Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observational evidence that massive cluster galaxies were forming stars
  at z~2.5 and did not grow in mass at later times   Using Spitzer 3.6 micron data we derived the luminosity function and the mass
function of galaxies in five z>1.4 clusters selected to have a firm
intracluster medium detection. The five clusters differ in richness
(ISCSJ1438.1+3414 and XMMXCSJ2215.9-1738 are twice as rich as ISCSJ1432.4+3250,
IDCSJ1426.5+3508, and JKCS041) and morphological appareance. At the median
redshift z=1.5, from the 150 member galaxies of the five clusters, we derived a
characteristic magnitude of 16.92+/-0.13 in the [3.6] band and a characteristic
mass of lgM*=11.30+/-0.05 Msol. We find that the characteristic luminosity and
mass does not evolve between z=1 and 1.4<z<1.8, directly ruling out ongoing
mass assembly between these epochs because massive galaxies are already present
up to z=1.8. Lower-redshift build-up epochs have already been ruled out by
previous works, leaving only z>1.8 as a possible epoch for the mass build up.
However, the observed values of m^* at very high redshift are too bright for
galaxies without any star formation immediately preceding the observed redshift
and therefore imply a star formation episode not earlier than z_f=2.5. For the
first time, mass/luminosity functions are able to robustly distinguish tiny
differences between formation redshifts and to set {\it upper} limits to the
epoch of the last star-formation episode.

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The categories of this paper are: math-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: patt-sol
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The categories of this paper are: comp-gas
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The categories of this paper are: ao-sci
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The categories of this paper are: gr-qc
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The categories of this paper are: acc-phys
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The categories of this paper are: adap-org
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-ex
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The categories of this paper are: chao-dyn
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The categories of this paper are: dg-ga
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The categories of this paper are: physics
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The categories of this paper are: bayes-an
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The categories of this paper are: math
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The categories of this paper are: q-fin