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An atom of neutral hydrogen consists of an electron bound to a proton.The lowest stationary energy state of the bound electron is called its ground state.Both the electron and the proton have intrinsic magnetic dipole moments ascribed to their spin, whose interaction results in a slight increase in energy when the spins are parallel, and a decrease when antiparallel.
In cosmology, intensity mapping is an observational technique for surveying the large-scale structure of the universe by using the integrated radio emission from unresolved gas clouds. In its most common variant, 21 cm intensity mapping, the 21cm emission line of neutral hydrogen is used to trace the gas. The hydrogen follows fluctuations in ...
The signal is possibly due to ultraviolet light from the first stars in the Universe altering the emission of the 21cm line by lowering the temperature of the hydrogen relative to the cosmic microwave background (the mechanism is Wouthuysen–Field coupling).
Tianlai Arrays. The Tianlai experiment (Chinese: 天籁) is a radio astronomy experiment run by the National Astronomical Observatories, Chinese Academy of Sciences (NAOC). [1] [2] Its aim is to develop the key techniques of intensity mapping observation for the redshifted 21cm line of neutral hydrogen, in order to probe the large-scale structure, and to detect and measure the dark energy ...
The Primeval Structure Telescope (PaST), also called 21 Centimetre Array (21CMA), [1] is a Chinese radio telescope array designed to detect the earliest luminous objects in the universe, including the first stars, supernova explosions, and black holes, in the range of 100 to 1 billion years ago. [2]
In standard cosmology, comoving distance and proper distance (or physical distance) are two closely related distance measures used by cosmologists to define distances between objects. Comoving distance factors out the expansion of the universe , giving a distance that does not change in time except due to local factors, such as the motion of a ...
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Thus, the Lambda-CDM model, the current standard model of cosmology which uses the FLRW metric, includes the cosmological constant, which is measured to be on the order of 10 −52 m −2. It may be expressed as 10 −35 s −2 (multiplying by c 2 ≈ 10 17 m 2 ⋅s −2) or as 10 −122 ℓ P −2 [29] (where ℓ P is the Planck length).