The lengths of the jets are determined by the peak of the repulsive dipole gravity potential on both poles of the rotation axis. The strength of dipole gravity falls more rapidly than the Newtonian gravity, so at certain point of the distance from the center, the attractive force of Newtonian gravity will dominate over the repulsive force of dipole gravity, which is the cause of the return trajectory and the brightly lit jets observed from the black hole accretion disks.
Essentially, the property of the linear trajectory is a function of the rotational frequency, total mass and the geometrical shape of the galactic core which determine the magnitude of the length element of the relativistic center of mass shift. Since the geometrical shape of the core can not be determined apriori, and also since its observation is out of the reach of the currently known method, the gravitational dipole moment will need to be treated as an adjustable parameter. One can assume a certain shape for the core, its mass(density as well) and the rotational frequency to estimate the actual length of the jets. It is noted that the length of the jets are very sensitive to the peak height of the repulsive dipole gravity potential. Due to the thermal fluctuation of the molten core material before the ejection, it is expected that there will be corresponding fluctuations on the length on the jets and also on the population density of the dark matter halo. The estimated dark matter population density function predicted by dipole gravity is 1/r. However, this density function suggests an infinite wise distribution which can not be true. So at certain point at the far out distance, the density distribution function is expected to decrease more rapidly than 1/r, because the density distribution can not suddenly be truncated to zero at distance r=ro(ro is the distance where the density distribution deviates from 1/r). In this sense, NFW's proposal of 1/r^3 dependency on the density distribution beyond certain distance limit r=ro is justified. (I'm indebted to Prof. Joel Primack for providing me with this information).
It would be interesting to see if the property of the thermal distribution of the molten core material could be related to the 1/r^3 dependency in the population density of the dark matter halo at the far out stretch as the compressed molten material would not all have the same kinetic energy at the peak height of the repulsive dipole gravity potential.
Theory of Gravitation, Cosmology and a part of general relativity