Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Radio Observations of the 13hr XMM/ROSAT Deep X-ray Survey Area   In order to determine the relationship between the faint X-ray and faint
radio source populations, and hence to help understand the X-ray and radio
emission mechanisms in those faint source populations, we have made a deep
1.4GHz Very Large Array radio survey of the 13h +38deg XMM/ROSAT X-ray Survey
Area. From a combined data set of 10hours B configuration data and 14hours A
configuration data, maps with 3.35'' resolution and a noise limit of 7.5uJy
were constructed. A complete sample of 449 sources was detected within a 30'
diameter region above a 4sigma detection limit of 30uJy, at the map centre,
making this one of the deepest radio surveys at this frequency. The
differential source count shows a significant upturn at sub-milliJansky flux
densities, similar to that seen in other deep surveys at 1.4GHz (eg the Phoenix
survey), but larger than that seen in the HDF which may have been selected to
be under-dense. This upturn is well modelled by the emergence of a population
of medium redshift starforming galaxies which dominate at faint flux densities.
The brighter source counts are well modelled by AGNs.

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The categories of this paper are: hep-ex
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The categories of this paper are: math
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The categories of this paper are: econ
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The categories of this paper are: hep-lat
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The categories of this paper are: nucl-th
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The categories of this paper are: quant-ph
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The categories of this paper are: q-fin
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The categories of this paper are: chem-ph
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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: physics
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The categories of this paper are: hep-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: q-alg
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-th