Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ultra-Luminous Sources in Nearby Galaxies   I briefly review much of the X-ray and optical data on the nature of the ULXs
in nearby galaxies. I present new results on radio emission, finding that the
radio is usually rather luminous and extended. I review the X-ray data on
timing and spectra. There is no direct evidence in the X-ray data for either
geometric or relativistic beaming and in 4 objects direct evidence against
beaming. I argue that the X-ray timing and spectral properties of these objects
are, in general, not good analogs of AGN or galactic black holes and that the
ULX may represent a new mode of accretion only rarely seen in other objects.

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The categories of this paper are: hep-lat
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The categories of this paper are: math-ph
16
The categories of this paper are: stat
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-th
36
The categories of this paper are: cmp-lg
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The categories of this paper are: acc-phys
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The categories of this paper are: mtrl-th
4
The categories of this paper are: cond-mat
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The categories of this paper are: eess
1
The categories of this paper are: cs
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The categories of this paper are: adap-org
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The categories of this paper are: econ
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The categories of this paper are: chao-dyn
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-ex