Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Scaling relations in early-type galaxies belonging to groups   We present a photometric analysis of a large sample of early-type galaxies in
16 nearby groups, imaged with the Wide-Field Camera on the Isaac Newton
Telescope. Using a two-dimensional surface brightness decomposition routine, we
fit Sersic (r^{1/n}) and exponential models to their bulge and disk components
respectively. Dividing the galaxies into three subsamples according to the
X-ray luminosities of their parent groups, we compare their photometric
properties. Galaxies in X-ray luminous groups tend to be larger and more
luminous than those in groups with undetected or low X-ray luminosities, but no
significant differences in n are seen. Both normal and dwarf elliptical
galaxies in the central regions of groups are found to have cuspier profiles
than their counterparts in group outskirts.
  Structural differences between dwarf and normal elliptical galaxies are
apparent in terms of an offset between their ``Photometric Planes'' in the
space of n, r_e and mu_0. Dwarf ellipticals are found to populate a surface,
with remarkably low scatter, in this space with significant curvature, somewhat
similar to the surfaces of constant entropy proposed by Marquez etal (2001).
Normal ellipticals are offset from this distribution in a direction of higher
specific entropy. This may indicate that the two populations are distinguished
by the action of galaxy merging on larger galaxies.

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The categories of this paper are: nucl-th
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The categories of this paper are: hep-th
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The categories of this paper are: econ
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: quant-ph
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The categories of this paper are: supr-con
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The categories of this paper are: nucl-ex
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The categories of this paper are: ao-sci
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The categories of this paper are: q-fin
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The categories of this paper are: cond-mat
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The categories of this paper are: cs
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The categories of this paper are: acc-phys
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The categories of this paper are: solv-int
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The categories of this paper are: chao-dyn
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The categories of this paper are: adap-org