Uplift, feedback and buoyancy: radio lobe dynamics in NGC 4472
  We present results from deep (380 ks) \textit{Chandra} observations of the
AGN outburst in the massive early-type galaxy NGC 4472. We detect cavities in
the gas coincident with the radio lobes and estimate the eastern and western
lobe enthalpy to be $(1.1 \pm 0.5 )\times 10^{56}$ erg and $(3 \pm 1 )\times
10^{56}$ erg, and the average power required to inflate the lobes to be $(1.8
\pm 0.9)\times 10^{41}$ erg s$^{-1}$ and $(6 \pm 3)\times 10^{41}$ erg
s$^{-1}$, respectively. We also detect enhanced X-ray rims around the radio
lobes with sharp surface brightness discontinuities between the shells and the
ambient gas. The temperature of the gas in the shells is less than that of the
ambient medium, suggesting that they are not AGN-driven shocks but rather gas
uplifted from the core by the buoyant rise of the radio bubbles. We estimate
the energy required to lift the gas to be up to $(1.1 \pm 0.3 )\times 10^{56}$
erg and $(3 \pm 1 )\times 10^{56}$ erg for the eastern and western rim
respectively, constituting a significant fraction of the total outburst energy.
A more conservative estimate suggests that the gas in the rim was uplifted a
smaller distance, requiring only $20-25\%$ of this energy. In either case, if a
significant fraction of this uplift energy is thermalized via hydrodynamic
instabilities or thermal conduction, our results suggest that it could be an
important source of heating in cool core clusters and groups. We also find
evidence for a central abundance drop in NGC 4472. The iron abundance profile
shows that the region along the cavity system has a lower metallicity than the
surrounding, undisturbed gas, similar to the central region. This also shows
that bubbles have lifted low-metallicity gas from the center.
