Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An Imaging Study of the Globular Cluster Systems of NGC 1407 and NGC
  1400   We present wide-field Keck telescope imaging of the globular cluster (GC)
systems around NGC 1407 and NGC 1400 in the Eridanus galaxy cloud. This is
complemented by Hubble Space Telescope images from the Advanced Camera for
Surveys of NGC 1407 and Wide Field and Planetary Camera 2 images of NGC 1400.
We clearly detect bimodality in the GC colour distribution of NGC 1407. The
blue GC subpopulation has a mean colour of B-I = 1.61 and a relative
contribution of around 40%, whereas the red subpopulation with B-I = 2.06
contributes 60% to the overall GC system. Assuming old ages, this corresponds
to [Fe/H] = -1.45 and -0.19. Both subpopulations are intrinsically broad in
colour (indicating a range in ages and/or metallicities), with the red
subpopulation being broader than the blue. The GC colour distribution for NGC
1400 is less clear cut than for NGC 1407, however, we also find evidence for a
bimodal distribution. We find the NGC 1407 red GCs to be 20% smaller in size
than the blue ones. We find both GC systems to possess a GC surface density
distribution which is largely constant in these inner galaxy regions. We fit
isothermal-like profiles and derive GC system core radii of 9.4 kpc for NGC
1407 and 5.8 kpc for NGC 1400. For NGC 1407 we are able to separate the surface
density distribution into blue and red subpopulations, giving 17.8 and 7.6 kpc
respectively. Outside this central region, the radial profile of the GC surface
density is similar to that of the galaxy light for NGC 1407 but it is flatter
for NGC 1400. A fit to the GC luminosity function gives a distance modulus of
31.6, which is in good agreement with distances based on the Faber-Jackson
relation and the Virgo infall corrected velocity.

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The categories of this paper are: math-ph
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The categories of this paper are: stat
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The categories of this paper are: eess
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The categories of this paper are: math
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The categories of this paper are: hep-ex
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The categories of this paper are: nlin
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The categories of this paper are: nucl-th
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The categories of this paper are: econ
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The categories of this paper are: alg-geom
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The categories of this paper are: mtrl-th
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The categories of this paper are: comp-gas
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The categories of this paper are: chao-dyn
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The categories of this paper are: plasm-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: q-alg
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The categories of this paper are: q-fin