Mass flows and their behaviors in the SS433--W50 system

Abstract

We propose the scenario to interpret the overall observational features of the SS433--W50 system. The most unique features of SS433 are the presence of the precessing, mildly relativistic jets and the obscuration of the central engine, which are considered to be due to a supercritical accretion on to the central compact object. The jets are likely to be ejected from the innermost region of the accretion flow. The concept of the accretion ring (Inoue 2021, PASJ, 73,795) is applied to the outer boundary of the accretion flow and the ring is supposed to have a precession. The accretion ring is expected to extend a two-layer outflow of a thin excretion disk and a thick excretion flow, as well as the accretion flow. The thin excretion disk is discussed to eventually form the optically thick excretion belt along the Roche lobe around the compact object, contributing to the obscuration of the central engine. The thick excretion flow is likely to turn to the supersonic wind (disk wind) with the terminal velocity of $\sim 10^{8}$ cm s$^{-1}$ and to collide with the SNR matter at the distance of $\sim 10^{18}$ cm. The interactions of the jets with the disk wind are considered to cause the features of the jets observed at the distances of 10$^{14} \sim 10^{15}$ cm and $\sim 10^{17}$ cm. Finally, it is discussed that the jets are braked by the SNR matter at the distance of $\sim$10 pc and the momentum carried by the jet is transferred to the SNR matter shoved by the jet. The SNR matter pushed to the inside of the precession cone is expected to gather along the cone axis and to form the elongated structures in the east and west directions from the main W50 structure.