Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evolution of the Cosmic Gas and the Relic Supernova Neutrino Background   Using the redshift evolution of the cosmic gas, as inferred from QSO
absorption line studies, we calculate the past supernova rate and the relic
supernova neutrino background. Using this new technique we find the predicted
relic neutrino flux at low energies to be at least an order of magnitude below
previous estimates. We argue that the evolution of the cosmic gas is consistent
with a large decrease in the number of early-type galaxies at redshifts $\sim
3$, and that this evolution is the source of the reduction in the predicted
neutrino flux. Additional observational constraints from recent redshift
surveys lead us to propose a modified model for the evolution of the cosmic gas
in which significant infall at low redshift occurs. We discuss the possible
relevance of our calculations to the X-ray emitting metal-enriched gas observed
in the intergalactic medium.

1
The categories of this paper are: cs
12
The categories of this paper are: nucl-th
24
The categories of this paper are: dg-ga
25
The categories of this paper are: patt-sol
5
The categories of this paper are: gr-qc
3
The categories of this paper are: physics
28
The categories of this paper are: alg-geom
11
The categories of this paper are: hep-lat
37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
22
The categories of this paper are: chao-dyn
27
The categories of this paper are: comp-gas
26
The categories of this paper are: bayes-an
21
The categories of this paper are: adap-org
36
The categories of this paper are: cmp-lg
9
The categories of this paper are: nlin