Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: CIV Absorption From Galaxies in the Process of Formation   We investigate the heavy element QSO absorption systems caused by gas
condensations at high redshift which evolve into galaxies with circular
velocity of 100 to 200 km/s at the present epoch. Artificial QSO spectra were
generated for a variety of lines-of-sight through regions of the universe
simulated with a hydrodynamics code. The CIV and HI absorption features in
these spectra closely resemble observed CIV and HI absorption systems over a
wide range in column density. CIV absorption complexes with multiple-component
structure and velocity spreads up to about 600 km/s are found. The broadest
systems are caused by lines-of-sight passing through groups of protogalactic
clumps with individual velocity dispersions of less than 150 km/s aligned along
filamentary structures. The temperature of most of the gas does not take the
photoionization equilibrium value. This invalidates density and size estimates
derived from thermal equilibrium models. Consequences for metal abundance
determinations are briefly discussed. We predict occasional exceptionally large
ratios of CIV to HI column density (up to a third) for lines-of-sight passing
through compact halos of hot gas with temperature close to 3 10^5 K. Our model
may be able to explain both high-ionization multi-component heavy-element
absorbers and damped Lyman alpha systems as groups of small protogalactic
clumps.

13
The categories of this paper are: quant-ph
4
The categories of this paper are: cond-mat
3
The categories of this paper are: physics
15
The categories of this paper are: nucl-ex
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
5
The categories of this paper are: gr-qc
8
The categories of this paper are: hep-ex
26
The categories of this paper are: bayes-an
33
The categories of this paper are: plasm-ph
32
The categories of this paper are: atom-ph
34
The categories of this paper are: chem-ph
7
The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol