Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Orbital and Spin Phase-Resolved Spectroscopy of the Intermediate Polar
  EX Hya Using XMM-Newton Data   We present for the first time orbital phase-resolved spectra of an
intermediate polar (IP), EX Hya, together with the spin phase-resolved spectra
during two different epochs using the X-ray Multi-Mirror Mission, European
Photon Imaging Camera (pn instrument). We find that the source at the two
epochs has the same X-ray luminosity of $\sim$ 6.5 $\times$ 10$^{31}$ erg
s$^{-1}$. We detect spectral variations between the 2000 and 2003 observations
of the source. We fitted the spectrum using a neutral hydrogen absorption model
with or without covering fraction together with Gaussians for emission lines,
two collisional equilibrium plasma emission models (MEKAL) and a cooling-flow
plasma emission model (VMCFLOW). We find that two of the three emission
components ($kT$=0.6-0.8 keV and $kT$=1.3-1.7 keV) fitted by the MEKAL models
are almost constant over the spin and orbital phases and also over the two
different epochs with the normalisation varying directly proportional to the
flux when the data are folded according to the orbital and spin phase
indicating that the slight variation may be due to occultation. The emission
modeled by the VMCFLOW changes over the spin and orbital phases and the 2000
and 2003 observations reveal two different ranges of temperatures (3-33 and
8-61 keV respectively) that model the shock zone in the accretion column/s. The
ratios of the spin maximum to minimum and the orbital maximum to minimum
spectra along with the increase in the plasma temperatures indicate that the
spectrum gets harder in the minimum phases of both orbital and spin periods. In
the 2003 observation, a 6.4 keV fluorescent Fe emission line is present at the
orbital minima in a range of phases from 0.9 to 1.3 and it is absent otherwise.
This indicates that there is reflection from the disc most likely from a large
bulge at the accretion impact zone.

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The categories of this paper are: cond-mat
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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: nucl-ex
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The categories of this paper are: stat
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The categories of this paper are: bayes-an
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The categories of this paper are: eess
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The categories of this paper are: econ
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The categories of this paper are: chem-ph
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The categories of this paper are: nlin
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The categories of this paper are: funct-an
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The categories of this paper are: hep-lat
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-th
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The categories of this paper are: acc-phys
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The categories of this paper are: gr-qc