Scalar field dark matter
Encyclopedia
Astrophysics
Astrophysics is the branch of astronomy that deals with the physics of the universe, including the physical properties of celestial objects, as well as their interactions and behavior...
and cosmology
Physical cosmology
Physical cosmology, as a branch of astronomy, is the study of the largest-scale structures and dynamics of the universe and is concerned with fundamental questions about its formation and evolution. For most of human history, it was a branch of metaphysics and religion...
scalar field dark matter is a classical, minimally coupled, real scalar field postulated to account for the inferred dark matter
Dark matter
In astronomy and cosmology, dark matter is matter that neither emits nor scatters light or other electromagnetic radiation, and so cannot be directly detected via optical or radio astronomy...
.
Background
The universe may be accelerating, fueled perhaps by a cosmological constant or someother field possessing long range ‘repulsive’ effects. A model must predict the correct form for
the large scale clustering spectrum, account for cosmic microwave background
Cosmic microwave background radiation
In cosmology, cosmic microwave background radiation is thermal radiation filling the observable universe almost uniformly....
anisotropies on large and intermediate angular scales, and provide agreement with the luminosity distance relation
Distance measures (cosmology)
Distance measures are used in physical cosmology to give a natural notion of the distance between two objects or events in the universe. They are often used to tie some observable quantity to another quantity that is not directly...
obtained from observations of high redshift
Redshift
In physics , redshift happens when light seen coming from an object is proportionally increased in wavelength, or shifted to the red end of the spectrum...
supernova
Supernova
A supernova is a stellar explosion that is more energetic than a nova. It is pronounced with the plural supernovae or supernovas. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months...
e. The modeled evolution of the universe includes a large amount of unknown matter in order to agree with such observations. This matter has two components cold dark matter
Cold dark matter
Cold dark matter is the improvement of the big bang theory that contains the additional assumption that most of the matter in the Universe consists of material that cannot be observed by its electromagnetic radiation and whose constituent particles move slowly...
and dark energy
Dark energy
In physical cosmology, astronomy and celestial mechanics, dark energy is a hypothetical form of energy that permeates all of space and tends to accelerate the expansion of the universe. Dark energy is the most accepted theory to explain recent observations that the universe appears to be expanding...
. Each contributes to the theory of the origination of galaxies and the expansion of the universe. The universe must have a critical density, a density not explained by baryonic matter (ordinary matter
Matter
Matter is a general term for the substance of which all physical objects consist. Typically, matter includes atoms and other particles which have mass. A common way of defining matter is as anything that has mass and occupies volume...
) alone.
Scalar field
The dark matter can be modeled as a scalar field using two fitted parameters. In this picture the dark matter consists of an ultralight particle with a mass of 1.1 × 10−23 eVThe uncertainty in position of a particle is larger than its Compton wavelength
Compton wavelength
The Compton wavelength is a quantum mechanical property of a particle. It was introduced by Arthur Compton in his explanation of the scattering of photons by electrons...
, and for some reasonable estimates of particle mass and density of dark matter there is no point talking about the individual particle’s position and momentum. The dark matter is more like a wave than a particle, and the galactic halo
Galactic halo
The term galactic halo is used to denote an extended, roughly spherical component of a galaxy, which extends beyond the main, visible component. It can refer to any of several distinct components which share these properties:* the galactic spheroid...
s are giant systems of condensed bose liquid. The dark matter can be described as a Bose-Einstein condensate of the ultralight quanta of the field
and as boson stars. The enormous Compton wavelength of these particles prevents structure formation on small subgalactic scales, which is a major problem in traditional cold dark matter models.
The collapse of initial overdensities is studied in Refs.
See also
- Weakly interacting massive particles
- Minimal Supersymmetric Standard ModelMinimal Supersymmetric Standard ModelThe Minimal Supersymmetric Standard Model is the minimal extension to the Standard Model that realizes supersymmetry, although non-minimal extensions do exist. Supersymmetry pairs bosons with fermions; therefore every Standard Model particle has a partner that has yet to be discovered...
- NeutralinoNeutralinoIn particle physics, the neutralino is a hypothetical particle predicted by supersymmetry. There are four neutralinos that are fermions and are electrically neutral, the lightest of which is typically stable...
- AxionAxionThe axion is a hypothetical elementary particle postulated by the Peccei-Quinn theory in 1977 to resolve the strong CP problem in quantum chromodynamics...
- Dark matter haloDark matter haloA dark matter halo is a hypothetical component of a galaxy, which extends beyond the edge of the visible galaxy and dominates the total mass. Since they consist of dark matter, halos cannot be observed directly, but their existence is inferred through their effects on the motions of stars and gas...
- Light dark matterLight dark matterIn astronomy and cosmology, light dark matter refers to dark matter Weakly interacting massive particle candidates with masses less than 1 GeV. These particles are heavier than warm dark matter and hot dark matter, but are lighter than the traditional forms of cold dark matter...
- Hot dark matterHot dark matterHot dark matter is a hypothetical form of dark matter which consists of particles that travel with ultrarelativistic velocities. The best candidate for the identity of hot dark matter is the neutrino. Neutrinos have very small masses, and do not take part in two of the four fundamental forces, the...
- Warm dark matterWarm dark matterWarm dark matter is a hypothesized form of dark matter that has properties intermediate between those of hot dark matter and cold dark matter, causing structure formation to occur bottom-up from above their free-streaming scale, and top-down below their free streaming scale. The most common WDM...