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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 ...
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 [27] (where ℓ P is the Planck length).
Distance measures are used in physical cosmology to give a natural notion of the distance between two objects or events in the universe.They are often used to tie some observable quantity (such as the luminosity of a distant quasar, the redshift of a distant galaxy, or the angular size of the acoustic peaks in the cosmic microwave background (CMB) power spectrum) to another quantity that is ...
The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is an interferometric radio telescope at the Dominion Radio Astrophysical Observatory in British Columbia, Canada which consists of four antennas consisting of 100 x 20 metre cylindrical parabolic reflectors (roughly the size and shape of snowboarding half-pipes) with 1024 dual-polarization radio receivers suspended on a support above ...
In astrophysics, the term "cosmography" is beginning to be used to describe attempts to determine the large-scale matter distribution and kinematics of the observable universe, dependent on the Friedmann–Lemaître–Robertson–Walker metric but independent of the temporal dependence of the scale factor on the matter/energy composition of the Universe.