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We investigate density perturbations sourced by a curvaton with a generic energy potential. The key feature of a curvaton potential which deviates from a quadratic is that the curvaton experiences a non-uniform onset of its oscillation.…

Cosmology and Nongalactic Astrophysics · Physics 2011-12-12 Masahiro Kawasaki , Takeshi Kobayashi , Fuminobu Takahashi

We give new constraints on small-scale non-Gaussianity of primordial curvature perturbations by the use of anisotropies in acoustic reheating. Mixing of local thermal or local kinetic equilibrium systems with different temperatures yields a…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Atsushi Naruko , Atsuhisa Ota , Masahide Yamaguchi

It is known that stochastic gravitational wave backgrounds (SGWBs) have anisotropies generated by squeezed-type tensor non-Gaussianities originating from scalar-tensor-tensor (STT) and tensor-tensor-tensor cubic interactions. While the…

Cosmology and Nongalactic Astrophysics · Physics 2025-12-01 Shingo Akama , Shin'ichi Hirano , Shuichiro Yokoyama

If more than one curvaton dominate the Universe at different epochs from each other, curvature perturbations can be temporarily enhanced to a value much larger than the observed one 10^{-5}. The traces of the enhancement may be left as…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-29 Teruaki Suyama , Jun'ichi Yokoyama

Building on the recent lattice simulations of ultra-slow-roll (USR) dynamics presented in arXiv:2410.23942, we investigate the role of the nonlinear relation between the inflaton field configuration and the curvature perturbation $\zeta$,…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-08 Angelo Caravano , Gabriele Franciolini , Sébastien Renaux-Petel

Primordial black holes represent a unique probe to constrain the early universe on small scales - providing the only constraints on the primordial power spectrum on the majority of scales. However, these constraints are strongly dependent…

Cosmology and Nongalactic Astrophysics · Physics 2016-02-17 Sam Young , Donough Regan , Christian T. Byrnes

We provide a dynamical mechanism to generate localized features during inflation. The local feature is due to a sharp waterfall phase transition which is coupled to the inflaton field. The key effect is the contributions of waterfall…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Ali Akbar Abolhasani , Hassan Firouzjahi , Shahram Khosravi , Misao Sasaki

We consider an alternative approach for the computation of the stochastic gravitational wave background generated by small loops produced throughout the cosmological evolution of cosmic string networks and use it to derive an analytical…

Cosmology and Nongalactic Astrophysics · Physics 2016-10-05 L. Sousa , P. P. Avelino

Cosmological solitons are widely predicted by scenarios of the early Universe. In this work, we investigate the isotropic background and anisotropies of gravitational waves (GWs) induced by soliton isocurvature perturbations, especially…

Cosmology and Nongalactic Astrophysics · Physics 2025-04-04 Di Luo , Yan-Heng Yu , Jun-Peng Li , Sai Wang

We present an estimate for the non-linear parameter \tau_NL, which measures the non-gaussianity imprinted in the trispectrum of the comoving curvature perturbation, \zeta. Our estimate is valid throughout the inflationary era, until the…

Astrophysics · Physics 2010-10-27 David Seery , James E. Lidsey

First-order primordial curvature perturbations are known to induce gravitational waves at the second-order, which can in turn probe the small-scale curvature perturbations near the end of the inflation. In this work, we extend the previous…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-21 Xiang-Xi Zeng , Rong-Gen Cai , Shao-Jiang Wang

We analyze the shape and amplitude of oscillatory features in the primordial power spectrum and non-Gaussianity induced by periodic production of heavy degrees of freedom coupled to the inflaton $\phi$. We find that non-adiabatic production…

High Energy Physics - Theory · Physics 2017-11-15 Raphael Flauger , Mehrdad Mirbabayi , Leonardo Senatore , Eva Silverstein

We study the dependence on configuration in momentum space of the primordial 3-point function of density perturbations in several different scenarios: standard slow-roll inflation, curvaton and variable decay models, ghost inflation, models…

Astrophysics · Physics 2009-07-09 Daniel Babich , Paolo Creminelli , Matias Zaldarriaga

In this review, we discuss how non-Gaussianity of cosmological perturbations arises from inflation. After introducing the in-in formalism to calculate the $n$-point correlation function of quantum fields, we present the computation of the…

High Energy Physics - Theory · Physics 2014-11-20 Kazuya Koyama

The bispectrum is the lowest-order statistic sensitive to the shape of structures generated by gravitational instability and is a potentially powerful probe of galaxy biasing and the Gaussianity of primordial fluctuations. Although the…

Astrophysics · Physics 2009-10-31 Roman Scoccimarro

The primary science driver for 3D galaxy surveys is their potential to constrain cosmological parameters. Forecasts of these surveys' effectiveness typically assume Gaussian statistics for the underlying matter density, despite the fact…

Cosmology and Nongalactic Astrophysics · Physics 2015-10-27 Andrew Repp , István Szapudi , Julien Carron , Melody Wolk

In the next decade gravitational waves might be detected using a pulsar timing array. In an effort to develop optimal detection strategies for stochastic backgrounds of gravitational waves in generic metric theories of gravity, we…

High Energy Astrophysical Phenomena · Physics 2013-05-30 Sydney J. Chamberlin , Xavier Siemens

We study cosmological tensor perturbations induced by second-order scalar perturbations in the presence of anisotropic non-Gaussianity. This class of induced tensor modes arises on superhorizon scales through the intrinsic quadrupole…

Cosmology and Nongalactic Astrophysics · Physics 2020-05-13 Atsuhisa Ota

The microscopic dynamics of particle collisions is imprinted into the statistical properties of asymptotic energy flux, much like the dynamics of inflation is imprinted into the cosmic microwave background. This energy flux is characterized…

High Energy Physics - Phenomenology · Physics 2022-08-24 Hao Chen , Ian Moult , Jesse Thaler , Hua Xing Zhu

The normalisation of the matter power spectrum, sigma_8, is an essential ingredient to predict the phenomenology of the low redshift universe. It has been measured using several methods, such as X-ray cluster counts, weak lensing and the…

Astrophysics · Physics 2008-11-26 A. Amara , A. Refregier