1FGL J0523.5-2529: A new probable gamma-ray pulsar binary

Jay Strader, Laura Chomiuk, Eda Sonbas, Kirill Sokolovsky, David J. Sand, Alexander S. Moskvitin, C. C. Cheung

Research output: Contribution to journalArticlepeer-review

37 Scopus citations


We report optical photometric and Southern Astrophysical Research spectroscopic observations of an X-ray source found within the localization error of the Fermi Large Area Telescope unidentified γ-ray source 1FGL J0523.5-2529. The optical data show periodic flux modulation and radial velocity variations indicative of a binary with a 16.5 hr period. The data suggest a massive non-degenerate secondary (≳ 0.8 M ), and we argue the source is likely a pulsar binary. The radial velocities have good phase coverage and show evidence for a measurable eccentricity (e = 0.04). There is no clear sign of irradiation of the secondary in either photometry or spectroscopy. The spatial location out of the Galactic plane and γ-ray luminosity of the source are more consistent with classification as a recycled millisecond pulsar than as a young pulsar. Future radio timing observations can confirm the identity of the primary and further characterize this interesting system.

Original languageEnglish (US)
Article numberL27
JournalAstrophysical Journal Letters
Issue number2
StatePublished - Jun 20 2014
Externally publishedYes


  • X-rays: general
  • binaries: spectroscopic
  • gamma rays: general
  • pulsars: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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