Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Cool ISM in Elliptical Galaxies. II. Gas Content in the Volume -
  Limited Sample and Results from the Combined Elliptical and Lenticular
  Surveys   We report new observations of atomic and molecular gas in a volume limited
sample of elliptical galaxies. Combining the elliptical sample with an earlier
and similar lenticular one, we show that cool gas detection rates are very
similar among low luminosity E and SO galaxies but are much higher among
luminous S0s. Using the combined sample we revisit the correlation between cool
gas mass and blue luminosity which emerged from our lenticular survey, finding
strong support for previous claims that the molecular gas in ellipticals and
lenticulars has different origins. Unexpectedly, however, and contrary to
earlier claims, the same is not true for atomic gas. We speculate that both the
AGN feedback and merger paradigms might offer explanations for differences in
detection rates, and might also point towards an understanding of why the two
gas phases could follow different evolutionary paths in Es and S0s. Finally we
present a new and puzzling discovery concerning the global mix of atomic and
molecular gas in early type galaxies. Atomic gas comprises a greater fraction
of the cool ISM in more gas rich galaxies, a trend which can be plausibly
explained. The puzzle is that galaxies tend to cluster around
molecular-to-atomic gas mass ratios near either 0.05 or 0.5.

21
The categories of this paper are: adap-org
23
The categories of this paper are: solv-int
4
The categories of this paper are: cond-mat
36
The categories of this paper are: cmp-lg
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
10
The categories of this paper are: q-bio
7
The categories of this paper are: hep-th
26
The categories of this paper are: bayes-an
34
The categories of this paper are: chem-ph
8
The categories of this paper are: hep-ex
27
The categories of this paper are: comp-gas
24
The categories of this paper are: dg-ga
3
The categories of this paper are: physics