Investigations of redshifted clouds with the 21 cm line.
Abstract
The paper describes investigations of redshifted clouds with the 21 cm line. 16 redshift systems exhibiting Mg II and Fe I absorption detected a 21 cm absorption at za = 0.394985 in PKS 1229-02. The null observations are interpreted in terms of turbulent gas that is optically thick in the resonance transitions, but thin to 21 cm radiation. The L (alpha) absorption, however, is sensitive to the presence of very opaque clouds, and a 21 cm absorption line was found at zA = 1.77642; the comparison between the L (alpha) and 21 cm absorption spectra restricts the hydrogen spin temperature to below 1000 K. 21 cm emission was found in only 9% of 28 spiral galaxies; the coincidence of 21 cm and optical absorption redshifts implies space-time invariance of certain physical constants throughout most of the observable universe.
- Publication:
-
Physica Scripta
- Pub Date:
- 1980
- DOI:
- 10.1088/0031-8949/21/5/029
- Bibcode:
- 1980PhyS...21..744W
- Keywords:
-
- Centimeter Waves;
- Clouds;
- Interstellar Matter;
- Line Spectra;
- Quasars;
- Red Shift;
- Absorption Spectra;
- Emission Spectra;
- Hydrogen Clouds;
- Iron;
- Magnesium;
- Optical Thickness;
- Radio Emission;
- Space-Time Functions;
- Spin Temperature;
- Astrophysics;
- Galaxies:Intergalactic Matter;
- Intergalactic Matter:Quasi-Stellar Objects