Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Canada-France Redshift Survey VII: Optical counterparts of
  microJansky radiosources   Deep imaging and spectroscopy have been carried out for optical counterparts
of a complete sample of S$>$16 $\mu$Jy radiosources during the course of the
Canada-France Redshift Survey (CFRS). All 36 sources but two have been
optically identified, and spectra have been obtained for 23 of them. The
objects brighter than $I_{AB}<$22.5 for which we have spectra reveal three
populations dominating the $\mu$Jy radio counts: z$>$0.7 early-type galaxies
with radio emission powered by an AGN, intermediate redshift post-starburst
galaxies, and lower redshift blue emission-line objects. From their radio and
optical properties, it is argued that the 11 objects fainter than $I_{AB}>$22.5
are mostly at z$>$1, and one half of them are probably early-type galaxies. We
conclude that $\sim$40 per cent of the $\mu$Jy sources are likely to be at z
$>$1. Between one third and one half of the luminous ellipticals in this field
beyond z = 0.7 show moderately powerful radio emission (P $\sim$ 5 10$^{23}$ W
Hz$^{-1}$) which is at least 10 times more powerful than seen in local samples,
and probably reflects evolution of the activity in their nuclei. Only one
classical starburst galaxy is identified in the sample; the rest of the blue
emission-line objects show optical and radio activity more typical of low power
AGNs than starbursts. The number of post-starbursts at $\mu$Jy levels is
considerably higher than the surface density of mJy starburst galaxies,
suggesting the latter are the parent population of the former. While starburst
galaxies are considered to be major contributors to the mJy radiosources
counts, the majority of the $\mu$Jy radio sources appear to be related to AGN
activity rather than to normal star

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The categories of this paper are: patt-sol
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The categories of this paper are: nlin
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The categories of this paper are: acc-phys
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The categories of this paper are: q-fin
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The categories of this paper are: physics
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The categories of this paper are: alg-geom
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The categories of this paper are: comp-gas
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The categories of this paper are: cmp-lg
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The categories of this paper are: mtrl-th
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The categories of this paper are: quant-ph
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The categories of this paper are: q-alg
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The categories of this paper are: gr-qc
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The categories of this paper are: ao-sci
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The categories of this paper are: plasm-ph
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The categories of this paper are: econ
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The categories of this paper are: solv-int