Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ultraluminous X-ray Sources, High Redshift QSOs and Active Galaxies   It is shown that all of the 32 point X-ray sources which lie within about 10'
of the centre of nearby galaxies, and which have so far been optically
identified are high redshift objects - AGN or QSOs. Thus the surface density of
these QSOs p similar or equal to 0.1 per square arc minute. Some of them were
originally discovered as X-ray sources and classified as ultraluminous X-ray
sources (ULXs), nearly all of which lie near the centers of active galaxies. We
demonstrate that this concentration around galactic nuclei is of high
statistical significance: the probabiliy that p that they are accidental lies
in the range one in a thousand to one in ten thousand, and apparently this
excess cannot be accounted for by microlensing.

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The categories of this paper are: dg-ga
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The categories of this paper are: patt-sol
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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: cond-mat
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The categories of this paper are: gr-qc
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The categories of this paper are: hep-lat
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The categories of this paper are: solv-int
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The categories of this paper are: math-ph
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The categories of this paper are: q-fin
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The categories of this paper are: nlin
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The categories of this paper are: cmp-lg
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The categories of this paper are: stat
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The categories of this paper are: bayes-an
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The categories of this paper are: plasm-ph
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The categories of this paper are: q-alg