Search results
Results from the WOW.Com Content Network
The hydrogen line, 21 centimeter line, or H I line [a] is a spectral line that is created by a change in the energy state of solitary, electrically neutral hydrogen atoms. It is produced by a spin -flip transition, which means the direction of the electron's spin is reversed relative to the spin of the proton.
The Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER) is a radio interferometer funded by the National Science Foundation [1] to detect 21 cm hydrogen (HI) fluctuations occurring when the first galaxies ionized intergalactic gas at around 500 million years after the Big Bang.
These are predominantly hosted in galaxies, so the neutral hydrogen signal is effectively a tracer of the galaxy distribution. As with galaxy redshift surveys, intensity mapping observations can be used to measure the geometry and expansion rate of the Universe (and therefore the properties of dark energy [ 1 ] ) by using the baryon acoustic ...
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 ...
Horn antenna used by Harold I. Ewen and Edward M. Purcell at the Lyman Laboratory of Physics at Harvard University in 1951 for the first detection of radio radiation from nuclear atomic hydrogen gas in the Milky Way at a wavelength of 21 cm. Now at National Radio Astronomy Observatory. [1]
The Hydrogen Intensity and Real-time Analysis eXperiment (HIRAX) is an interferometric array of 1024 6-meter (20ft) diameter radio telescopes, operating at 400-800MHz, that will be deployed at the Square Kilometer Array site in the Karoo region of South Africa.
Nonetheless, Ewen and Purcell agreed that his thesis topic should be to construct a microwave spectrometer to find a lower limit on the detectability of the 21-cm hydrogen line. [6] With a $500 grant from the AAA&S, Ewen was able to purchase components to construct a pyramidal horn antenna and a 21-cm receiver.
Wouthuysen–Field coupling is a mechanism that couples the spin temperature of neutral hydrogen to Lyman-alpha radiation, which decouples the neutral hydrogen from the CMB. The energy of the Lyman-alpha transition is 10.2 eV—this energy is approximately two million times greater than the hydrogen line, and is produced by astrophysical ...