Black hole formation and association to second object.

 Relativity predicts a gravitational connection between a Black Hole and a White Hole. This, theoretically, should happen every time a BH is formed which suggests a causal link in their evolution. That cannot occur in a star before BH formation nor likely to happen after. The relationship forms in the special conditions in a collapse event as the BH is created at a type II supernova.
When a large star dies (large enough for the core to form a BH ) the gravity of the core and the shock wave, from the nova, overcome the strong forces that hold atoms stable. This triggers a violent cascade as the core collapse at enormous speed. That is abruptly stopped by the degeneracy pressure of neutrons at minimum core mass. This creates inertia force that rebounds throwing out a second (assisted by the asymmetric nature of the shock wave around the Core) and associated object which evolves into a WH. Evidence for this separation event comes from gamma ray bursts associated to this type of supernova.
The WH has unusual properties and may fall outside the Main Sequence being BH material without the compactness. Released from gravitational confines this WH evolves. That is accreted directly onto the BH splitting the gravitational connection in two as the accretion disc occupies the equatorial region. That joins the WH gravitationally to the BH’s poles forming a double connection through space and time which uses the rotation of the BH in forming a gravitational vortex (the deviation in gravity between the partners is a deviation in time so the connection is through space and time - or a time bridge).

That WH’s are ejectors will be demonstrated by their slow rotation. They are formed as an ejector not by collapse, as stars and BH are, so rotate slowly. Thus the physical properties of a WH may be; slow rotation, initially low mass, have a double(helix) physical connection to the BH partner and being BH material that has evolved.
This gravitational association may help the BH pull it’s own WH partner in forming a Low Mass X-ray Binary with a causal link in evolution - different from a High Mass Binary that is random.