Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: PS18kh: A New Tidal Disruption Event with a Non-Axisymmetric Accretion
  Disk   We present the discovery of PS18kh, a tidal disruption event (TDE) discovered
at the center of SDSS J075654.53+341543.6 ($d\simeq322$ Mpc) by the Pan-STARRS
Survey for Transients. Our dataset includes pre-discovery survey data from
Pan-STARRS, the All-Sky Automated Survey for Supernovae (ASAS-SN), and the
Asteroid Terrestrial-impact Last Alert System (ATLAS) as well as high-cadence,
multi-wavelength follow-up data from ground-based telescopes and Swift,
spanning from 56 days before peak light until 75 days after. The optical/UV
emission from PS18kh is well-fit as a blackbody with temperatures ranging from
$T\simeq12000$ K to $T\simeq25000$ K and it peaked at a luminosity of
$L\simeq8.8\times10^{43}$ ergs s$^{-1}$. PS18kh radiated
$E=(3.45\pm0.22)\times10^{50}$ ergs over the period of observation, with
$(1.42\pm0.20)\times10^{50}$ ergs being released during the rise to peak.
Spectra of PS18kh show a changing, boxy/double-peaked H$\alpha$ emission
feature, which becomes more prominent over time. We use models of
non-axisymmetric accretion disks to describe the profile of the H$\alpha$ line
and its evolution. We find that at early times the high accretion rate leads
the disk to emit a wind which modifies the shape of the line profile and makes
it bell-shaped. At late times, the wind becomes optically thin, allowing the
non-axisymmetric perturbations to show up in the line profile. The
line-emitting portion of the disk extends from $r_{\rm in}\sim60r_{\rm g}$ to
an outer radius of $r_{\rm out}\sim1400r_{\rm g}$ and the perturbations can be
represented either as an eccentricity in the outer rings of the disk or as a
spiral arm in the inner disk.

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The categories of this paper are: comp-gas
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The categories of this paper are: q-fin
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The categories of this paper are: econ
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The categories of this paper are: alg-geom
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-lat
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The categories of this paper are: q-alg
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The categories of this paper are: patt-sol
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The categories of this paper are: ao-sci
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The categories of this paper are: math-ph
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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: eess
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The categories of this paper are: acc-phys
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The categories of this paper are: hep-th
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The categories of this paper are: supr-con