Fermi Variability Study of the Candidate Pulsar Binary 2FGL~J0523.3-2530

Abstract

The Fermi source 2FGL~J0523.3$-$2530 has recently been identified as a candidate millisecond pulsar binary with an orbital period of 16.5 hrs. We have carried out detailed studies of the source's emission properties by analyzing data taken with the Fermi Large Area Telescope in the 0.2--300 GeV energy range. Long-term, yearly variability from the source has been found, with a factor of 4 flux variations in 1--300 GeV. From spectral analysis, we find an extra spectral component at 2--3 GeV that causes the source brightening. While no orbital modulations have been found from the Fermi data over the whole period of 2008--2014, orbital modulation in the source's $>$2 GeV emission is detected during the last 1.5 yrs of the Fermi observation. Our results support the millisecond pulsar binary nature of 2FGL~J0523.3$-$2530. Multi-wavelength observations of the source are warranted in order to find any correlated flux variations and thus help determine the origin of the long-term variability, which currently is not understood.

arXiv comment8 pages, 5 figures, comments from Referee were incorporated, accepted for publication in ApJ

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Cited by in corpus (4)

• Classification and Ranking of Fermi LAT Gamma-ray Sources from the 3FGL Catalog using Machine Learning Techniques
• Fermi Observation of the transitional pulsar binary XSS J12270-4859
• Discovery of Gamma-Ray Orbital Modulation in the Black Widow PSR J1311-3430
• Luminous Optical and X-ray Flaring of the Putative Redback Millisecond Pulsar 1FGL J0523.5$-$2529