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In astronomy, dark matter is an invisible and hypothetical form of matter that does not interact with light or other electromagnetic radiation.Dark matter is implied by gravitational effects which cannot be explained by general relativity unless more matter is present than can be observed.
The density of dark matter in an expanding universe decreases more quickly than dark energy, and eventually the dark energy dominates. Specifically, when the volume of the universe doubles, the density of dark matter is halved, but the density of dark energy is nearly unchanged (it is exactly constant in the case of a cosmological constant).
A MAssive Compact Halo Object (MACHO) is a kind of astronomical body that might explain the apparent presence of dark matter in galactic halos.A MACHO is a body that emits little or no radiation and drifts through interstellar space unassociated with any planetary system (and may or may not be composed of normal baryonic matter).
Sub-GeV dark matter has been used to explain the positron excess in the Galactic Center observed by INTEGRAL, excess gamma rays from the Galactic Center [7] and extragalactic sources. It has also been suggested that light dark matter may explain a small discrepancy in the measured value of the fine structure constant in different experiments. [8]
The universe may be accelerating, fueled perhaps by a cosmological constant or some other field possessing long range 'repulsive' effects. A model must predict the correct form for the large scale clustering spectrum, [3] account for cosmic microwave background anisotropies on large and intermediate angular scales, and provide agreement with the luminosity distance relation obtained from ...
Dark radiation (also dark electromagnetism) [1] is a postulated type of radiation that mediates interactions of dark matter.. By analogy to the way photons mediate electromagnetic interactions between particles in the Standard Model (called baryonic matter in cosmology), dark radiation is proposed to mediate interactions between dark matter particles. [1]
The founding principle of direct dark matter detection is that since dark matter is known to exist in the local universe, as the Earth, Solar System, and the Milky Way Galaxy carve out a path through the universe they must intercept dark matter, regardless of what form it takes. Direct detection of dark matter faces several practical challenges.
The Navarro–Frenk–White (NFW) profile is a spatial mass distribution of dark matter fitted to dark matter halos identified in N-body simulations by Julio Navarro, Carlos Frenk and Simon White. [ 1 ] [ 2 ] The NFW profile is one of the most commonly used model profiles for dark matter halos. [ 3 ]