Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Timing Observations of PSR J1023+0038 During a Low-Mass X-ray Binary
  State   Transitional millisecond pulsars (tMSPs) switch, on roughly multi-year
timescales, between rotation-powered radio millisecond pulsar (RMSP) and
accretion-powered low-mass X-ray binary (LMXB) states. The tMSPs have raised
several questions related to the nature of accretion flow in their LMXB state
and the mechanism that causes the state switch. The discovery of coherent X-ray
pulsations from PSR J1023+0038 (while in the LMXB state) provides us with the
first opportunity to perform timing observations and to compare the neutron
star's spin variation during this state to the measured spin-down in the RMSP
state. Whereas the X-ray pulsations in the LMXB state likely indicate that some
material is accreting onto the neutron star's magnetic polar caps, radio
continuum observations indicate the presence of an outflow. The fraction of the
inflowing material being ejected is not clear, but it may be much larger than
that reaching the neutron star's surface. Timing observations can measure the
total torque on the neutron star. We have phase-connected nine XMM-Newton
observations of PSR J1023+0038 over the last 2.5 years of the LMXB state to
establish a precise measurement of spin evolution. We find that the average
spin-down rate as an LMXB is 26.8+/-0.4% faster than the rate (-2.39x10^-15 Hz
s-1) determined during the RMSP state. This shows that negative angular
momentum contributions (dipolar magnetic braking and outflow) exceed positive
ones (accreted material), and suggests that the pulsar wind continues to
operate at a largely unmodified level. We discuss implications of this tight
observational constraint in the context of possible accretion models.

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The categories of this paper are: hep-th
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The categories of this paper are: gr-qc
33
The categories of this paper are: plasm-ph
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The categories of this paper are: supr-con
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The categories of this paper are: physics
34
The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom
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The categories of this paper are: q-bio
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The categories of this paper are: hep-lat
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The categories of this paper are: eess
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The categories of this paper are: cs
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The categories of this paper are: stat
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The categories of this paper are: nucl-th
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The categories of this paper are: bayes-an
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-fin