Abstract
view Abstract Citations (21) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A search for neutral hydrogen clouds in radio galaxies and in intergalactic space. Roberts, M. S. ; Steigerwald, D. G. Abstract A survey of 41 radio galaxies for H I absorption was made. One new absorption system was found, that in 3C 178. Upper limits to the H I optical depth are derived for the remaining systems. The observations extend to z = 0.34, corresponding to the low-frequency limit of the receiver. The absorption data indicate that, for an optical depth of 0.03 or less, the product of the spatial density of H I clouds and their projected area is less than 0.0022 per Mpc. Although this product is not particularly restrictive, it does indicate a discrete cloud H I mass-density model at least an order of magnitude less than the critical cosmological density. Some emission data supply an upper bound on the spatial density of H I clouds of mass above approximately one billion solar masses. Publication: The Astrophysical Journal Pub Date: November 1977 DOI: 10.1086/155634 Bibcode: 1977ApJ...217..883R Keywords: Absorption Spectra; Hydrogen Clouds; Intergalactic Media; Radio Astronomy; Radio Galaxies; Astronomical Models; Interstellar Extinction; Astrophysics full text sources ADS | data products NED (4) SIMBAD (1)
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