Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The coincidence and angular clustering of Chandra and SCUBA sources   We explore the relationship between the hard X-ray and sub-mm populations
using deep Chandra observations of a large, contiguous SCUBA survey. In
agreement with other recent findings, we confirm that the direct overlap is
small. Of the 17 sub-mm sources detected in this field at 850 microns, only one
is coincident with a Chandra source. The resulting limits imply that the
majority of SCUBA sources are not powered by AGN, unless the central engine is
obscured by Compton-thick material with a low (<1 per cent) scattered
component. Furthermore, since Chandra detects only ~5 per cent of SCUBA
sources, the typical obscuration would need to be almost isotropic. The X-ray
upper limits are so strong that in most cases we can also rule out a starburst
SED at low redshift, suggesting that the majority of SCUBA sources lie at z>1
even if they are purely starburst galaxies. Despite the low detection rate, we
find evidence for strong angular clustering between the X-ray and sub-mm
populations. The implication is that AGN and SCUBA sources trace the same
large-scale structure but do not generally coincide. If bright sub-mm sources
represent massive elliptical galaxies in formation, we suggest that (for a
given galaxy) the major episode of star-formation must be distinct from the
period of observable quasar activity.

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The categories of this paper are: bayes-an
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The categories of this paper are: adap-org
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The categories of this paper are: patt-sol
16
The categories of this paper are: stat
9
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: chao-dyn
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The categories of this paper are: q-fin
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The categories of this paper are: hep-ex
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The categories of this paper are: hep-ph
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The categories of this paper are: hep-th
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The categories of this paper are: physics
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The categories of this paper are: math-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: mtrl-th
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The categories of this paper are: plasm-ph