![]() The theoretical framework of our model is built upon the assumption that the observed redshift zobs is fully determined by the true metric of the Universe. In other words, wavelengths are shifted by less than one part in 30,000. The remapping is a monotonic function z f ( zobs) and the standard redshift mapping is its special case when f is an identity function. In this case, the gravitational redshift suffered by a photon emitted from the star’s surface is a tiny 3 × 10 -4. Where z is the gravitational redshift, G is Newton’s gravitational constant, M is the mass of the object, r is the photon’s starting distance from M, and c is the speed of light. Although it sounds extreme, this is still considered a relatively weak field, and the gravitational redshift can be approximated by: wavelength shift measured 0 represents the real wavelength. The observed wavelength of a photon falling into a gravitational well will be shortened, or gravitationally ‘blueshifted’, as it gains energy.Īs an example, take the white dwarf star Sirius B, with a gravitational field ~100,000 times as strong as the Earth’s. The formula for Redshift is z 0 0 z stands for redshift. This effect was confirmed in laboratory experiments conducted in the 1960s. This corresponds to an increase in the wavelength of the photon, or a shift to the red end of the electromagnetic spectrum – hence the name: gravitational redshift. If the energy of the photon decreases, the frequency also decreases. The redshift z is related to the scale factor a by 0 1+z a0 a: From now on, the quantity with the subscript 0 means the value at present. The well-measured quantity of a far distant object is the redshift of light it emitted due to the expansion of the universe. ![]() ![]() Photons must expend energy to escape, but at the same time must always travel at the speed of light, so this energy must be lost through a change of frequency rather than a change in speed. to look into the redshift - luminosity distance relation 1, 2. Einstein’s theory of general relativity predicts that the wavelength of electromagnetic radiation will lengthen as it climbs out of a gravitational well. ![]()
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