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Session 51 - Galaxy Evolution and the Intergalactic Medium.
Display session, Wednesday, June 10
An analysis of a recent Lyman alpha cloud data sample containing more than 400 lines with redshift between 3.4 and 4.1 is presented. The distributions of the neutral hydrogen column density and of the Doppler width parameter are studied. The dependence of these two parameters on redshift and their correlation with one another is also investigated. Our analysis indicates that the cumulative distribution is a more effective tool than the differential distribution in analyzing the column density and the Doppler parameter since no binning is involved. The distrbution of the column density is more complicated than what is commonly believed, since it cannot be fitted with a power law or a double power law. There is a paucity of Lyman alpha lines with Doppler parameters less than 15 km/s indicating a possible lower limit on cloud temperatures of about 13,500 K. Although the column density and the Doppler parameter display a similar dependence on redshift, their correlation with one another is shown to be statistically weak.
Program listing for Wednesday