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Redshift quantization, also referred to as redshift periodicity, [1] redshift discretization, [2] preferred redshifts [3] and redshift-magnitude bands, [4] [5] is the hypothesis that the redshifts of cosmologically distant objects (in particular galaxies and quasars) tend to cluster around multiples of some particular value.
The angular size redshift relation for a Lambda cosmology, with on the vertical scale megaparsecs. The angular size redshift relation describes the relation between the angular size observed on the sky of an object of given physical size, and the object's redshift from Earth (which is related to its distance, d {\displaystyle d} , from Earth).
Mattig's formula was an important formula in observational cosmology and extragalactic astronomy which gives relation between radial coordinate and redshift of a given source. It depends on the cosmological model being used and is used to calculate luminosity distance in terms of redshift.
In physics, a redshift is an increase in the wavelength, and corresponding decrease in the frequency and photon energy, of electromagnetic radiation (such as light).The opposite change, a decrease in wavelength and increase in frequency and energy, is known as a blueshift, or negative redshift.
Gravitational redshift can be interpreted as a consequence of the equivalence principle (that gravitational effects are locally equivalent to inertial effects and the redshift is caused by the Doppler effect) [5] or as a consequence of the mass–energy equivalence and conservation of energy ('falling' photons gain energy), [6] [7] though there ...
A photometric redshift is an estimate for the recession velocity of an astronomical object such as a galaxy or quasar, made without measuring its spectrum.The technique uses photometry (that is, the brightness of the object viewed through various standard filters, each of which lets through a relatively broad passband of colours, such as red light, green light, or blue light) to determine the ...
The redshift z is often described as a redshift velocity, which is the recessional velocity that would produce the same redshift if it were caused by a linear Doppler effect (which, however, is not the case, as the velocities involved are too large to use a non-relativistic formula for Doppler shift). This redshift velocity can easily exceed ...
Modified Newtonian dynamics (MOND) is a theory that proposes a modification of Newton's second law to account for observed properties of galaxies.Its primary motivation is to explain galaxy rotation curves without invoking dark matter, and is one of the most well-known theories of this class.