Bahcall and Salpeter1,2 and ourselves3 independently pointed out that the spectra of quasi-stellar sources of large red-shift would probably show absorption lines as a result of the gas contained in clusters of galaxies lying along the line of sight. If the temperature of the gas is a few times 105 degrees, which seems likely from other considerations, we might expect to observe absorption lines due to H I, C IV, and N V. A possible example of this absorption occurs4 in the spectrum of 1116 12, but the difference in red-shift between the source (z = 2.118 (ref. 5)) and the absorbing cloud (z = 1.949) is sufficiently small for the cloud to be possibly associated with the source itself.
- 1 - general ; 2 - general science & technology ; 3 - general science & technology
- 1 - sciences appliquees, technologies et medecines ; 2 - sciences biologiques et medicales ; 3 - sciences biologiques fondamentales et appliquees. psychologie ; 4 - invertebres