  The formation of planets remains one of the most challenging problems of
contemporary astrophysics. Starting with micron-sized dust grains, coagulation
models predict growth up to centimeter (pebbles), but growth beyond this size
is difficult because of fragmentation and drift. Ways to bypass this problem
have focused on inhomogeneities in the flow, be that zonal flows, streaming
instability, or vortices. Because vortices are in equilibrium between the
Coriolis and the pressure force, the pressureless grains will orbit along a
vortex streamline experiencing a drag force. This is a very effective mechanism
to concentrate pebbles as also seen in numerical simulations and possibly in
ALMA observations. Yet, a high pebble load is dangerous for the vortex, and we
showed that in two-dimensional simulations the backreaction eventually leads to
vortex disruption. We investigate whether the same happens in three dimensions.
We perform 3D simulations with pebbles in a local box finding that, although
the pebbles disturb the vortex around the midplane, the column does not get
destroyed. This result is important because, based on the previous 2D result
suggesting complete disruption, the vortex interpretation of ALMA observations
has been called into question. We show instead that the vortex behaves like a
Taylor column, and the pebbles as obstacles to the flow. Pebble accumulation in
the center of the vortices proceeds to roughly the same concentration as in the
control run without backreaction.
