Curvaton

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The curvaton is a hypothetical elementary particle which mediates a scalar field in early universe cosmology. It can generate fluctuations during inflation, but does not itself drive inflation, instead it generates curvature perturbations at late times after the inflaton field has decayed and the decay products have redshifted away, when the curvaton is the dominant component of the energy density. It is used to generate a flat spectrum of CMB perturbations in models of inflation where the potential is otherwise too steep or in alternatives to inflation like the pre-Big Bang scenario.

Elementary particle Quantum particle having no known substructure

In particle physics, an elementary particle or fundamental particle is a subatomic particle with no sub structure, thus not composed of other particles. Particles currently thought to be elementary include the fundamental fermions, which generally are "matter particles" and "antimatter particles", as well as the fundamental bosons, which generally are "force particles" that mediate interactions among fermions. A particle containing two or more elementary particles is a composite particle.

Scalar field Assignment of numbers to points in space

In mathematics and physics, a scalar field associates a scalar value to every point in a space – possibly physical space. The scalar may either be a (dimensionless) mathematical number or a physical quantity. In a physical context, scalar fields are required to be independent of the choice of reference frame, meaning that any two observers using the same units will agree on the value of the scalar field at the same absolute point in space regardless of their respective points of origin. Examples used in physics include the temperature distribution throughout space, the pressure distribution in a fluid, and spin-zero quantum fields, such as the Higgs field. These fields are the subject of scalar field theory.

Cosmology Universe events since the Big Bang 13.8 billion years ago

Cosmology is a branch of astronomy concerned with the studies of the origin and evolution of the universe, from the Big Bang to today and on into the future. It is the scientific study of the origin, evolution, and eventual fate of the universe. Physical cosmology is the scientific study of the universe's origin, its large-scale structures and dynamics, and its ultimate fate, as well as the laws of science that govern these areas.

The model was proposed almost simultaneously in 2001 by three independent groups: Kari Enqvist and Martin S. Sloth, [1] David Wands and David H. Lyth, [2] Takeo Moroi and Tomo Takahashi. [3]

Kari Enqvist Finnish professor and writer

Kari-Pekka Enqvist is a professor of cosmology in the Department of Physical Sciences at the University of Helsinki. Enqvist was awarded his PhD in theoretical physics in 1983.

David Wands is Professor of Cosmology at the Institute of Cosmology and Gravitation, in the University of Portsmouth.

Professor David Lyth is a researcher in particle cosmology at the University of Lancaster. He has published over 165 papers as well as two books on early universe cosmology and cosmological inflation.

See also

Hubbles law observation in physical cosmology

Hubble's law, also known as the Hubble–Lemaître law, is the observation in physical cosmology that:

  1. Objects observed in deep space—extragalactic space, 10 megaparsecs (Mpc) or more—are found to have a redshift, interpreted as a relative velocity away from Earth;
  2. This Doppler shift-measured velocity of various galaxies receding from the Earth is approximately proportional to their distance from the Earth for galaxies up to a few hundred megaparsecs away.
Big Bang The prevailing cosmological model for the observable universe

The Big Bang theory is the prevailing cosmological model for the observable universe from the earliest known periods through its subsequent large-scale evolution. The model describes how the universe expanded from a very high-density and high-temperature state, and offers a comprehensive explanation for a broad range of phenomena, including the abundance of light elements, the cosmic microwave background (CMB), large scale structure and Hubble's law. If the observed conditions are extrapolated backwards in time using the known laws of physics, the prediction is that just before a period of very high density there was a singularity which is typically associated with the Big Bang. Physicists are undecided whether this means the universe began from a singularity, or that current knowledge is insufficient to describe the universe at that time. Detailed measurements of the expansion rate of the universe place the Big Bang at around 13.8 billion years ago, which is thus considered the age of the universe. After its initial expansion, the universe cooled sufficiently to allow the formation of subatomic particles, and later simple atoms. Giant clouds of these primordial elements later coalesced through gravity, eventually forming early stars and galaxies, the descendants of which are visible today. Astronomers also observe the gravitational effects of dark matter surrounding galaxies. Though most of the mass in the universe seems to be in the form of dark matter, Big Bang theory and various observations seem to indicate that it is not made out of conventional baryonic matter but it is unclear exactly what it is made out of.

Cosmological constant constant representing stress-energy density of the vacuum in Einsteins equation

In cosmology, the cosmological constant is the energy density of space, or vacuum energy, that arises in Albert Einstein's field equations of general relativity. It is closely associated to the concepts of dark energy and quintessence.

Notes

  1. Enqvist & Sloth (2002). "Adiabatic CMB perturbations in pre-Big Bang string cosmology". Nuclear Physics B. 626 (1–2): 395–409. arXiv: hep-ph/0109214 . Bibcode:2002NuPhB.626..395E. doi:10.1016/S0550-3213(02)00043-3.
  2. Lyth & Wands (2002). "Generating the curvature perturbation without an inflaton". Physics Letters B. 524 (1–2): 5–14. arXiv: hep-ph/0110002 . Bibcode:2002PhLB..524....5L. doi:10.1016/S0370-2693(01)01366-1.
  3. Moroi & Takahashi (2001). "Effects of Cosmological Moduli Fields on Cosmic Microwave Background". Physics Letters B. 522 (3–4): 215–221. arXiv: hep-ph/0110096 . Bibcode:2001PhLB..522..215M. doi:10.1016/S0370-2693(01)01295-3.


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In physical cosmology, cosmic inflation, cosmological inflation, or just inflation, is a theory of exponential expansion of space in the early universe. The inflationary epoch lasted from 10−36 seconds after the conjectured Big Bang singularity to some time between 10−33 and 10−32 seconds after the singularity. Following the inflationary period, the universe continues to expand, but at a less rapid rate.

Cosmic microwave background Universe events since the Big Bang 13.8 billion years ago

The cosmic microwave background, in Big Bang cosmology, is electromagnetic radiation as a remnant from an early stage of the universe, also known as "relic radiation". The CMB is faint cosmic background radiation filling all space. It is an important source of data on the early universe because it is the oldest electromagnetic radiation in the universe, dating to the epoch of recombination. With a traditional optical telescope, the space between stars and galaxies is completely dark. However, a sufficiently sensitive radio telescope shows a faint background noise, or glow, almost isotropic, that is not associated with any star, galaxy, or other object. This glow is strongest in the microwave region of the radio spectrum. The accidental discovery of the CMB in 1964 by American radio astronomers Arno Penzias and Robert Wilson was the culmination of work initiated in the 1940s, and earned the discoverers the 1978 Nobel Prize in Physics.

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