Mathematical Principles of Theoretical Physics

454 CHAPTER 7. ASTROPHYSICS AND COSMOLOGY

It is the force (7.4.36) that not only causes the instability of the basic flow (7.4.29), but also
generates jets of the galaxy nucleus.

5.Latitudinal circulation.The above three types of forces: the rotating force (7.4.30), the
thermal expansion force (7.4.32), and the gravitational effect (7.4.35), cause the instability of
the basic flow (7.4.29) and lead to the latitudinal circulation of the galactic nucleus, as shown
in Figure7.9.

Figure 7.9: The latitudinal circulation withk=2 cells.

6.Jets and accretions.Each circulation cell has an exit as shown in Figure7.10, where
the circulating gas is pushed up by the radial force (7.4.35)-(7.4.36), and erupts leading to a
jet. The cell has an entrance as shown in Figure7.10, where the exterior gas is pulled into the
nucleus, is cyclo-accelerated by the force (7.4.35), goes down to the inner boundaryr=Rs,
and then is pushed byFθof (7.4.30) toward to the exit. Thus the circulation cells form jets
in their exits and accretions in their entrances. In Figure7.11(a), we see that there is a jet
in the latitudinal circulation withk=1 cell, and in Figure7.11(b) there are two jets in the
circulation withk=2 cells in its south and north poles, and an accretion disk near its equator.

exit

entrance entrance

Figure 7.10

7.Condition for jet generation.The main power to generate jets comes from the gravi-
tational effect of (7.4.35)-(7.4.36) by the black hole. The radial momentumPrin (7.4.35) is