2014MNRAS.444L..30K

We show that the hyperluminous source HLX-1 may be a stellar-mass binary system like SS433, but seen along its X-ray beams. The precession of these beams gives the ∼ 1 yr characteristic time-scale of the light curve, while the significant X-ray duty cycle means that the precession angle must be comparable with the beam opening angle, which is of the order of 1 _.^○6. The X-ray light curve appears to result from geometric collimation and scattering as the beam moves through the line of sight. Encouragingly, the distance ∼ 95 Mpc suggested for HLX-1 is only a few times larger than the minimum distance at which we can expect to view such a highly beamed system along its axis. This picture allows a simple interpretation of HLX-1 as the most extreme known member of the ultraluminous X-ray source population.