Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Peculiar Spin Frequency and Radio Profile Evolution of PSR J1119$-$6127
  Following Magnetar-like X-ray Bursts   We present the spin frequency and profile evolution of the radio pulsar
J1119$-$6127 following magnetar-like X-ray bursts from the system in 2016 July.
Using data from the Parkes radio telescope, we observe a smooth and fast
spin-down process subsequent to the X-ray bursts resulting in a net change in
the pulsar rotational frequency of $\Delta\nu\approx-4\times10^{-4}$\,Hz.
During the transition, a net spin-down rate increase of
$\Delta\dot\nu\approx-1\times10^{-10}$\,Hz\,s$^{-1}$ is observed, followed by a
return of $\dot{\nu}$ to its original value. In addition, the radio pulsations
disappeared after the X-ray bursts and reappeared about two weeks later with
the flux density at 1.4\,GHz increased by a factor of five. The flux density
then decreased and undershot the normal flux density followed by a slow
recovery back to normal. The pulsar's integrated profile underwent dramatic and
short-term changes in total intensity, polarization and position angle. Despite
the complex evolution, we observe correlations between the spin-down rate,
pulse profile shape and radio flux density. Strong single pulses have been
detected after the X-ray bursts with their energy distributions evolving with
time. The peculiar but smooth spin frequency evolution of PSR~J1119$-$6127
accompanied by systematic pulse profile and flux density changes are most
likely to be a result of either reconfiguration of the surface magnetic fields
or particle winds triggered by the X-ray bursts. The recovery of spin-down rate
and pulse profile to normal provides us the best case to study the connection
between high magnetic-field pulsars and magnetars.

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The categories of this paper are: chao-dyn
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The categories of this paper are: plasm-ph
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The categories of this paper are: nlin
14
The categories of this paper are: math-ph
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The categories of this paper are: supr-con
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The categories of this paper are: q-fin
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The categories of this paper are: nucl-th
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The categories of this paper are: math
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-lat
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The categories of this paper are: chem-ph
35
The categories of this paper are: mtrl-th
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The categories of this paper are: hep-ph
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The categories of this paper are: stat
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The categories of this paper are: acc-phys
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The categories of this paper are: ao-sci