Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Probing for Dark Matter within Spiral Galaxy Disks   We explore the relative importance of the stellar mass density as compared to
the inner dark halo, using the observed gas kinematics throughout the disk of
the spiral galaxy NGC 4254 (Messier 99). We perform hydrodynamical simulations
of the gas flow for a sequence of gravitational potentials in which we vary the
stellar disk contribution to the total potential. This stellar portion of the
potential was derived empirically from color corrected K-band photometry
reflecting the spiral arms in the stellar mass, while the halo was modelled as
an isothermal sphere. The simulated gas density and the gas velocity field are
then compared to the observed stellar spiral arm morphology and to the H-alpha
gas kinematics. We find that this method is a powerful tool to determine the
corotation radius of the spiral pattern and that it can be used to place an
upper limit on the mass of the stellar disk. For the case of the galaxy NGC
4254 we find R_cr = 7.5 +/- 1.1 kpc, or R_cr = 2.1 R_exp(K'). We also
demonstrate that for a maximal disk the prominent spiral arms of the stellar
component over-predict the non-circular gas motions unless an axisymmetric dark
halo component contributes significantly (>~ 1/3) to the total potential inside
2.2 K-band exponential disk scale lengths.

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The categories of this paper are: chem-ph
14
The categories of this paper are: math-ph
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The categories of this paper are: q-alg
13
The categories of this paper are: quant-ph
0
The categories of this paper are: hep-ph
11
The categories of this paper are: hep-lat
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The categories of this paper are: dg-ga
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The categories of this paper are: ao-sci
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The categories of this paper are: funct-an
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The categories of this paper are: nucl-ex
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The categories of this paper are: cond-mat
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The categories of this paper are: acc-phys
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The categories of this paper are: comp-gas
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The categories of this paper are: econ
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The categories of this paper are: mtrl-th
7
The categories of this paper are: hep-th