Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Probing the Interstellar Dust towards the Galactic Centre: Dust
  Scattering Halo around AX J1745.6-2901   AX J1745.6-2901 is an X-ray binary located at only 1.45 arcmin from Sgr A*,
showcasing a strong X-ray dust scattering halo. We combine Chandra and
XMM-Newton observations to study the halo around this X-ray binary. Our study
shows two major thick dust layers along the line of sight (LOS) towards AX
J1745.6-2901. The LOS position and $N_{H}$ of these two layers depend on the
dust grain models with different grain size distribution and abundances. But
for all the 19 dust grain models considered, dust Layer-1 is consistently found
to be within a fractional distance of 0.11 (mean value: 0.05) to AX
J1745.6-2901 and contains only (19-34)% (mean value: 26%) of the total LOS
dust. The remaining dust is contained in Layer-2, which is distributed from the
Earth up to a mean fractional distance of 0.64. A significant separation
between the two layers is found for all the dust grain models, with a mean
fractional distance of 0.31. Besides, an extended wing component is discovered
in the halo, which implies a higher fraction of dust grains with typical sizes
$\lesssim$ 590 \AA\ than considered in current dust grain models. Assuming AX
J1745.6-2901 is 8 kpc away, dust Layer-2 would be located in the Galactic disk
several kpc away from the Galactic Centre (GC). The dust scattering halo biases
the observed spectrum of AX J1745.6-2901 severely in both spectral shape and
flux, and also introduces a strong dependence on the size of the instrumental
point spread function and the source extraction region. We build Xspec models
to account for this spectral bias, which allow us to recover the intrinsic
spectrum of AX J1745.6-2901 free from dust scattering opacity. If dust Layer-2
also intervenes along the LOS to Sgr A* and other nearby GC sources, a
significant spectral correction for the dust scattering opacity would be
necessary for all these GC sources.

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The categories of this paper are: supr-con
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The categories of this paper are: cmp-lg
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The categories of this paper are: econ
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The categories of this paper are: eess
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The categories of this paper are: math-ph
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The categories of this paper are: q-bio
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The categories of this paper are: math
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The categories of this paper are: chao-dyn
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The categories of this paper are: cs
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The categories of this paper are: physics
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The categories of this paper are: solv-int
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The categories of this paper are: chem-ph
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The categories of this paper are: q-fin
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The categories of this paper are: hep-th
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The categories of this paper are: cond-mat
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The categories of this paper are: ao-sci