Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Collisional heating as the origin of filament emission in galaxy
  clusters   [Abridged] Photoionization, whether by starlight or other sources, has
difficulty in accounting for the observed spectra of the optical filaments that
often surround central galaxies in large clusters. Our first paper examined
whether heating by energetic particles or dissipative MHD wave can account for
the observations. Here we include atomic and low-ionization regions. The model
of the hydrogen atom, along with all elements of the H-like iso-electronic
sequence, is now fully nl-resolved. We show how the predicted HI spectrum
differs from the pure recombination case. The second update is to the rates for
H^0 - H2 inelastic collisions. We now use the values computed by Wrathmall et
al. The rates are often much larger.
  We calculate the chemistry, ionization, temperature, gas pressure, and
emission-line spectrum for a wide range of gas densities and collisional
heating rates. We assume that the filaments are magnetically confined and free
to move along field lines so that the gas pressure is equal to that of the
surrounding hot gas. A mix of clouds, some being dense and cold and others hot
and tenuous, can exist. The observed spectrum will be the integrated emission
from clouds with different densities and temperatures but the same pressure. We
assume that the gas filling factor is given by a power law in density. The
power-law index is set by matching the observed intensities of IR H2 lines
relative to optical HI lines. We conclude that the filaments are heated by
ionizing particles, either conducted in from surrounding regions or produced in
situ by processes related to MHD waves.

21
The categories of this paper are: adap-org
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
23
The categories of this paper are: solv-int
18
The categories of this paper are: econ
30
The categories of this paper are: q-alg
32
The categories of this paper are: atom-ph
8
The categories of this paper are: hep-ex
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
34
The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
16
The categories of this paper are: stat
5
The categories of this paper are: gr-qc