| Cosmology |
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| Objects and processes under study |
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| Universe History |
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| Observed processes |
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| Theoretical studies |
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ΛCDM (read “Lambda-SidiEm”) - short for Lambda-Cold Dark Matter , a modern standard cosmological model [1] , in which the spatially flat Universe is filled with dark energy (described by the cosmological constant Λ in Einstein’s equations ) and cold dark matter ( eng. Cold Dark Matter ). According to this model, the age of the Universe is 13.75 ± 0.11 billion years.
The model assumes that the general theory of relativity is the correct theory of gravity on cosmological scales. It originated in the late 1990s and suggests inflation to explain the spatial flatness of the Universe and the initial spectrum of perturbations.
Content
Introduction
Most modern cosmological models are based on the cosmological principle , which states that our location in the Universe is not particularly distinguished and that on a sufficiently large scale, the Universe looks the same in all directions (isotropy) and from every place (uniformity) [2] . This principle is not an unconditional requirement - a postulate , but rather a presumption - that is, it is considered true until proven otherwise.
The model includes the expansion of the Universe , which is well confirmed by the cosmological redshift of the spectra of distant galaxies and quasars .
History
The discovery of the cosmic microwave background in 1965 confirmed the key prediction of the cosmology of the Big Bang . From this point on, it was assumed that the Universe expands over time, and its early state was dense and hot.
The rate of expansion depends on the content and type of matter and energy in the Universe and, in particular, on whether the total density is higher or lower than the so-called critical density . In the 1970s, cosmologists focused their attention on a purely baryon model, but this approach had serious problems explaining the formation of galaxies, given the very small anisotropy of the CMB , which was already received serious estimates from above. In the early 1980s, it became clear that this problem could be solved if it was assumed that cold dark matter dominates baryon .
Different models offer different ratios of ordinary and dark energies and masses. In the 1980s, most studies focused on a model of cold dark matter with a critical density at a ratio of about 95% dark matter and 5% baryons: these papers successfully explained the formation of galaxies and clusters of galaxies, but in the 1990s it turned out that the results of large-scale the distribution of galaxies in combination with the measured anisotropy of the background radiation contradicts such a model. [3]
The ΛCDM model became the standard soon after the discovery of the acceleration of the expansion of the Universe in 1998, since the contradictions mentioned above were simply and naturally resolved in it.
Notes
- ↑ Standard cosmological model
- ↑ Andrew Liddle. An Introduction to Modern Cosmology (2nd ed.). London: Wiley, 2003.
- ↑ Longair MS 14.7. Variations on the Theme of Cold Dark Matter // Galaxy Formation. - Berlin: Springer, 2008. - p. 415-419. - 760 p. - ISBN 978-3-540-73477-2 .