Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Luminosity dependence of the cyclotron line and evidence for the
  accretion regime transition in V 0332+53   We report on the analysis of NuSTAR observations of the Be-transient X-ray
pulsar V 0332+53 during the giant outburst in 2015 and another minor outburst
in 2016. We confirm the cyclotron-line energy-luminosity correlation previously
reported in the source and the line energy decrease during the giant outburst.
Based on 2016 observations, we find that a year later the line energy has
increased again essentially reaching the pre-outburst values. We discuss this
behaviour and conclude that it is likely caused by a change of the emission
region geometry rather than previously suggested accretion-induced decay of the
neutron stars magnetic field. At lower luminosities, we find for the first time
a hint of departure from the anticorrelation of line energy with flux, which we
interpret as a transition from super- to sub-critical accretion associated with
the disappearance of the accretion column. Finally, we confirm and briefly
discuss the orbital modulation observed in the outburst light curve of the
source.

25
The categories of this paper are: patt-sol
11
The categories of this paper are: hep-lat
18
The categories of this paper are: econ
30
The categories of this paper are: q-alg
3
The categories of this paper are: physics
31
The categories of this paper are: ao-sci
12
The categories of this paper are: nucl-th
33
The categories of this paper are: plasm-ph
14
The categories of this paper are: math-ph
7
The categories of this paper are: hep-th
22
The categories of this paper are: chao-dyn
23
The categories of this paper are: solv-int
26
The categories of this paper are: bayes-an
5
The categories of this paper are: gr-qc
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th