PSR J1723-2837: An eclipsing binary radio millisecond pulsar

Fronefield Crawford, Andrew G. Lyne, Ingrid H. Stairs, David L Kaplan, Maura A. McLaughlin, Paulo C C Freire, Marta Burgay, Fernando Camilo, Nichi D'Amico, Andrew Faulkner, Michael Kramer, Duncan R. Lorimer, Richard Norman Manchester, Andrea Possenti, Danny Steeghs

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Abstract

We present a study of PSR J1723-2837, an eclipsing, 1.86 ms millisecond binary radio pulsar discovered in the Parkes Multibeam survey. Radio timing indicates that the pulsar has a circular orbit with a 15 hr orbital period, a low-mass companion, and a measurable orbital period derivative. The eclipse fraction of ∼15% during the pulsar's orbit is twice the Roche lobe size inferred for the companion. The timing behavior is significantly affected by unmodeled systematics of astrophysical origin, and higher-order orbital period derivatives are needed in the timing solution to account for these variations. We have identified the pulsar's (non-degenerate) companion using archival ultraviolet, optical, and infrared survey data and new optical photometry. Doppler shifts from optical spectroscopy confirm the star's association with the pulsar and indicate a pulsar-to-companion mass ratio of 3.3 ± 0.5, corresponding to a companion mass range of 0.4 to 0.7 MȮ and an orbital inclination angle range of between 30° and 41°, assuming a pulsar mass range of 1.4-2.0 MȮ. Spectroscopy indicates a spectral type of G for the companion and an inferred Roche-lobe-filling distance that is consistent with the distance estimated from radio dispersion. The features of PSR J1723-2837 indicate that it is likely a "redback" system. Unlike the five other Galactic redbacks discovered to date, PSR J1723-2837 has not been detected as a γ-ray source with Fermi. This may be due to an intrinsic spin-down luminosity that is much smaller than the measured value if the unmeasured contribution from proper motion is large.

Original languageEnglish
Article number20
JournalThe Astrophysical Journal
Volume776
Issue number1
DOIs
Publication statusPublished - 10 Oct 2013
Externally publishedYes

Keywords

  • binaries: eclipsing
  • pulsars: individual (PSR J1723-2837)

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