Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Tracing Ram-Pressure Stripping with Warm Molecular Hydrogen Emission   We use the Spitzer Infrared Spectrograph (IRS) to study four infalling
cluster galaxies with signatures of on-going ram-pressure stripping. H$_2$
emission is detected in all four; two show extraplanar H$_2$ emission. The
emission usually has a warm (T $\sim$ $115 - 160$K) and a hot (T $\sim$ 400 $-$
600K) component that is approximately two orders of magnitude less massive than
the warm one. The warm component column densities are typically $10^{19} -
10^{20}$ cm$^{-2}$ with masses of $10^6 - 10^8 M_\odot$. The warm H$_2$ is
anomalously bright compared with normal star-forming galaxies and therefore may
be excited by ram-pressure. In the case of CGCG 97-073, the H$_2$ is offset
from the majority of star formation along the direction of the galaxy's motion
in the cluster, suggesting it is forming in the ram-pressure wake of the
galaxy. Another galaxy, NGC 4522, exhibits a warm H$_2$ tail approximately 4
kpc in length. These results support the hypothesis that H$_2$ within these
galaxies is shock-heated from the interaction with the intracluster medium.
Stripping of dust is also a common feature of the galaxies. For NGC 4522, where
the distribution of dust at 8 $\mu$m is well resolved, knots and ripples
demonstrate the turbulent nature of the stripping process. The H$\alpha$ and 24
$\mu$m luminosities show that most of the galaxies have star formation rates
comparable to similar mass counterparts in the field. Finally, we suggest a
possible evolutionary sequence primarily related to the strength of
ram-pressure a galaxy experiences to explain the varied results observed in our
sample.

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The categories of this paper are: cs
18
The categories of this paper are: econ
35
The categories of this paper are: mtrl-th
33
The categories of this paper are: plasm-ph
26
The categories of this paper are: bayes-an
5
The categories of this paper are: gr-qc
14
The categories of this paper are: math-ph
4
The categories of this paper are: cond-mat
0
The categories of this paper are: hep-ph
19
The categories of this paper are: eess
9
The categories of this paper are: nlin
23
The categories of this paper are: solv-int
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex
37
The categories of this paper are: supr-con
34
The categories of this paper are: chem-ph