Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Small Scale Structure at High Redshift: III. The Clumpiness of the
  Intergalactic Medium on Sub-kpc Scales   Spectra from the Keck HIRES instrument of the Lyman alpha forests in the
lines of sight to the A and C components of the gravitationally lensed QSO
Q1422+231 were used to investigate the structure of the intergalactic medium at
mean redshift z = 3.3 on sub-kpc scales. We measured the cross-correlation
amplitude between the two Lyman alpha forests for a mean transverse separation
of 120 pc, and computed the RMS column density and velocity differences between
individual absorption systems seen in both lines of sight. The RMS differences
between the velocity centroids of the Lyman alpha forest lines were found to be
less than about 400 m/s, for unsaturated absorption lines with column densities
in the range 12<log N(HI)<14.13. The rate of energy transfer into the low
density IGM on a typical scale of 100 pc seems to be lower by 3-4 orders of
magnitude than the rate measured earlier for strong CIV metal absorption
systems. The tight correlation between HI column density and baryonic density
in the intergalactic medium was used to obtain an upper limit on the RMS
fluctuations of the baryonic density field. The fraction of the absorption
lines that are different across the lines of sight was used to determine the
filling factor of the universe for gas which has suffered recent hydrodynamic
disturbances. We thereby derived upper limits on the filling factor of galactic
outflows at high redshift. Short-lived, short-range ancient winds are
essentially unconstrained by this method but strong winds blowing for a
substantial fraction of a Hubble time (at z = 3.3) appear to fill less than 20
percent of the volume of the universe.

15
The categories of this paper are: nucl-ex
19
The categories of this paper are: eess
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
33
The categories of this paper are: plasm-ph
13
The categories of this paper are: quant-ph
32
The categories of this paper are: atom-ph
28
The categories of this paper are: alg-geom
11
The categories of this paper are: hep-lat
18
The categories of this paper are: econ
2
The categories of this paper are: math
36
The categories of this paper are: cmp-lg
0
The categories of this paper are: hep-ph
8
The categories of this paper are: hep-ex