Connection between orbital modulation of Hα and gamma-rays in the Be/X-ray binary LS I+61°303

• Published in: Astronomy and astrophysics (Berlin) 2014-01, Vol.561, p.L2
• Main Authors: Zamanov, R., Martí, J., Stoyanov, K., Borissova, A., Tomov, N. A.
• Format: Article
• Language: English
• Subjects: gamma rays: stars; outflows; stars: emission-line; stars: individual: LS I+61°303; stars: winds; X-rays: binaries
• ISSN: 0004-6361; 1432-0746
• DOI: 10.1051/0004-6361/201322936

We studied the average orbital modulation of various parameters (γ-ray flux, Hα emission line, optical V band brightness) of the radio- and γ-ray emitting Be/X-ray binary LS I + 61°303. Using the Spearman rank correlation test, we found highly significant correlations between the orbital variability of the equivalent width of the blue hump of the Hα and Fermi-LAT flux with a Spearman p-value  ~2 × 10-5, and the equivalent widths ratio EWB/EWR and Fermi-LAT flux with p-value  ~9 × 10-5. We also found a significant anti-correlation between Fermi-LAT flux and V band magnitude with a p-value  ~7 × 10-4. All these correlations refer to the average orbital variability, and we conclude that the Hα and γ-ray emission processes in LS I + 61°303 are connected. The possible physical scenario is briefly discussed.