view Abstract Citations (4) References (27) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A search for 21 centimeter absorption in quasars of high redshift. Perrenod, S. C. ; Chaisson, E. J. Abstract Observational limits on redshifted 21-cm absorption along the line of sight to several of the most highly redshifted quasars have been obtained. Upper limits on the neutral-hydrogen column density as low as 1.6 x 10 to the 19th per sq cm are found at frequencies (350 MHz-450 MHz) corresponding to known optical absorption redshift systems. The upper limits on the amount of hydrogen do not rule out the intervening hypothesis for the origin of the optical absorption systems. Publication: The Astrophysical Journal Pub Date: August 1979 DOI: 10.1086/157263 Bibcode: 1979ApJ...232...49P Keywords: Absorption Spectra; Astronomical Spectroscopy; Quasars; Red Shift; Centimeter Waves; Gas Density; Hydrogen; Microwave Spectra; Astrophysics; Neutral Hydrogen:Quasars; Quasars:Redshifts full text sources ADS |