Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Very Red and Extremely Red Galaxies in the Fields of z ~ 1.5 Radio-Loud
  Quasars   We previously identified an excess of mostly red galaxies around 31 RLQs at
z=1-2. These fields have an ERO (extremely red object, R-K>6) density 2.7 times
higher than the field. Assuming the EROs are passively evolved galaxies at the
quasar redshifts, they have characteristic luminosities of only ~L^*. We also
present new observations of four z~1.54 RLQ fields: (1) Wide-field J & Ks data
confirm an Abell richness ~2 excess within 140" of Q0835+580 but an excess only
within 50" of Q1126+101. (2) In 3 fields we present deep narrow-band redshifted
H-alpha observations. We detect five candidate galaxies at the quasar
redshifts, a surface density 2.5x higher than the field. (3) SCUBA sub-mm
observations of 3 fields detect 2 quasars and 2 galaxies with SEDs best fit as
highly reddened galaxies at the quasar z. (4) H-band adaptive optics (AO)
imaging is used to estimate redshifts for 2 red, bulge-dominated galaxies using
the Kormendy relation. Both have structural redshifts foreground to the quasar,
but these are not confirmed by photometric redshifts, possibly because their
optical photometry is corrupted by scattered light from the AO guidestar. (5)
We use quantitative SED fits to constrain the photometric redshifts z_ph for
some galaxies. Most galaxies near Q0835+580 are consistent with being at its
redshift, including a candidate very old passively evolving galaxy. Many very &
extremely red objects have z_ph z_q, and dust reddening is required to fit most
of them, including many objects whose fits also require relatively old stellar
populations. Large reddenings of E(B-V)~0.6 are required to fit four J-K
selected EROs, though all but one of them have best-fit z_ph>z_q. These objects
may represent a population of dusty high-z galaxies underrepresented in
optically selected samples. (Abridged)

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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-alg
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The categories of this paper are: physics
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The categories of this paper are: hep-th
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The categories of this paper are: plasm-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-lat
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The categories of this paper are: cs
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The categories of this paper are: cond-mat
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The categories of this paper are: hep-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: nlin
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The categories of this paper are: stat
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The categories of this paper are: funct-an