Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Detailed Structural Decomposition of Galaxy Images   We present a two-dimensional (2-D) fitting algorithm (GALFIT) designed to
extract structural components from galaxy images, with emphasis on closely
modeling light profiles of spatially well-resolved, nearby galaxies observed
with the Hubble Space Telescope. Our algorithm improves on previous techniques
in two areas, by being able to simultaneously fit a galaxy with an arbitrary
number of components, and with optimization in computation speed, suited for
working on large galaxy images. We use 2-D models such as the ``Nuker'' law,
the Sersic (de Vaucouleurs) profile, an exponential disk, and Gaussian or
Moffat functions. The azimuthal shapes are generalized ellipses that can fit
disky and boxy components. Many galaxies with complex isophotes, ellipticity
changes, and position-angle twists can be modeled accurately in 2-D. When
examined in detail, we find that even simple-looking galaxies generally require
at least three components to be modeled accurately, rather than the one or two
components more often employed. We illustrate this by way of 7 case studies,
which include regular and barred spiral galaxies, highly disky lenticular
galaxies, and elliptical galaxies displaying various levels of complexities. A
useful extension of this algorithm is to accurately extract nuclear point
sources in galaxies. We compare 2-D and 1-D extraction techniques on simulated
images of galaxies having nuclear slopes with different degrees of cuspiness,
and we then illustrate the application of the program to several examples of
nearby galaxies with weak nuclei.

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The categories of this paper are: quant-ph
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
10
The categories of this paper are: q-bio
32
The categories of this paper are: atom-ph
14
The categories of this paper are: math-ph
1
The categories of this paper are: cs
30
The categories of this paper are: q-alg
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The categories of this paper are: solv-int
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The categories of this paper are: acc-phys
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The categories of this paper are: adap-org
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The categories of this paper are: plasm-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: patt-sol
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The categories of this paper are: math
0
The categories of this paper are: hep-ph