Imprint of gravitational waves in models dominated by a dynamical cosmic scalar field

The aim of this research is to use modern techniques in scalar ﬁeld Cosmol-ogy to produce methods of detecting gravitational waves and apply them to current gravitational waves experiments and those that will be producing results in the not too distant future. In the ﬁrst chapter we discuss dark matter and some of its candidates, speciﬁcally, the axion. We then address its relationship with gravitational waves. We also discuss inﬂation and how it can be used to detect gravitational waves. Chapter 2 concentrates on constructing a multi ﬁeld system of axions in order to increase the mass range of the ultralight axion, putting it into the observation range of pul-sar timing arrays. Chapter 3 discusses non-attractor inﬂation which is able to enhance stochastic background gravitational waves at scales that allows them to be measured by gravitational wave experiments. Chapter 4 uses a similar method to chapter 3 and applies it to 3-point overlap functions for tensor, scalar and a combination of the two polarisations.

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The investigation of detectability of the relic gravitational waves based on the WMAP-9 and Planck

International Journal of Modern Physics D ◽

10.1142/s0218271817500031 ◽

2017 ◽

Vol 26 (02) ◽

pp. 1750003 ◽

Cited By ~ 2

Author(s):

Basem Ghayour

Keyword(s):

Scalar Field ◽

Gravitational Waves ◽

Crucial Role ◽

Planck Data ◽

Evolution Of The Universe ◽

Cosmological Observations ◽

Relic Gravitational Waves ◽

The Waves ◽

The Universe ◽

General Range

The generated relic gravitational waves underwent several stages of evolution of the universe such as inflation and reheating. These stages were affected on the shape of spectrum of the waves. As well known, at the end of inflation, the scalar field [Formula: see text] oscillates quickly around some point where potential [Formula: see text] has a minimum. The end of inflation stage played a crucial role on the further evolution stages of the universe because particles were created and collisions of the created particles were responsible for reheating the universe. There is a general range for the frequency of the spectrum [Formula: see text])[Formula: see text]Hz. It is shown that the reheating temperature can affect on the frequency of the spectrum as well. There is constraint on the temperature from cosmological observations based on WMAP-9 and Planck. Therefore, it is interesting to estimate allowed value of frequencies of the spectrum based on general range of reheating temperature like few MeV [Formula: see text] GeV, WMAP-9 and Planck data then compare the spectrum with sensitivity of future detectors such as LISA, BBO and ultimate-DECIGIO. The obtained results of this comparison give us some more chance for detection of the relic gravitational waves.

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SPECTRA OF RELIC GRAVITONS AND BRANS–DICKE THEORY

Modern Physics Letters A ◽

10.1142/s0217732305015501 ◽

2005 ◽

Vol 20 (02) ◽

pp. 127-134 ◽

Cited By ~ 1

Author(s):

B. K. SAHOO

Keyword(s):

Scalar Field ◽

Energy Density ◽

Time Dependence ◽

Gravitational Waves ◽

Hubble Parameter ◽

Frequency Dependent ◽

Cosmological Expansion ◽

Relic Gravitational Waves ◽

Matter Energy ◽

Inflationary Models

The spectra of relic gravitational waves produced as a result of cosmological expansion of the inflationary models are derived in Brans–Dicke (BD) theory of gravity. The time dependence of the very early Hubble parameter and matter energy density are derived from frequency-dependent spectrum of relic gravitational waves. Also it is found that Brans–Dicke scalar field contributes to the energy density of relic gravitons.

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Large-scale magnetic fields, non-Gaussianity, and gravitational waves from inflation

International Journal of Modern Physics A ◽

10.1142/s0217751x17470212 ◽

2017 ◽

Vol 32 (36) ◽

pp. 1747021

Author(s):

Kazuharu Bamba

Keyword(s):

Scalar Field ◽

Magnetic Fields ◽

Gravitational Waves ◽

Electromagnetic Fields ◽

Conformal Invariance ◽

Large Scale ◽

Gauge Fields ◽

Density Perturbations ◽

Hubble Horizon

We explore the generation of large-scale magnetic fields in the so-called moduli inflation. The hypercharge electromagnetic fields couple to not only a scalar field but also a pseudoscalar one, so that the conformal invariance of the hypercharge electromagnetic fields can be broken. We explicitly analyze the strength of the magnetic fields on the Hubble horizon scale at the present time, the local non-Gaussianity of the curvature perturbations originating from the massive gauge fields, and the tensor-to-scalar ratio of the density perturbations. As a consequence, we find that the local non-Gaussianity and the tensor-to-scalar ratio are compatible with the recent Planck results.

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Review of the possible role of self-ordering scalar fields in production of a stochastic background of gravitational waves

International Journal of Modern Physics D ◽

10.1142/s0218271815410059 ◽

2015 ◽

Vol 24 (04) ◽

pp. 1541005

Author(s):

James B. Dent

Keyword(s):

Phase Transition ◽

Scalar Field ◽

Gravitational Wave ◽

Gravitational Waves ◽

Scalar Fields ◽

Inflationary Cosmology ◽

Tensor Power ◽

Stochastic Background ◽

Gravitational Wave Background

A primordial gravitational wave background is a hallmark of inflationary cosmology. The recent announcement made by the BICEP2 collaboration of a possible measurement of B-mode polarization of the CMB on degree scales has produced an abundance of ideas and speculations on how such a signal constrains the inflationary paradigm, or possible alternative mechanisms of gravitational wave production. Here the possibility of a contribution to the gravitational wave background from the relaxation of a scalar field after a global phase transition is reviewed. The general contribution to the overall power is shown, and it is then demonstrated that if the BICEP2 result were to hold, this mechanism could at best produce a very small fraction of the measured tensor power.

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Some Remarks on Gravitational Interaction and Gravitational Waves

Zeitschrift für Naturforschung A ◽

10.1515/zna-1965-0401 ◽

1965 ◽

Vol 20 (4) ◽

pp. 495-497

Author(s):

G. Braunss

Keyword(s):

Scalar Field ◽

Gravitational Wave ◽

Gravitational Waves ◽

Nonlinear Theory ◽

Strong Interaction ◽

Spinor Field ◽

Gravitational Interaction ◽

Metric Tensor ◽

Free Wave

A brief consideration of the problem of gravitational waves is given on the basis of the following assumption: The components of the metric tensor are functionals of a field by which, in the sense of HEISENBERG’S nonlinear theory, all other fields resp. the corresponding interactions can be deduced. For the sake of mathematical simplicity a scalar field Φ (noncharged bosons) is considered instead of a spinor field. The condition gmn=gmn (Φ) resp. Rmn = Rmn (Φ) leads to the statement that the concept of a free gravitational wave, i. e. a wave which is a solution of Rmn=0 or Rklmn = 0, cannot be accepted. A free wave is here by definition a wave which is so far from the origin that one can neglect in the field eqs. all terms which represent a strong interaction. A comparison with a spinor field leads, with regard to this definition, to the conclusion that a free wave may be considered as a neutrino wave and gravitation as the weakest interaction possible of neutrino fields.

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Gravitational waves from scalar field accretion

Physical Review D ◽

10.1103/physrevd.84.024043 ◽

2011 ◽

Vol 84 (2) ◽

Cited By ~ 6

Author(s):

Darío Núñez ◽

Juan Carlos Degollado ◽

Claudia Moreno

Keyword(s):

Scalar Field ◽

Gravitational Waves

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FLUCTUATION SPECTRUM FROM A SCALAR-TENSOR BIMETRIC GRAVITY THEORY

International Journal of Modern Physics D ◽

10.1142/s0218271803003098 ◽

2003 ◽

Vol 12 (04) ◽

pp. 697-712 ◽

Cited By ~ 6

Author(s):

M. A. CLAYTON ◽

J. W. MOFFAT

Keyword(s):

Scalar Field ◽

Gravitational Waves ◽

Early Universe ◽

Initial Period ◽

Field Potential ◽

Gravity Theory ◽

Fluctuation Spectrum ◽

Quadratic Potential ◽

Initial Values ◽

Bimetric Gravity

Predictions of the CMB spectrum from a bimetric gravity theory (BGT)1 are presented. The initial inflationary period in BGT is driven by a vanishingly small speed of gravitational waves vg in the very early universe. This initial inflationary period is insensitive to the choice of scalar field potential and initial values of the scalar field. After this initial period of inflation, vg will increase rapidly and the effects of a potential will become important. We show that a quadratic potential introduced into BGT yields an approximately flat spectrum with inflation parameters: ns=0.98, nt=-0.027, αs=-3.2×10-4 and αt=-5.0×10-4, with r ≥ 0.014.

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QUANTUM FLUCTUATIONS FOR A SCALAR FIELD IN THE SPACE–TIME OF GRAVITATIONAL IMPLUSIVE WAVE

International Journal of Modern Physics A ◽

10.1142/s0217751x9800055x ◽

1998 ◽

Vol 13 (08) ◽

pp. 1201-1211 ◽

Cited By ~ 1

Author(s):

Y. ENGINER ◽

M. HORTAÇSU ◽

N. ÖZDEMIR

Keyword(s):

Scalar Field ◽

Gravitational Waves ◽

Quantum Fluctuations ◽

De Sitter Space ◽

Space Time ◽

Massless Scalar ◽

Massless Scalar Field ◽

De Sitter

Quantum fluctuations for a massless scalar field in the background metric of spherical implusive gravitational waves propagating through Minkowski and de Sitter spaces are investigated. It is shown that there exist finite fluctuations for de Sitter space.

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