nice result.

Appears that low mass black hole X ray binaries are likely the result of the collapse of a single progenitor star.

The core of the relatively massive supergiant becomes a black hole develops gamma ray emitting jets. the accretion disc immediately surrounding the core drops the bulk of the inner star onto the black hole feeding gamma ray bursts from both poles; and the outer layers of the star collapse into a magnetically constrained drag & spin disc with the inner edge (hot) feeding the accretion disc.

The bulk of the drag & spin disc is subject to gravitational moderation and is able to condense into a gravitationally bound object which is usually star sized. Its inner edge is constrained by the transition from magnetically constrained "drag & spin",(the drag & spin disc)... to the accretion disc where the gravity of the black hole induces tidal forces preventing condensation of a discrete mass, and collision of particles heats and forces particles out of a stable circular orbit,(the bulk drops into the black hole hence accretion).
With a "drag & spin disc" the outer edge is constrained by the radius of magnetic influence of the black hole. For a billion solar mass black hole the diameter is about 60,000 light years. Stellar mass black holes are much less massive, and the drag & spin radius of the dynamo magnetic field is reduced according to the mass. It is plenty big enough to fit a newly condensed (from the outer layers of the collaped supergiant) companion star in.

So having got a black hole with very close companion in extremely rapid orbit, the next fun bit is generating the gamma and x ray nova flares. This is relatively easy, as the rapid orbit produces a tightly constrained rotation rate to the companion visible star with the result that it undergoes RS type variability with large starspots, flares and coronal mass ejections etc.
The starspots produced by the tangled magnetic field of the normal RS variable star get in the way of its radiative granules with the result that the star has to expand to fit the granules into the photosphere. The result is that during starspot maxima, the star expands beyond the roche limit and drops gas from the point of the ellipsoid onto the accretion disc causing a radiation flare as it drops into the black hole.

As it sits in the drag & spin disc, the orbit of the companion star around the black hole will be stable unless it is being tidally bumped inward by the influence of a 3rd object in the system. In the case of tidal forcing, the companion star will decrease in mass with periodic X ray nova flares until it decreases to planet size and below. Simultaneously in a 3 body in the disc system the outer companion will drift away by tidal forcing from the merging pair.

There are now a number of low mass companion black hole X ray novae. The black hole in this case is likely close to the lower limit of the mass of a stellar mass black hole. If it is a periodic X ray nova with relatively massive stellar mass black hole, there may be a 3rd body in the system.

In the case or normal low mass companion black hole X ray novae the nova flares will continue until the star has pumped its outer layers through the inner point of the roche lobe onto the black hole, resulting in future RS variations being stable and the only mass transfer being then coronal mass ejections and stellar wind input onto the accretion disc in a steady state.
In a 2 body system, RS variability driven X ray novae will be a feature only of relatively young post supernova systems.

Have a nice day: Ag