Related papers: New Frontiers in Cosmology and Galaxy Formation: C…
For a few years now, cosmology has a standard model. By this term, we mean a consistent theoretical background which is at the same time simple and broad enough to offer coherent explanations for the vast majority of cosmological phenomena.…
Cosmology is undergoing an explosive period of activity, fueled both by new, accurate astrophysical data and by innovative theoretical developments. Cosmological parameters such as the total density of the Universe and the rate of…
The standard model of cosmology considers the existence of two components of unknown nature, ``dark matter'' and ``dark energy'', which determine the cosmological evolution. Their nature remains unknown, and other models can also be…
The discovery of the accelerating universe in the late 1990s was a watershed moment in modern cosmology, as it indicated the presence of a fundamentally new, dominant contribution to the energy budget of the universe. Evidence for dark…
In this Essay we address several fundamental issues in cosmology: What is the nature of dark energy and dark matter? Why is the dark sector so different from ordinary matter? Why is the effective cosmological constant non-zero but so…
The discovery ten years ago that the expansion of the Universe is accelerating put in place the last major building block of the present cosmological model, in which the Universe is composed of 4% baryons, 20% dark matter, and 76% dark…
A cosmology is considered driven by a stress-energy tensor consisting of a perfect fluid, an inhomogeneous pressure term (which we call a ``tachyonic dust'' for reasons which will become apparent) and a cosmological constant. The…
The formation of the first stars and quasars marks the transformation of the universe from its smooth initial state to its clumpy current state. In popular cosmological models, the first sources of light began to form at redshift 30 and…
The elegance of inflationary cosmology and cosmological perturbation theory ends with the formation of the first stars and galaxies, the initial sources of light that launched the phenomenologically rich process of cosmic reionization. Here…
We consider two problems that have vexed physicists for several decades -- dark matter and the cosmological constant. The problem has been that the former has not been detected while the latter gives a far higher value than detected by…
There is now strong evidence that the current energy density of the Universe is dominated by dark energy with an equation of state w<-1/3, which is causing accelerated expansion. The build-up of structure within such Universes is subject to…
In these lectures I examine some of the principal issues in cosmology from a particle physics point of view. I begin with nucleosynthesis and show how the primordial abundance of the light elements can help fix the number of (light)…
(Abridged) Present cosmological constraints and the absence of a direct detection and identification of any dark matter particle candidate leave room to the possibility that the dark sector of the Universe be actually more complex than it…
The study of formation and evolution of galaxies is reviewed, making emphasis on the physical factors which are important to understand the origin of the galaxy Hubble sequence. We concentrate on predictions of the hierarchical Cold Dark…
The standard cosmological paradigm currently lacks a detailed account of physics in the dark sector, the dark matter and energy that dominate cosmic evolution. In this paper, we consider the distinguishing factors between three alternative…
Progress in observational cosmology over the past five years has established that the Universe is dominated dynamically by dark matter and dark energy. Both these new and apparently independent forms of matter-energy have properties that…
This essay is a nontechnical primer for a broader audience, in which I paint a broad-brush picture of modern cosmology. I begin by reviewing the evidence for the big bang, including the expansion of our Universe, the cosmic microwave…
Several problems in cosmology and astrophysics are described in which critical phenomena of various types may play a role. These include the organization of the disks of spiral galaxies, various aspects of the problem of structure formation…
While the generally recognized symmetries of cosmos are preserved, conservation laws for gravitational system are reconsidered and the Lagrangian density of pure gravitational field is revised. From these considerations, some of the…
We present a new scenario for the development of the Universe after the Big Bang, built on the conjecture that a vast majority of the primordial quark matter did not undergo a phase transition to normal nuclear matter, but rather split up…