Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: GBT Discovery of Two Binary Millisecond Pulsars in the Globular Cluster
  M30   We report the discovery of two binary millisecond pulsars in the
core-collapsed globular cluster M30 using the Green Bank Telescope (GBT) at 20
cm. PSR J2140-2310A (M30A) is an eclipsing 11-ms pulsar in a 4-hr circular
orbit and PSR J2140-23B (M30B) is a 13-ms pulsar in an as yet undetermined but
most likely highly eccentric (e>0.5) and relativistic orbit. Timing
observations of M30A with a 20-month baseline have provided precise
determinations of the pulsar's position (within 4" of the optical centroid of
the cluster), and spin and orbital parameters, which constrain the mass of the
companion star to be m_2 >~ 0.1Msun. The position of M30A is coincident with a
possible thermal X-ray point source found in archival Chandra data which is
most likely due to emission from hot polar caps on the neutron star. In
addition, there is a faint (V_555 ~ 23.8) star visible in archival HST F555W
data that may be the companion to the pulsar. Eclipses of the pulsed radio
emission from M30A by the ionized wind from the compact companion star show a
frequency dependent duration (\propto\nu^{-\alpha} with \alpha ~ 0.4-0.5) and
delay the pulse arrival times near eclipse ingress and egress by up to 2-3 ms.
Future observations of M30 may allow both the measurement of post-Keplerian
orbital parameters from M30B and the detection of new pulsars due to the
effects of strong diffractive scintillation.

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The categories of this paper are: econ
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The categories of this paper are: alg-geom
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The categories of this paper are: cond-mat
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The categories of this paper are: hep-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: supr-con
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The categories of this paper are: plasm-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: mtrl-th
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The categories of this paper are: ao-sci
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The categories of this paper are: solv-int
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The categories of this paper are: cmp-lg
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The categories of this paper are: patt-sol
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The categories of this paper are: adap-org
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The categories of this paper are: stat