Isothermal Bondi accretion in two-component Jaffe galaxies with a
  central black hole
  The fully analytical solution for isothermal Bondi accretion on a black hole
(MBH) at the center of two-component Jaffe (1983) galaxy models is presented.
In a previous work we provided the analytical expressions for the critical
accretion parameter and the radial profile of the Mach number in the case of
accretion on a MBH at the center of a spherically symmetric one-component Jaffe
galaxy model. Here we apply this solution to galaxy models where both the
stellar and total mass density distributions are described by the Jaffe
profile, with different scale-lengths and masses, and to which a central MBH is
added. For such galaxy models all the relevant stellar dynamical properties can
also be derived analytically (Ciotti & Ziaee Lorzad 2018). In these new models
the hydrodynamical and stellar dynamical properties are linked by imposing that
the gas temperature is proportional to the virial temperature of the galaxy
stellar component. The formulae that are provided allow to evaluate all flow
properties, and are then useful for estimates of the scale-radius and the mass
flow rate when modeling accretion on massive black holes at the center of
galaxies. As an application, we quantify the departure from the true mass
accretion rate of estimates obtained using the gas properties at various
distances from the MBH, under the hypothesis of classical Bondi accretion.
