4C52.37 and 3C 293 parsec-scale HI outflows

The clouds are blueshifted by up to ~600km/s with respect to the systemic velocity. 3C 293 is largely resolved out in our VLBI observation, but toward the VLBI core we detect some outflowing HI gas blueshifted with respect to the systemic velocity by up to ~300km/s. We also find indications of outflowing gas toward the other parts of the western lobe suggesting that the HI outflow is extended. Overall, we find that the fraction of HI gas recovered by our VLBI observations varies significantly within our sample, ranging from complete (4C 12.50) to marginal (3C 293).

However, in all cases we find evidence for a clumpy structure of both the outflowing and the quiescent gas, consistent with predictions from numerical simulations. All the outflows include at least a component of relatively compact clouds with masses in the range of 10^4^-10^5^M_{sun}_. The outflowing clouds are often already observed at a few tens of parsecs (in projection) from the core.

We find indications that the HI outflow might have a diffuse component, especially in larger sources. Our results support the interpretation that we observe these AGNs at different stages in the evolution of the interaction between the jet and the interstellar medium and this is reflected in the properties of the outflowing gas as predicted by numerical simulations.