相关论文: Relic gravitons from super-inflation
According to the most popular scenario, the early Universe should have experienced an accelerated expansion phase, called Cosmological Inflation, after which the standard Big Bang Cosmology would have taken place giving rise to the…
Using a large N sigma model approximation we explicitly calculate the power spectrum of gravitational waves arising from a global phase transition in the early universe and we confirm that it is scale invariant, implying an observation of…
In a recent paper, which has been published in Nature, the LIGO Scientific Collaboration (LSC) obtained an upper limit on the stochastic gravitational-wave background of cosmological origin by using the data from a two-year science run of…
We discuss the effects of cosmic phase transition on the spectrum of primordial gravitational waves generated during inflation. The energy density of the scalar condensation responsible for the phase transition may become sizable at the…
In loop quantum cosmology, the universe avoids a big bang singularity and undergoes an early and short super-inflation phase. During super-inflation, non-perturbative quantum corrections to the dynamics drive an inflaton field up its…
We investigate the dependence of the gravitational wave spectrum from quintessential inflation on the reheating process. We consider two extreme reheating processes. One is the gravitational reheating by particle creation in the expanding…
We investigate the production of gravitational waves during preheating after inflation in the common case of field potentials that are asymmetric around the minimum. In particular, we study the impact of oscillons, comparatively long lived…
We investigate the dynamics of super-inflation in two versions of Loop Quantum Cosmology, one in which the Friedmann equation is modified by the presence of inverse volume corrections, and one in which quadratic corrections are important.…
The energy spectra of gravitational waves (GW) produced in quintessential inflationary models increase in frequency and exhibit a sharp spike around 170 GHz where the associated fraction of critical energy density today stored in relic…
The reheating of the universe after hybrid inflation proceeds through the nucleation and subsequent collision of large concentrations of energy density in the form of bubble-like structures moving at relativistic speeds. This generates a…
We discuss the implications of purely classical, instead of quantum, theory of gravity for the gravitational wave spectrum generated during inflation. We show that a positive detection of primordial gravitational waves will no longer…
Loop quantum cosmology allows to replace the original singularity by a quantum bounce followed by a phase of fast expansion called super-inflation. In this paper, we use a simple analytic description of super-inflation using the equation of…
In many models of inflation, the period of accelerated expansion ends with preheating, a highly non-thermal phase of evolution during which the inflaton pumps energy into a specific set of momentum modes of field(s) to which it is coupled.…
We consider gravitational wave production due to parametric resonance at the end of inflation, or ``preheating''. This leads to large inhomogeneities which source a stochastic background of gravitational waves at scales inside the comoving…
The continual production of gravitons during inflation endows loop corrections with secular logarithms which grow nonperturbatively large during a prolonged period of inflation. The physics behind these effects is reviewed, along with a…
The early expansion history of the Universe is constrained by combining the most recent limits on the cosmic gravitons in the audio band and the claimed evidences of the nHz domain. The simplest scenario stipulates that between the end of…
Reheating after inflation can proceed even if the inflaton couples to Standard Model (SM) particles only gravitationally. However, particle production during the transition between de-Sitter expansion and a decelerating Universe is rather…
In this work, we systematically study gravitational wave (GW) production during both the inflationary and post-inflationary epochs. While inflationary GWs can be readily derived from tensor perturbations during inflation, post-inflationary…
The inflationary paradigm is an important cornerstone of the concordance cosmological model. However, standard inflation cannot fully address the transition from an early homogeneous and isotropic stage, to another one lacking such…
Using techniques from loop quantum gravity, the standard theory of cosmological perturbations was recently generalized to encompass the Planck era. We now apply this framework to explore pre-inflationary dynamics. The framework enables us…