by the Hartle-Hawking proposal.
TL;DR: The thermodynamics of superstring theories (SST-I, SST-II and heterotic string theory) and their application to the cosmology are studied in this paper.
Abstract: The thermodynamics of superstring theories (SST-I, SST-II and heterotic string theory) and its application to the cosmology are studied. The free energy of superstring gas is calculated in the one-loop approximation and the stability of the extra torus dimensions is discussed. Assuming that the Einstein equation dictates the evolution of the universe, we show that matter dominated universe filled with massive particles would never be realized at the beginning of the universe, contrary to the naive expectation in the superstring cosmology.
TL;DR: In this paper, it was shown that phase transitions which occur at the last stages of inflation may lead to the formation of exponentially large bubbles and domains containing matter with different density, which may be responsible for the observed foam-like large-scale structure of the Universe.
Abstract: It is generally assumed that primordial density perturbations necessary for galaxy formation are adiabatic perturbations with a flat (scale-independent) spectrum formed during inflation1–4. It is not clear, however, whether it is possible to create all types of large-scale structures in the Universe (quasars, galaxies, clusters, superclusters, for example) from one type of perturbation with such a simple spectrum. An alternative approach is based on the theory of cosmic strings5,6. However, it is difficult to reconcile this approach with the inflationary paradigm7. Recently it was shown that inflation may produce not only adiabatic perturbations but also isothermal perturbations7–10 with the spectra considerably different from the flat spectrum7,8,10. Moreover, phase transitions which occur at the last stages of inflation may lead to formation of exponentially large bubbles and domains containing matter with different density7. Here we demonstrate that such effects may be responsible for the observed foam-like large-scale structure of the Universe11.