The statistical distribution of the neutral-hydrogen content of elliptical galaxies.

An examination has been conducted of the form of the distribution function for the relative H I content, MH I/LB, of elliptical galaxies, using a data set derived from all recent H I observations of ellipticals in the literature. The characteristics of this combined data set are poorly defined, but upon examination it appears to be reassuringly free of built-in biases and correlations. The data set contains 152 galaxies; 23 of these have been detected in the H I line. The detected galaxies are shown to be more H I rich on average than the galaxies in the whole sample. A method for recovering the intrinsic distribution of MH I/LB, using both detection and upper-limit data, is described, and the data are shown to be consistent with a shallow power-law differential distribution N approximately (MH I/LB) to the -1.5th. This distribution is quite different from that for spirals, where N(MH I/LB) has a well-defined mean value and a small dispersion. This result strongly suggests that the gas and star contents of ellipticals are decoupled, i.e., the gas has an external origin.