Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A systematic study of soft X-ray pulse profiles of magnetars in
  quiescence   Magnetars are neutron stars with extremely high surface magnetic fields. They
show diverse X-ray pulse profiles in the quiescent state. We perform a
systematic Fourier analysis of their soft X-ray pulse profiles. We find that
most magnetars have a single-peaked profile and hence have low amplitudes of
the second Fourier harmonics (A2). On the other hand, the pulsed fraction (PF)
spreads over a wide range. We compared the results with theoretical profiles
assuming various surface hotspot asymmetries, viewing geometries, and beaming
functions. We found that a single value of the intensity ratio r between two
antipodal hotspots is unable to reproduce the observed distribution of A2 and
PF for all magnetars. The inferred r is probably anticorrelated with the
thermal luminosity, implying that high-luminosity magnetars tend to have two
symmetric hotspots. Our results are consistent with theoretical predictions,
for which the existence of an evolving toroidal magnetic field breaks the
symmetry of the surface temperature.

21
The categories of this paper are: adap-org
34
The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
8
The categories of this paper are: hep-ex
19
The categories of this paper are: eess
18
The categories of this paper are: econ
16
The categories of this paper are: stat
0
The categories of this paper are: hep-ph
2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
29
The categories of this paper are: funct-an
10
The categories of this paper are: q-bio
31
The categories of this paper are: ao-sci
26
The categories of this paper are: bayes-an