Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Towards a comprehensive picture of powerful quasars, their host galaxies
  and quasar winds at z ~ 0.5   Luminous type-2 quasars in which the glow from the central black hole is
obscured by dust are ideal targets for studying their host galaxies and the
quasars' effect on galaxy evolution. Such feedback appears ubiquitous in
luminous obscured quasars where high velocity ionized nebulae have been found.
We present rest-frame yellow-band (~5000 Angstroms) observations using the
Hubble Space Telescope for a sample of 20 luminous quasar host galaxies at 0.2
< z < 0.6 selected from the Sloan Digital Sky Survey. For the first time, we
combine host galaxy observations with geometric measurements of quasar
illumination using blue-band HST observations and [OIII] integral field unit
observations probing the quasar winds. The HST images reveal bright merger
signatures in about half the galaxies; a significantly higher fraction than in
comparison inactive ellipticals. We show that the host galaxies are primarily
bulge-dominated, with masses close to M*, but belong to < 30% of elliptical
galaxies that are highly star-forming at z ~ 0.5. Ionized gas signatures are
uncorrelated with faint stellar disks (if present), confirming that the ionized
gas is not concentrated in a disk. Scattering cones and [OIII] ionized gas
velocity field are aligned with the forward scattering cones being co-spatial
with the blue-shifted side of the velocity field, suggesting the high velocity
gas is indeed photo-ionized by the quasar. Based on the host galaxies' high
star-formation rates and bright merger signatures, we suggest that this
low-redshift outbreak of luminous quasar activity is triggered by recent minor
mergers. Combining these novel observations, we present new quasar unification
tests, which are in agreement with expectations of the orientation-based
unification model for quasars.

18
The categories of this paper are: econ
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
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The categories of this paper are: patt-sol
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The categories of this paper are: nucl-th
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The categories of this paper are: adap-org
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The categories of this paper are: hep-lat
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The categories of this paper are: alg-geom
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The categories of this paper are: funct-an
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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: chem-ph
1
The categories of this paper are: cs
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The categories of this paper are: nlin
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The categories of this paper are: gr-qc
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The categories of this paper are: q-alg