The young radio lobe of 3C 84: inferred gas properties in the central 10
  parsec
  We analyse the environment of the supermassive black hole (SMBH) in the
centre of a massive elliptical galaxy NGC 1275 in the Perseus cluster, hosting
the radio source 3C 84. We focus on the young radio lobe observed inside the
estimated Bondi accretion radius. We discuss the momentum balance between the
jet associated with the lobe and the surrounding gas. The results are compared
with the proper motion of the radio lobe obtained with the very long baseline
interferometry. We find that under assumption of a high-density environment >~
100 cm^-3), the jet power must be comparable to the Eddington luminosity ---
this is clearly inconsistent with the current moderate activity of 3C 84, which
indicates instead that the jet is expanding in a very low density region (<~1
cm^-3), along the rotation axis of the accretion flow. The power required for
the jet to expand in the low-density environment is comparable to the past
average jet power estimated from the X-ray observations. We estimate the
classical Bondi accretion rate, assuming that (1) gas accretion is spherically
symmetric, (2) accretion is associated with the jet environment, and (3) the
medium surrounding the jet is representative of the properties of the dominant
accreting gas. We find that Bondi accretion is inconsistent with the estimated
jet power. This means that either accretion of the cold gas in the NGC 1275 is
more efficient than that of the hot gas, or the jets are powered by the SMBH
spin.
