Superorbital modulation of X-ray emission from gamma-ray binary LSI +61 303

Abstract

We report the discovery of a systematic constant time lag between the X-ray and radio flares of the gamma-ray binary LSI +61 303, persistent over long, multi-year, time scale. Using the data of monitoring of the system by RXTE we show that the orbital phase of X-ray flares from the source varies from ${\varphi }_X\simeq 0.35$ to ${\varphi }_X\simeq 0.75$ on the superorbital 4.6 yr time scale. Simultaneous radio observations show that periodic radio flares always lag the X-ray flare by $\Delta {\varphi }_{X-R}\simeq 0.2$. We propose that the constant phase lag corresponds to the time of flight of the high-energy particle filled plasma blobs from inside the binary to the radio emission region at the distance ~10 times the binary separation distance. We put forward a hypothesis that the X-ray bursts correspond to the moments of formation of plasma blobs inside the binary system.

References in corpus (4)

• Discovery of High-Energy Gamma-Ray Emission from the Binary System PSR B1259-63/LS 2883 Around Periastron with Fermi
• VERITAS Observations of the gamma-Ray Binary LS I +61 303
• INTEGRAL and XMM-Newton observations of LSI +61 303
• H-alpha Emission Variability in the gamma-ray Binary LS I +61 303

Cited by in corpus (9)

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• Study of orbital and superorbital variability of LSI +61 303 with X-ray data
• Evidence of coupling between the thermal and nonthermal emission in the gamma-ray binary LS I +61 303
• Modelling the correlated keV/TeV light curves of Be/gamma-ray binaries
• Owens Valley Radio Observatory monitoring of LS I +61°303 completes three cycles of the super-orbital modulation
• A precessing stellar disk model for superorbital modulations of the gamma-ray binary LS I+61${}^{\circ }$ 303
• Achromatic rapid flares in hard X-rays in the $\gamma$-ray binary LS I +61-303