The nature of SS433 and the ultraluminous X-ray sources

The periodic precession (162–day) and nodding (6.3–day) motions of the jets in SS433 are driven in the outer regions of the disc, whereas the jets themselves, being relativistic, are launched near the black hole at the disc centre. Given that the nutation period is comparable to the dynamical timescale in the outer regions of the disc, it seems unlikely that these periods can be communicated efficiently to the disc centre. Here we propose that the massive outflow observed in SS433 is launched at large radii in the disc, about 1/10 of the outer disc edge, and that it is this outflow which responds to the oscillations of the outer disc and determines the direction of the jets. The massive outflow is launched at large radius because the mass transfer rate is hyper-Eddington. This implies not only that the total luminosity of SS433 exceeds LEdd by a considerable factor, but also that the radiative output is collimated along the outflow. We thus suggest that SS433 is an ultraluminous X–ray source (ULX) viewed ‘from the side’. We also suggest that the obscured INTEGRAL sources may be SS433–like objects, but with slightly lower mass transfer rates