On the Milky Way spiral arms from open clusters in Gaia EDR3
  Context. The physical processes driving the formation of Galactic spiral arms
are still under debate. Studies using open clusters favour the description of
the Milky Way spiral arms as long-lived structures following the classical
density wave theory. Current studies comparing the Gaia DR2 field stars
kinematic information of the Solar neighbourhood to simulations, find a better
agreement with short-lived arms with a transient behaviour. Aims. Our aim is to
provide an observational, data-driven view of the Milky Way spiral structure
and its dynamics using open clusters as the main tracers, and to contrast it
with simulation-based approaches. We use the most complete catalogue of Milky
Way open clusters, with astrometric Gaia EDR3 updated parameters, estimated
astrophysical information and radial velocities, to re-visit the nature of the
spiral pattern of the Galaxy. Methods. We use a Gaussian mixture model to
detect overdensities of open clusters younger than 30 Myr that correspond to
the Perseus, Local, Sagittarius and Scutum spiral arms, respectively. We use
the birthplaces of the open cluster population younger than 80 Myr to trace the
evolution of the different spiral arms and compute their pattern speed. We
analyse the age distribution of the open clusters across the spiral arms to
explore the differences in the rotational velocity of stars and spiral arms.
Results. We are able to increase the range in Galactic azimuth where
present-day spiral arms are described, better estimating its parameters by
adding 264 young open clusters to the 84 high-mass star-forming regions used so
far, thus increasing by a 314% the number of tracers. We use the evolution of
the open clusters from their birth positions to find that spiral arms nearly
co-rotate with field stars at any given radius, discarding a common spiral
pattern speed for the spiral arms explored. [abridged]
