Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Constraining the Flaring Region of Sagittarius A* By 1.3mm VLBI
  Measurements   We use a model of an accretion flow coupled with an emergent flare to
interpret the latest 1.3mm VLBI measurements for Sagittarius A*. The visibility
data constrained the distances from the flare center to the black hole center
as $d_{\rm EW}\lesssim20{\rm R_g}$ and $d_{\rm NS}\lesssim80{\rm R_g}$ in the
East-West and North-South directions, respectively. If interpreted by the
hot-spot model, the flare was preferred to pass in front of the black hole at a
radius much larger than $d_{\rm EW}$. If interpreted by the episodic jet
launched from a nearly edge-on hot accretion flow, the flare was preferred to
be ejected with $\theta_{\rm j}\gtrsim40^\circ$ off the black hole rotating
axis. This method can be generalized to help us understand future
sub-millimeter VLBI observations, and study the millimeter/sub-millimeter
variabilities in the vicinity of the Galactic Center supermassive black hole.

25
The categories of this paper are: patt-sol
37
The categories of this paper are: supr-con
26
The categories of this paper are: bayes-an
17
The categories of this paper are: q-fin
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The categories of this paper are: acc-phys
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The categories of this paper are: econ
7
The categories of this paper are: hep-th
28
The categories of this paper are: alg-geom
3
The categories of this paper are: physics
36
The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
33
The categories of this paper are: plasm-ph
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The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
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The categories of this paper are: funct-an
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The categories of this paper are: nlin