Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Luminosity functions for galaxies and quasars in the Spitzer Wide-Area
  Infrared Extra-galactic (SWIRE) Legacy survey   We construct rest-frame luminosity functions at 3.6, 4.5, 5.8, 8 and 24
microns over the redshift range 0<z<2 for galaxies and 0<z<4 for optical QSOs,
using optical and infrared data from the Spitzer Wide-area InfraRed
Extragalactic survey. The 3.6 and 4.5 micron galaxy LFs show evidence for
moderate positive luminosity evolution up to z~1.5, consistent with the passive
ageing of evolved stellar populations. Their comoving luminosity density was
found to evolve passively, gradually increasing out to z~0.5-1 but flattening,
or even declining, at higher redshift. Conversely, the 24 micron galaxy LF,
which is more sensitive to obscured star formation and/or AGN activity,
undergoes strong positive evolution, with the derived IR energy density and SFR
density proportional to (1+z)^gamma with gamma=4.5^{+0.7}_{-0.6} and the
majority of this evolution occurring since z~1. Optical QSOs, however, show
positive luminosity evolution in all bands, out to the highest redshifts
(3<z<4). Modelling as L* proportional to (1+z)^gamma gave
gamma=1.3^{+0.1}_{-0.1} at 3.6 micron, gamma=1.0^{+0.1}_{-0.1} at 4.5 micron
and stronger evolution at the longer wavelengths (5.8, 8 and 24 micron), of
gamma~3. Comparison of the galaxy LFs to predictions from a semi-analytic model
based on CDM indicate that an IMF skewed towards higher mass star formation in
bursts compared to locally is preferred. As a result the currently inferred
massive star formation rates in distant sub-mm sources may require substantial
downwards revision.

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The categories of this paper are: nlin
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The categories of this paper are: chao-dyn
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The categories of this paper are: gr-qc
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The categories of this paper are: math
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The categories of this paper are: q-alg
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The categories of this paper are: supr-con
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The categories of this paper are: stat
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The categories of this paper are: math-ph
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The categories of this paper are: adap-org
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The categories of this paper are: alg-geom
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The categories of this paper are: cmp-lg
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The categories of this paper are: q-bio
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-th
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-ph