Impact parameter for companion disk

If we modify simple BH accretion about a fixed object by applying an acceleration that is perpendicular to the direction of the flow - then it is reasonable to expect the 'backflow' to be aimed towards a position somewhere in between the object's original position and current position because the material that is captured has been accelerated on average towards a retarted position. If we take the time scale for this capture as RBondi/vwind we can calculate a distance the object will have moved due to acceleration as . If the acceleration is not perpendicular to the flow but at some angle then it is the projection of the acceleration perpendicular to the flow that matters…

If we now imagine that we are in an intertial frame of reference that is comoving with the secondary's velocity at t0 - we have the secondary accelerating towards the primary at and the projection relative to the incoming flow velocity as just . Given that acceleration of captured material occurs over a time scale we get that the offset should go as and should be radially outwards. This would imply that the backflow would return outside of the secondary and would then proceed into a prograde orbit about the secondary.

Comments

1. martinhe -- 13 years ago

Once a small disk forms, the impact parameter should also scale up with the disk's radius; where the specific angular momentum of material located on the orbital plane, moving towards the secondary, equals it's Keplerian value.