In the optical spectra of galaxies, methods for the separation of lineemission arising from star formation and an additional hard component, such asshocks or AGN, is well-understood and possible with current diagnostics.However, such diagnostics fail when attempting to separate and define lineemission which arises from shocked gas, and that arising from AGN. We present anew three-dimensional diagnostic diagram for IFU data which can simultaneouslyseparate the line emission amongst star formation, shocks, and AGN within agalaxy. We show that regions we define as AGN-dominated correlate well with thehard X-ray distribution in our test case NGC 1068, as well as with knownregions of AGN activity in NGC 1068. Similarly, spaxels defined asshock-dominated correlate strongly with regions of high velocity dispersionwithin the galaxy.

The inner disc of the local group galaxy M33 appears to be in settledrotational balance, and near IR images reveal a mild, large-scale, two-armspiral pattern with no strong bar. We have constructed N-body models that matchall the extensive observational data on the kinematics and surface density ofstars and gas in the inner part of M33. We find that currently favoured modelsare unstable to the formation of a strong bar of semi-major axis 2 < a_B < 3kpc on a time-scale of 1 Gyr, which changes the dynamical properties of themodels to become inconsistent with the current, apparently well-settled, state.The formation of a bar is unaffected by how the gas component is modelled, byincreasing the mass of the nuclear star cluster, or by making the dark matterhalo counter-rotate, but it can be prevented by either reducing themass-to-light ratio of the stars to Upsilon_V ~ 0.6 or Upsilon_K ~ 0.23 insolar units or by increasing the random motions of the stars. Also a shorterand weaker bar results when the halo is rigid and unresponsive. However, allthree near-stable models support multi-arm spirals, and not the observedlarge-scale bi-symmetric spiral. Thus the survival of the current state of thisexceptionally well-studied galaxy is not yet understood.

One of the greatest challenges to theoretical models of massive galaxyformation is the regulation of star formation at early times. The relativeroles of molecular gas expulsion, depletion, and stabilization are uncertain asdirect observational constraints of the gas reservoirs in quenched or quenchinggalaxies at high redshift are scant. We present ALMA observations of CO(2-1) ina massive ($\log M_{\star}/M_{\odot}=11.2$), recently quenched galaxy at$z=1.522$. The optical spectrum of this object shows strong Balmer absorptionlines, which implies that star formation ceased $\sim$0.8 Gyr ago. We do notdetect CO(2-1) line emission, placing an upper limit on the molecular$\mathrm{H_2}$ gas mass of 1.1$\times10^{10}\,M_{\odot}$. The implied gasfraction is $f_{\rm{H_2}}{\equiv M_{H_2}/M_{\star}}<7\%$, $\sim10\times$ lowerthan typical star forming galaxies at similar stellar masses at this redshift,among the lowest gas fractions at this specific star formation rate at anyepoch, and the most stringent constraint on the gas contents of a $z>1$ passivegalaxy to date. Our observations show that the depletion of $\mathrm{H_2}$ fromthe interstellar medium of quenched objects can be both efficient and fairlycomplete, in contrast to recent claims of significant cold gas in recentlyquenched galaxies. We explore the variation in observed gas fractions inhigh-$z$ galaxies and show that galaxies with high stellar surface density havelow $f_{\rm{H_2}}$, similar to recent correlations between specific starformation rate and stellar surface density.