Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: X-ray selected AGN in groups at redshifts z~1   We explore the role of the group environment in the evolution of AGN at the
redshift interval 0.7<z<1.4, by combining deep Chandra observations with
extensive optical spectroscopy from the All-wavelength Extended Groth strip
International Survey (AEGIS). The sample consists of 3902 optical sources and
71 X-ray AGN. Compared to the overall optically selected galaxy population,
X-ray AGN are more frequently found in groups at the 99% confidence level. This
is partly because AGN are hosted by red luminous galaxies, which are known to
reside, on average, in dense environments. Relative to these sources, the
excess of X-ray AGN in groups is significant at the 91% level only. Restricting
the sample to 0.7<z<0.9 and M_B<-20mag in order to control systematics we find
that X-ray AGN represent (4.7\pm1.6) and (4.5\pm1.0)% of the optical galaxy
population in groups and in the field respectively. These numbers are
consistent with the AGN fraction in low redshift clusters, groups and the
field. The results above, although affected by small number statistics, suggest
that X-ray AGN are spread over a range of environments, from groups to the
field, once the properties of their hosts (e.g. colour, luminosity) are
accounted for. There is also tentative evidence, significant at the 98% level,
that the field produces more X-ray luminous AGN compared to groups, extending
similar results at low redshift to z~1. This trend may be because of either
cold gas availability or the nature of the interactions occurring in the denser
group environment (i.e. prolonged tidal encounters).

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The categories of this paper are: cmp-lg
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The categories of this paper are: chem-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: gr-qc
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The categories of this paper are: quant-ph
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The categories of this paper are: nlin
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The categories of this paper are: bayes-an
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The categories of this paper are: eess
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The categories of this paper are: acc-phys
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The categories of this paper are: patt-sol
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The categories of this paper are: supr-con
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-th
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The categories of this paper are: funct-an
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The categories of this paper are: hep-lat
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The categories of this paper are: q-alg