  Spitzer spectral maps reveal a disk of highly luminous, warm (>150 K) H2 in
the center of the massive spiral galaxy Messier 58, which hosts a radio-loud
AGN. The inner 2.6 kpc of the galaxy appears to be overrun by shocks from the
radio jet cocoon. Gemini NIRI imaging of the H2 1-0 S(1) emission line, ALMA CO
2-1, and HST multiband imagery indicate that much of the molecular gas is
shocked in-situ, corresponding to lanes of dusty molecular gas that spiral
towards the galaxy nucleus. The CO 2-1 and ionized gas kinematics are highly
disturbed, with velocity dispersion up to 300 km/s. Dissipation of the
associated kinetic energy and turbulence, likely injected into the ISM by
radio-jet driven outflows, may power the observed molecular and ionized gas
emission from the inner disk. The PAH fraction and composition in the inner
disk appear to be normal, in spite of the jet and AGN activity. The PAH ratios
are consistent with excitation by the interstellar radiation field from old
stars in the bulge, with no contribution from star formation. The phenomenon of
jet-shocked H2 may substantially reduce star formation and help to regulate the
stellar mass of the inner disk and supermassive black hole in this otherwise
normal spiral galaxy. Similarly strong H2 emission is found at the centers of
several nearby spiral and lenticular galaxies with massive bulges and
radio-loud AGN.
