Related papers: Probing Inflation and Dark Energy with Current Cos…
In the theories described by a volume normalized action functional, an arbitrary cosmological constant is eliminated from the physical picture of our Universe, and dynamical alternatives must be responsible for today's accelerated expansion…
We consider a k-essence model in which a single scalar field can be responsible for both primordial inflation and the present observed acceleration of the cosmological background geometry, while also admitting a nonsingular de Sitter…
Alan Guth introduced cosmologists to inflation at the 1980 Texas Symposium. Since, inflation has had almost as much impact on cosmology as the big-bang model itself. However, unlike the big-bang model, it has little observational support.…
A simple speed-up cosmology model is proposed to account for the dark energy puzzle. We condense contributions from dark energy and curvature term into one effective parameter in order to reduce parameter degeneracies and to find any…
The cause for the observed acceleration in the expansion of the universe is unknown, and referred to as "dark energy" for convenience. Dark energy could be an unknown energy component, or a modification of Einstein's general relativity.…
A better understanding of the formation of large-scale structure in the Universe is arguably the most pressing question in cosmology. The most compelling and promising theoretical paradigm, Inflation + Cold Dark Matter, holds that the…
In the hope of avoiding model dependence of the cosmological observables, phenomenological parametrizations of Cosmic Inflation have recently been proposed. Typically, they are expressed in terms of two parameters associated with an…
In the present paper, it is found that dark energy emerges spontaneously from the modified gravity. According to cosmological scenario, obtained here, the universe inflates for $\sim 10^{-37}$ sec. in the beginning and late universe…
We work out an effective theory of accelerated expansion to describe general phenomena of inflation and acceleration (dark energy) in the Universe. Our aim is to determine from theoretical grounds, in a physically-motivated and model…
I present a pedagogical review of inflation and the cosmic microwave background. I describe how a short period of accelerated expansion can replace the special initial conditions of the standard big bang model. I also describe the…
A new cosmic scenario with gravitationally induced particle creation is proposed. In this model the Universe evolves from an early to a late time de Sitter era, with the recent accelerating phase driven only by the negative creation…
It is proposed that after the macroscopic fluctuation of energy density that is responsible for inflation dies away, a class of microscopic fluctuations, always present, survives to give the present day dark energy. This latter is simply a…
In a previous paper we proposed a new approach to the beginning of inflation -- a lingering universe. The universe begins in a lingering state with a nearly vanishing Hubble parameter. This calls into question the absolute age of the…
We consider an inflationary universe scenario with multiple stages of inflation. The primary inflation, which may start at the Planck epoch, is followed by secondary inflations, which include the cosmological inflation that causes the…
Recent large scale structure observations, including COBE, have prompted many authors to discuss modifications of the standard Cold Dark Matter model. Two of these, a tilted spectrum and a gravitational wave contribution to COBE, are at…
Cosmology is very exciting for three reasons. There is a very successful standard model - the hot big bang - which describes the evolution of the Universe from 10^{-2} sec onward. There are bold ideas, foremost among them are inflation and…
A web of interlocking observations has established that the expansion of the Universe is speeding up and not slowing, revealing the presence of some form of repulsive gravity. Within the context of general relativity the cause of cosmic…
We construct an explicit scenario whereby the same material driving inflation in the early Universe can comprise dark matter in the present Universe, using a simple quadratic potential. Following inflation and preheating, the density of…
The inflationary and pre-inflationary evolution of scalar modes of cosmological perturbations in a closed universe is analyzed for a loop quantum cosmology model with an inflationary regime consistent with the constraints on inflation…
The evolution of a scalar field is explored taking into account the presence of a background fluid in a positively curved Universe in the framework of loop quantum cosmology. Though the mechanism that provides the initial conditions for…