Gamma-rays from SS433: evidence for periodicity

Abstract: In this paper we present our study of the gamma-ray emission from the microquasar SS433. Integrating over 9 years of Fermi-LAT \textsc{pass8} data, we detect SS433 with a significance of ~13$\sigma$ in the 200 to 500 MeV photon energy range, with evidence for an extension in the direction of the w1 X-ray hotspot. A temporal analysis reveals evidence for modulation of SS433's gamma-ray emission with the precession period of its relativistic jet. This suggests that at least some of SS433's gamma-ray emission originates close to the object rather than from the jet termination regions.