Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spectroscopic Redshifts to z > 2 for Optically Obscured Sources
  Discovered with the Spitzer Space Telescope   We have surveyed a field covering 9.0 degrees^2 within the NOAO Deep
Wide-Field Survey region in Bootes with the Multiband Imaging Photometer on the
Spitzer Space Telescope (SST) to a limiting 24 um flux density of 0.3 mJy.
Thirty one sources from this survey with F(24um) > 0.75 mJy which are optically
very faint (R > 24.5 mag) have been observed with the low-resolution modules of
the Infrared Spectrograph on SST. Redshifts derived primarily from strong
silicate absorption features are reported here for 17 of these sources; 10 of
these are optically invisible (R > 26 mag), with no counterpart in B_W, R, or
I. The observed redshifts for 16 sources are 1.7 < z < 2.8. These represent a
newly discovered population of highly obscured sources at high redshift with
extreme infrared to optical ratios. Using IRS spectra of local galaxies as
templates, we find that a majority of the sources have mid-infrared spectral
shapes most similar to ultraluminous infrared galaxies powered primarily by
AGN. Assuming the same templates also apply at longer wavelengths, bolometric
luminosities exceed 10^13 L(solar).

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The categories of this paper are: plasm-ph
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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: q-alg
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The categories of this paper are: nucl-th
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: nlin
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The categories of this paper are: quant-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: cs
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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: math
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The categories of this paper are: econ