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The COBE satellite's maps of the cosmic microwave background (CMB) anisotropy do not have the resolution to discriminate between theories of cosmic structure formation based on inflation, and those based on field ordering following a…

High Energy Physics - Phenomenology · Physics 2009-09-25 David Coulson , Ue-Li Pen , Neil Turok

We investigate the question whether small quantum-gravitational effects can be observed in the anisotropy spectrum of the cosmic microwave background radiation. An observation of such an effect is needed in order to discriminate between…

General Relativity and Quantum Cosmology · Physics 2012-10-15 Claus Kiefer , Manuel Kraemer

Inflationary cosmology provides a natural mechanism for the generation of primordial perturbations which seed the formation of observed cosmic structure and lead to specific signals of anisotropy in the cosmic microwave background…

Astrophysics · Physics 2011-07-19 Salman Habib , Andreas Heinen , Katrin Heitmann , Gerard Jungman

The evolution of scale-invariant gravity waves from the early universe is analyzed using an equation of state which smoothly interpolates between the radiation dominated era and the present matter dominated era. We find that for large…

Astrophysics · Physics 2009-10-22 K. -W. Ng , A. D. Speliotopoulos

Temperature anisotropy of the cosmic microwave background offers a test of the fundamental symmetry of spacetime during cosmic inflation. Violation of rotational symmetry yields a distinct signature in the power spectrum of primordial…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-04 Jaiseung Kim , Eiichiro Komatsu

Inflationary cosmology proposes that the early Universe undergoes accelerated expansion, driven, in simple scenarios, by a single scalar field, or inflaton. The form of the inflaton potential determines the initial spectra of density…

Cosmology and Nongalactic Astrophysics · Physics 2022-09-21 Richard Easther , Benedict Bahr-Kalus , David Parkinson

Recent measurements of the Cosmic Microwave Background Anisotropy have provided evidence for the presence of oscillations in the angular power spectrum. These oscillations are a wonderful confirmation of the standard cosmological scenario…

Astrophysics · Physics 2007-05-23 Alessandro Melchiorri

The anisotropy of the cosmic microwave background radiation contains information about the contents and history of the universe. We report new limits on cosmological parameters derived from the angular power spectrum measured in the first…

Most of the analysis of the Cosmic Microwave Background relies on the assumption of statistical isotropy. However, given some recent evidence pointing against isotropy, as for instance the observed alignment of different multipoles on large…

Astrophysics · Physics 2007-11-12 A. E. Gumrukcuoglu , Carlo R. Contaldi , Marco Peloso

Parametric resonance in a single-field inflationary model with a periodic structure on the potential gives rise to curvature perturbations with large amplitudes on small scales, which could result in observable primordial black holes (PBHs)…

Cosmology and Nongalactic Astrophysics · Physics 2023-01-02 Zhi-Zhang Peng , Chengjie Fu , Jing Liu , Zong-Kuan Guo , Rong-Gen Cai

We investigate the gravitational-wave background predicted by a two-scalar-field cosmological model that aims to unify primordial inflation with the dark sector, namely late-time dark energy and dark matter, in a single and self-consistent…

General Relativity and Quantum Cosmology · Physics 2026-02-05 Orlando Luongo , Tommaso Mengoni , Paulo M. Sá

Recent observations opened up a new window on the inflationary model building. As it was firstly reported by the WMAP data, there may be some indications of statistical anisotropy on the CMB map, although the statistical significance of…

Cosmology and Nongalactic Astrophysics · Physics 2015-11-06 Razieh Emami

Boomerang, Maxima, DASI, CBI and VSA significantly increase the case for accelerated expansion in the early universe (the inflationary paradigm) and at the current epoch (dark energy dominance), especially when combined with data on high…

It is widely accepted that the primordial universe experienced a brief period of accelerated expansion called inflation. This scenario provides a plausible solution to the horizon and flatness problems. However, the particle physics…

General Relativity and Quantum Cosmology · Physics 2020-07-17 Sebastien Galtier , Jason Laurie , Sergey V. Nazarenko

We supply fitting formulae enabling the normalization of slow-roll inflation models to the four-year COBE data. We fully include the effect of the gravitational wave modes, including the predicted relation of the amplitude of these modes to…

Astrophysics · Physics 2008-11-26 Emory F Bunn , Andrew R Liddle , Martin White

We show that during cosmological inflation the nonsymmetric metric tensor theory of gravitation develops a spectrum which is potentially observable by cosmic microwave background observations, and may be the most sensitive probe of the…

Astrophysics · Physics 2007-05-23 Tomislav Prokopec , Wessel Valkenburg

We investigate the anisotropies of the stochastic gravitational-wave background (SGWB) produced by cosmic strings associated with the spontaneous U(1) symmetry breaking of Grand Unified Theory, which happens at the onset of inflation. The…

Cosmology and Nongalactic Astrophysics · Physics 2021-12-21 Rong-Gen Cai , Zong-Kuan Guo , Jing Liu

This article provides an introductory review of inflation and cosmological perturbation theory. I begin by motivating the need for an epoch of inflation during the early stages of the radiation dominated era, and describe how inflation is…

Cosmology and Nongalactic Astrophysics · Physics 2024-07-08 L. Sriramkumar

Near comoving wavenumber k, the gravitational-wave background (GWB) from inflation carries information about the physical conditions near two moments in cosmic history: the moment when k ``left the horizon'' during inflation, and the moment…

Astrophysics · Physics 2008-11-26 Latham A. Boyle , Paul J. Steinhardt

The study of anisotropies in the Cosmic Microwave Background radiation is progressing at a phenomenal rate, both experimentally and theoretically. These anisotropies can teach us an enormous amount about the way that fluctuations were…

Astrophysics · Physics 2008-11-26 Douglas Scott , Martin White