This is a fairly technical paper, so it may be useful to provide a little more context as to what the authors are doing. There are currently a number of open questions in the field of galaxy formation, and there have been for quite some time. Most of these questions center around a number of strange observations.

One open question is the origin of the M-sigma relation. This is a fairly strong correlation that is observed between the masses of galaxies and the masses of the supermassive black holes (SMBHs) that reside at their centers. It is not known why a small object at the very center of a galaxy would seem grow in lockstep with the global structure of the galaxy, many thousands of light-years away.

Another open question is why massive galaxies have the masses that they do. There is a joke in the galaxy formation community that there are only two problems with galaxy mass predictions: predicting the mass of high-mass galaxies, and predicting the mass of low-mass galaxies. Under standard models, massive galaxies are predicted to be much more massive than currently observed. Somehow, the surrounding gas in the intergalactic medium does not get accreted onto these galaxies.

These observations have motivated the theory of "AGN feedback." The idea here is that the SMBH at the center of a galaxy accretes gas from the surrounding interstellar medium (ISM). As this gas falls onto the SMBH, it (somehow) forms a jet, which then interacts with the ISM of the rest of the galaxy. We often see these jets in radio wavelengths, where they're called FR I and FR II sources. (I found a few new ones myself in my very first paper [1].) These AGN-powered jets then (somehow) interact with the ISM in such a way as to regulate the growth of the galaxy. They perhaps quench the flow of gas from the intergalactic medium onto the galaxy. This then (hopefully) causes the galaxy to not get too big, and the SMBH to grow in step with the growth of the galaxy.

But there's are a lot of hand waving that goes with AGN feedback as its currently understood. Firstly, it's not clear how the SMBH actually forms a jet in the first place and what the jet is made of. (There are good theories like the Blandford-Znajek mechanism, but I don't think they've been definitively proven.) And it's not well understood how the jet itself actually interacts with the ISM. It can heat up the ISM in a bubble somewhere, but it's not obvious how that quenches inflows onto the galaxy in other places. Furthermore, it's thought, but not definitively known, that these jets can promote star formation.

The galaxy studied in this paper, IC 5063, seems to be a good candidate to study because the jet happens to pass nearly through the plane of the galaxy, so the interaction between the jet and the ISM is fairly large. With the ALMA telescope now starting to collect science data, it's possible to observe this interaction at much higher resolution than was before possible.

Based on my reading of this paper, the main result seems to be that the jet-driven wind is partially optically thin rather than optically thick. This means that earlier estimates of the molecular mass of the jet-driven winds were too high, by about an order of magnitude. But this seems to be a preliminary result, and the authors will do a more thorough calculation when the rest of the ALMA data comes in.

[1]: http://adsabs.harvard.edu/abs/2012ApJ...756..116A