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We reconsider the enhancement of primordial gravitational waves that arises from a quantum gravitational model of inflation. A distinctive feature of this model is that the end of inflation witnesses a brief phase during which the Hubble…

General Relativity and Quantum Cosmology · Physics 2015-05-30 Maria G. Romania , N. C. Tsamis , R. P. Woodard

We construct non-linear inflaton potential energy densities that describe not-necessarily very-slowly-rolling closed and open inflation models, and compute tilted primordial spatial inhomogeneity power spectra that follow from quantum…

Cosmology and Nongalactic Astrophysics · Physics 2023-01-02 Bharat Ratra

We study the predictions of anomalous inflationary models on the abundance of structures in large scale structure observations. The anomalous features encoded in primordial curvature perturbation power spectrum are (a): localized feature in…

Cosmology and Nongalactic Astrophysics · Physics 2014-12-30 Shant Baghram , Ali Akbar Abolhasani , Hassan Firouzjahi , Mohammad Hossein Namjoo

In cosmological scenarios with thermal inflation, extra eras of moduli matter domination, thermal inflation and flaton matter domination exist between primordial inflation and the radiation domination of Big Bang nucleosynthesis. During…

Cosmology and Nongalactic Astrophysics · Physics 2017-02-06 Sungwook E. Hong , Hyung-Joo Lee , Young Jae Lee , Ewan D. Stewart , Heeseung Zoe

We investigate the possibility of using future photometric and radio surveys to constrain the power spectrum of primordial fluctuations that is predicted by inflationary models with a violation of the slow-roll phase. We forecast…

Cosmology and Nongalactic Astrophysics · Physics 2018-04-17 Mario Ballardini , Fabio Finelli , Roy Maartens , Lauro Moscardini

This thesis is dedicated to studying cosmological inflation, which is a period of accelerated expansion in the very early Universe that is required to explain the observed anisotropies in the cosmic microwave background. Inflation, when…

Cosmology and Nongalactic Astrophysics · Physics 2021-02-02 Chris Pattison

We study the statistics of the primordial power spectrum in models where massless gauge vectors are coupled to the inflaton, paying special attention to observational implications of having fundamental or effective horizons embedded in a…

Cosmology and Nongalactic Astrophysics · Physics 2014-05-07 Mikjel Thorsrud , Federico R. Urban , David F. Mota

We continue the study of mild transient reductions in the speed of sound of the adiabatic mode during inflation, of their effect on the primordial power spectrum and bispectrum, and of their detectability in the Cosmic Microwave Background…

Cosmology and Nongalactic Astrophysics · Physics 2015-10-19 Ana Achucarro , Vicente Atal , Bin Hu , Pablo Ortiz , Jesus Torrado

We study the impact of the use of the power series expression for the primordial tensor spectrum on parameter estimation from future direct detection gravitational wave experiments. The spectrum approximated by the power series expansion…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-19 Sachiko Kuroyanagi , Tomo Takahashi

The simplest inflationary models predict a primordial power spectrum (PPS) of the curvature fluctuations that can be described by a power-law function that is nearly scale-invariant. It has been shown, however, that the low-multipole…

Cosmology and Nongalactic Astrophysics · Physics 2016-05-25 Eleonora Di Valentino , Stefano Gariazzo , Martina Gerbino , Elena Giusarma , Olga Mena

The conventional slow-roll approximation is broken in the so-called "ultra slow-roll" models of inflation, for which the inflaton potential is exactly (or extremely) flat. The interesting nature of (canonical) ultra slow-roll inflation is…

Cosmology and Nongalactic Astrophysics · Physics 2016-11-18 Shin'ichi Hirano , Tsutomu Kobayashi , Shuichiro Yokoyama

The next generation of space-borne gravitational wave detectors may detect gravitational waves from extreme mass-ratio inspirals with primordial black holes. To produce primordial black holes which contribute a non-negligible abundance of…

Cosmology and Nongalactic Astrophysics · Physics 2018-07-04 Haoran Di , Yungui Gong

There is a large and growing interest in observations of small-scale structure in dark matter. We propose a new way to probe dark matter structures in the $\sim 10 - 10^8 \, M_\odot$ range. This allows us to constrain the primordial power…

High Energy Physics - Phenomenology · Physics 2024-10-17 Peter W. Graham , Harikrishnan Ramani

We discuss how primordial (e.g. inflationary) non-Gaussianity in the cosmological perturbations is left imprinted in the Large-Scale Structure of the universe. Our findings show that the information on the primordial non-Gaussianity set on…

Astrophysics · Physics 2009-11-10 N. Bartolo , S. Matarrese , A. Riotto

The gravitationally enhanced friction can reduce the speed of the inflaton to realize an ultra-slow-roll inflation, which will amplify the curvature perturbations. The amplified perturbations can generate a sizable amount of primordial…

General Relativity and Quantum Cosmology · Physics 2022-10-27 Li-Yang Chen , Hongwei Yu , Puxun Wu

We study the non-linear dynamics of axion inflation, capturing for the first time the inhomogeneity and full dynamical range during strong backreaction, till the end of inflation. Accounting for inhomogeneous effects leads to a number of…

Cosmology and Nongalactic Astrophysics · Physics 2023-05-01 Daniel G. Figueroa , Joanes Lizarraga , Ander Urio , Jon Urrestilla

We present a minimally parametric, model independent reconstruction of the shape of the primordial power spectrum. Our smoothing spline technique is well-suited to search for smooth features such as deviations from scale invariance, and…

Cosmology and Nongalactic Astrophysics · Physics 2016-08-24 Andrea Ravenni , Licia Verde , Antonio J. Cuesta

The large-scale power deficit in the cosmic microwave background fluctuations might be relevant with the physics of pre-inflation, a bounce, or a superinflationary phase preceding slow-roll inflation, which can provide a singular-free…

Cosmology and Nongalactic Astrophysics · Physics 2015-07-15 Yong Cai , Yu-Tong Wang , Yun-Song Piao

A macroscopic universe may emerge naturally from a Planck cell fluctuation by unfolding through a stage of exponential expansion towards a homogeneous cosmological background. Such primordial inflation requires a large and presumably…

High Energy Physics - Theory · Physics 2007-05-23 F. Englert

We compute the power spectrum of curvature perturbations in stochastic inflation. This combines the distribution of first crossing times through the end-of-inflation surface, which has been previously studied, with the distribution of the…

Cosmology and Nongalactic Astrophysics · Physics 2021-04-27 Kenta Ando , Vincent Vennin