Revealing a new black widow binary 4FGL J0336.0+7502

Kwan Lok Li, Y. X.Jane Yap, Chung Yue Hui, Albert K.H. Kong

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


We report on the discovery of a promising candidate for a black widow (BW) millisecond pulsar binary, 4FGL J0336.0+7502, which shows many pulsar-like properties in the 4FGL-DR2 catalog. Within the 95% error region of the LAT source, we identified an optical counterpart with a clear periodicity at Porb = 3.718178(9) hr using the Bohyunsan 1.8 m Telescope, the Lulin One-meter Telescope, the Canada–France–Hawaii Telescope, and Gemini-North. At the optical position, an X-ray source was marginally detected in the Swift/X-Ray Telescope archival data, and the detection was confirmed by our Chandra/ACIS DDT observation. The spectrum of the X-ray source can be described by a power-law model of Γx = 1.6 ± 0.7 and F0.3–7 keV = 3.5-+1.01.2 ´ 10-14 erg cm−2 s−1. The X-ray photon index and the low X-ray-to-γ-ray flux ratio (i.e., <1%) are both consistent with that of many known BW pulsars. There is also a hint of an X-ray orbital modulation in the Chandra data, although the significance is very low (1.3σ). If the pulsar identity and the X-ray modulation are confirmed, it would be the fifth BW millisecond pulsar binary that showed an orbitally modulated emission in X-rays.

Original languageEnglish
Article number92
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 2021 Apr 20

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'Revealing a new black widow binary 4FGL J0336.0+7502'. Together they form a unique fingerprint.

Cite this