Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Galactic disc phase spirals at different Galactic positions revealed
  by Gaia and LAMOST data   We have investigated the distributions of stellar azimuthal and radial
velocity components $V_{\Phi}$ and $V_{R}$ in the vertical position-velocity
plane $Z$-$V_{Z}$ across the Galactic disc of $6.34 \lesssim R \lesssim
12.34$\,kpc and $|\Phi| \lesssim 7.5^{\circ}$ using a Gaia and Gaia-LAMOST
sample of stars. As found in previous works, the distributions exhibit
significant spiral patterns. The $V_{R}$ distributions also show clear
quadrupole patterns, which are the consequence of the well-known tilt of the
velocity ellipsoid. The observed spiral and quadrupole patterns in the phase
space plane vary strongly with radial and azimuthal positions. The phase
spirals of $V_{\Phi}$ become more and more relaxed as $R$ increases. The spiral
patterns of $V_{\Phi}$ and $V_{R}$ and the quadrupole patterns of $V_{R}$ are
strongest at $-2^{\circ} < \Phi < 2^{\circ}$ but negligible at $4^{\circ} <
\Phi < 6^{\circ}$ and $-6^{\circ} < \Phi < -4^{\circ}$. Our results suggest an
external origin of the phase spirals. In this scenario, the intruder, most
likely the previously well-known Sagittarius dwarf galaxy, passed through the
Galactic plane in the direction towards either Galactic center or anti-center.
The azimuthal variations of the phase spirals also help us constrain the
passage duration of the intruder. A detailed model is required to reproduce the
observed radial and azimuthal variations of the phase spirals of $V_{\Phi}$ and
$V_{R}$.

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The categories of this paper are: q-fin
4
The categories of this paper are: cond-mat
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The categories of this paper are: hep-lat
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The categories of this paper are: econ
34
The categories of this paper are: chem-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: acc-phys
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The categories of this paper are: q-alg
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The categories of this paper are: math
3
The categories of this paper are: physics
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The categories of this paper are: gr-qc
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The categories of this paper are: funct-an
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The categories of this paper are: nlin
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The categories of this paper are: plasm-ph
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The categories of this paper are: solv-int
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The categories of this paper are: hep-th