Related papers: Gravitational Waves from Incomplete Inflationary P…
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…
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…
We study gravitational-wave production from bubble dynamics (bubble collisions and sound waves) during a cosmic first-order phase transition with an analytic approach. We first propose modeling the system with the thin-wall approximation…
Whether or not the primordial gravitational wave (GW) produced during inflation is sufficiently strong to be observable, GWs are necessarily produced from the primordial curvature perturbations in the second order of perturbation. The…
In a variety of inflation models the motion of the inflaton may trigger the production of some non-inflaton particles during inflation, for example via parametric resonance or a phase transition. Particle production during inflation leads…
First-order phase transitions in the early Universe are a well-motivated source of gravitational waves (GWs). In this Letter, we identify a previously overlooked GW production mechanism: gravitational transition radiation, arising from…
There is a growing expectation that the gravitational wave detectors will start probing the stochastic gravitational wave backgrounds in the following years. We explore the spectral shapes of gravitational waves induced to second order by…
Inflation produces a primordial spectrum of gravity waves in addition to the density perturbations which seed structure formation. We compute the signature of these gravity waves in the large scale shear field. In particular, the shear can…
A pseudoscalar inflaton $\varphi$, coupled to the topological charge density $F\tilde{F}$ of a non-Abelian sector, can decay to gauge bosons ($\varphi\to g g $), which may thermalize rapidly. The friction felt by $\varphi$ is then increased…
We investigate the production of a stochastic background of gravitational waves in the electroweak phase transition. We consider extensions of the Standard Model which can give very strongly first-order phase transitions, such that the…
Curvature perturbations generated after the end of inflation are estimated for a generic multi-field inflationary potential. The curvature perturbations are generated by conversion of inflationary isocurvature perturbations, similar to…
The detection of a stochastic Gravitational Wave (GW) background sourced by a cosmological phase transition would allow us to see the early Universe from a completely new perspective, illuminating aspects of Beyond the Standard Model (BSM)…
In the context of the open inflationary universe, we calculate the amplitude of quantum fluctuations which deform the bubble shape. These give rise to scalar field fluctuations in the open Friedman-Robertson-Walker universe which is…
We investigate the production of gravitational waves due to quantum fluctuations of the vacuum during the transition from the inflationary to the radiation-dominated eras of the universe, assuming this transition to be dominated by the…
A short introduction to structure formation is given, followed by a discussion of the possible characteristics of the initial perturbations assuming a generic inflationary origin. Observational data related to large-scale structure and the…
The curvaton scenario for the generation of the cosmological curvature perturbation on large scales represents an alternative to the standard slow-roll scenario of inflation in which the observed density perturbations are due to…
Gravitational waves have become an irreplaceable tool for exploring the post-inflationary universe. Their cosmological and astrophysical origins have been attracting numerous attention. In this Letter, we point out a novel source of…
Primordial gravitational waves are amplified during eras when their wavelengths are pushed outside the cosmological horizon. This occurs in both inflationary and ``pre-big-bang'' or ``bounce'' cosmologies. The spectrum is expressed as a…
We discuss a cosmological scenario with a stochastic background of gravitational waves sourced by the tensor perturbation due to a hybrid inflationary model with cubic potential. The tensor-to-scalar ratio for the present hybrid…
Assuming that inflation is followed by a phase where the energy density of the Universe is dominated by a component with a general equation of state, we evaluate the spectrum of primordial gravitational waves induced in the…