Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Molecular Einstein Ring at z=4.12: Imaging the Dynamics of a Quasar
  Host Galaxy Through a Cosmic Lens   We present high-resolution (0.3") Very Large Array (VLA) imaging of the
molecular gas in the host galaxy of the high redshift quasar PSS J2322+1944
(z=4.12). These observations confirm that the molecular gas (CO) in the host
galaxy of this quasar is lensed into a full Einstein ring, and reveal the
internal dynamics of the molecular gas in this system. The ring has a diameter
of ~1.5", and thus is sampled over ~20 resolution elements by our observations.
Through a model-based lens inversion, we recover the velocity gradient of the
molecular reservoir in the quasar host galaxy of PSS J2322+1944. The Einstein
ring lens configuration enables us to zoom in on the emission and to resolve
scales down to ~1 kpc. From the model-reconstructed source, we find that the
molecular gas is distributed on a scale of 5 kpc, and has a total mass of
M(H2)=1.7 x 10^10 M_sun. A basic estimate of the dynamical mass gives M_dyn =
4.4 x 10^10 (sin i)^-2 M_sun, that is, only ~2.5 times the molecular gas mass,
and ~30 times the black hole mass (assuming that the dynamical structure is
highly inclined). The lens configuration also allows us to tie the optical
emission to the molecular gas emission, which suggests that the active galactic
nucleus (AGN) does reside within, but not close to the center of the molecular
reservoir. Together with the (at least partially) disturbed structure of the
CO, this suggests that the system is interacting. Such an interaction, possibly
caused by a major `wet' merger, may be responsible for both feeding the quasar
and fueling the massive starburst of 680 M_sun/yr in this system, in agreement
with recently suggested scenarios of quasar activity and galaxy assembly in the
early universe.

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The categories of this paper are: adap-org
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The categories of this paper are: hep-ex
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The categories of this paper are: funct-an
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The categories of this paper are: cond-mat
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The categories of this paper are: atom-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: acc-phys
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The categories of this paper are: nucl-ex
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The categories of this paper are: cs
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The categories of this paper are: cmp-lg
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The categories of this paper are: comp-gas
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The categories of this paper are: math
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The categories of this paper are: q-fin
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The categories of this paper are: q-bio
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The categories of this paper are: quant-ph
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The categories of this paper are: q-alg