Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The b Distribution of the Lya Forest: Probing Cosmology and the
  Intergalactic Medium   We investigate a method to determine the temperature-density relation of the
intergalactic medium (IGM) at z~2-4 using quasar absorption line systems. Using
a simple model combined with numerical simulations we show that there is a
lower cutoff in the distribution of column density (NHI) and line width (b
parameter). The location of this cutoff can be used to determine the
temperature-density relation (under certain conditions). We describe and test
an algorithm to do this. The method works as long as the amplitude of
fluctuations on these scales (~100 kpc) is sufficiently large. Models with less
power can mimic higher temperatures. A preliminary application is made to data
from two quasar lines-of-sight, and we determine an upper limit to the
temperature of the IGM. Finally, we examine the full distribution of
b-parameters and show that this is completely specified by just two parameters:
the temperature of the gas and the amplitude of the power spectrum. Using the
temperature upper limit measured with the NHI-b cutoff method, we derive an
upper limit to the amplitude of the power spectrum.

8
The categories of this paper are: hep-ex
4
The categories of this paper are: cond-mat
15
The categories of this paper are: nucl-ex
22
The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga
14
The categories of this paper are: math-ph
37
The categories of this paper are: supr-con
5
The categories of this paper are: gr-qc
36
The categories of this paper are: cmp-lg
3
The categories of this paper are: physics
7
The categories of this paper are: hep-th
20
The categories of this paper are: acc-phys
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
0
The categories of this paper are: hep-ph
13
The categories of this paper are: quant-ph