Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An HST Morphological Survey of Faint EROs   We present the results from a survey for Extremely Red Objects (EROs) in
deep, high resolution optical images taken from the Hubble Space Telescope
(HST) Medium Deep Survey. We have surveyed 35 deep F814W HST/WFPC2 fields in
the near-infrared to a typical depth of K~20. From a total area of 206 arcmin^2
and to a limit of K=20.0 we identify 224 EROs ((1.14+/-0.08) arcmin^-2) with
(I_{814}-K)=>4.0 and 83 ((0.41+/-0.05) arcmin^-2) with (I_{814}-K)=>5.0. We
find that the slope of the number counts of the (I_{814}-K)=>4.0 EROs flattens
beyond K~19, in line with results from previous surveys, and the typical
colours of the EROs become redder beyond the break magnitude. We
morphologically classify our ERO sample using visual and quantitative schemes
and find that 35% of our sample exhibit clear disk components, 15% are
disturbed or irregular, a further 30% are either spheroidal or compact and the
remaining 20% are unclassifiable. Using a quantitative measure of morphology,
we find that the ERO morphological distribution evolves across the break in
their counts, such that low concentration (disk-like) galaxies decline. We
relate the morphological and colour information for our EROs and conclude that
those EROs morphologically classified as bulges do indeed possess SEDs
consistent with passive stellar populations; while EROs with dusty star-forming
SEDs are mostly associated with disk-like and peculiar galaxies. However, ~30%
of disk EROs reside in the passive region of I/J/K colour-colour space. These
could be either genuinely passive systems, lower redshift contaminants to the
high-z ERO population, or systems with composite star-forming and passive SEDs.

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The categories of this paper are: hep-lat
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The categories of this paper are: cond-mat
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The categories of this paper are: mtrl-th
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The categories of this paper are: hep-ex
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The categories of this paper are: atom-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: funct-an
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The categories of this paper are: gr-qc
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The categories of this paper are: q-fin
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The categories of this paper are: eess
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The categories of this paper are: q-bio
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The categories of this paper are: patt-sol
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The categories of this paper are: alg-geom
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The categories of this paper are: math
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The categories of this paper are: adap-org
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The categories of this paper are: hep-th