Title: Gap and rings carved by vortices in protoplanetary dust,
Abstract: Large-scale vortices in protoplanetary disks are thought to form and survive
for long periods of time. Hence, they can significantly change the global disk
evolution and particularly the distribution of the solid particles embedded in
the gas, possibly explaining asymmetries and dust concentrations recently
observed at sub-millimeter and millimeter wavelengths. We investigate the
spatial distribution of dust grains using a simple model of protoplanetary disk
hosted by a giant gaseous vortex. We explore the dependence of the results on
grain size and deduce possible consequences and predictions for observations of
the dust thermal emission at sub-millimeter and millimeter wavelengths. Global
2D simulations with a bi-fluid code are used to follow the evolution of a
single population of solid particles aerodynamically coupled to the gas.
Possible observational signatures of the dust thermal emission are obtained
using simulators of ALMA and ngVLA observations. We find that a giant vortex
not only captures dust grains with Stokes number St < 1 but can also affect the
distribution of larger grains (with St '~' 1) carving a gap associated to a
ring composed of incompletely trapped particles. The results are presented for
different particle size and associated to their possible signatures in disk
observations. Gap clearing in the dust spatial distribution could be due to the
interaction with a giant gaseous vortex and their associated spiral waves,
without the gravitational assistance of a planet. Hence, strong dust
concentrations at short sub-mm wavelengths associated with a gap and an
irregular ring at longer mm and cm wavelengths could indicate the presence of
an unseen gaseous vortex.