Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The nature of the 3CR radio galaxies at z=1   We present evidence that the 3CR radio galaxies at redshift one are already
very massive, highly dynamically evolved galaxies, which lie at the heart of
(proto--)cluster environments. Since nearby 3CR double radio sources are
generally found in more isolated surroundings, the galactic environments of
these galaxies must change dramatically with redshift. Therefore, the original
`uniform population, closed box' interpretation of the infrared K--magnitude vs
redshift relationship no longer appears valid. We propose a new interpretation:
the powerful radio galaxies selected at high and low redshift have different
evolutionary histories, but must contain a similar mass of stars, a few times
10-to-the-power-11 solar masses, and so conspire to produce the `passively
evolving' K-z relation observed. We discuss this model in the context of the
current understanding of powerful radio sources and, in light of this new
model, we compare the K-z relation of the 3CR galaxies with those derived for
lower power radio galaxies and for brightest cluster galaxies.

33
The categories of this paper are: plasm-ph
4
The categories of this paper are: cond-mat
0
The categories of this paper are: hep-ph
14
The categories of this paper are: math-ph
24
The categories of this paper are: dg-ga
3
The categories of this paper are: physics
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The categories of this paper are: atom-ph
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The categories of this paper are: bayes-an
10
The categories of this paper are: q-bio
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The categories of this paper are: econ
11
The categories of this paper are: hep-lat
28
The categories of this paper are: alg-geom
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The categories of this paper are: solv-int
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The categories of this paper are: eess
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The categories of this paper are: q-fin
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The categories of this paper are: q-alg