A Multi-Wavelength Study of the Gamma Ray Binary 1FGL J1018.6-5856

We report on a multi-wavelength study of 1FGL J1018.6-5856, the first Gamma-ray Binary discovered by the Fermi Large Area Telescope (LAT). 1FGL J1018.6-5856 consists of a O6 V((f)) star and suspected rapidly spinning pulsar, which is possibly powered by the interaction between the relativistic pulsar wind and the stellar wind of the companion. A microquasar scenario where the compact object is a black hole cannot be ruled out. We investigate long-term changes in the gamma-ray properties of the orbital modulation. Using probability weighted photometry, long-term observations with the LAT give a refined value of the orbital period at 16.549±0.007 days. Folding the gamma-ray light curves reveal a quasi-sinusoidal component as well as the presence of flare-like behavior. We also search for phase-resolved changes in the gamma ray spectral properties of 1FGL J1018.6-5856. We compare the long term variability in gamma-rays with those in the X-ray and radio bands from Swift X-ray Telescope and Australia Telescope Compact Array.