2FGL J1311.7-3429 Joins the Black Widow Club
Abstract
We have found an optical/X-ray counterpart candidate for the bright, but presently unidentified, Fermi source 2FGL J1311.7-3429. This counterpart undergoes large-amplitude quasi-sinusoidal optical modulation with a 1.56 hr (5626 s) period. The modulated flux is blue at peak, with T eff ≈ 14, 000 K, and redder at minimum. Superimposed on this variation are dramatic optical flares. Archival X-ray data suggest modest binary modulation, but no eclipse. With the γ-ray properties, this appears to be another black-widow-type millisecond pulsar. If confirmation pulses can be found in the GeV data, this binary will have the shortest orbital period of any known spin-powered pulsar. The flares may be magnetic events on the rapidly rotating companion or shocks in the companion-stripping wind. While this may be a radio-quiet millisecond pulsar, we show that such objects are a small subset of the γ-ray pulsar population.
- Publication:
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The Astrophysical Journal
- Pub Date:
- August 2012
- DOI:
- 10.1088/2041-8205/754/2/L25
- arXiv:
- arXiv:1207.1736
- Bibcode:
- 2012ApJ...754L..25R
- Keywords:
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- gamma rays: stars;
- pulsars: general;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- To Appear in the Astrophysical Journal Letters