Updated Gaia-2MASS 3D maps of Galactic interstellar dust
  Three-dimensional (3D) maps of Galactic interstellar dust are a tool for a
wide range of uses. We aim to construct 3D maps of dust extinction in the Local
Arm and surrounding regions. Gaia EDR3 photometric data were combined with
2MASS measurements to derive extinction towards stars with accurate photometry
and relative uncertainties on parallaxes of less than 20%. We applied our
hierarchical inversion algorithm adapted to inhomogeneous spatial distributions
of target stars to this catalogue of extinctions. We present the updated 3D
dust extinction distribution and provide an estimate of the error on integrated
extinctions from the Sun to each area in the 3D map. The computational area is
similar to the one of the previous DR2 map, a 6 kpc x 6 kpc x 0.8
kpcAstrophysics volume around the Sun. Due to the addition of fainter target
stars, the volume in which the clouds can be reconstructed has increased. Due
to the improved accuracy of the parallaxes and photometric data in EDR3,
extinctions among neighbouring targets are more consistent, allowing one to
reach an increased contrast in the dense areas, while cavity contours are more
regular. We show several comparisons with recent results on dust and star
distributions. The wavy pattern around the Plane of the dust concentrations is
better seen and exists over large regions. Its mean vertical peak-to-peak
amplitude is of the order of 300 pc; interestingly, it is similar to the
vertical period of the spectacular snail-shaped stellar kinematical pattern
discovered in Gaia data. The Gaia EDR3 catalogue allows for a significant
improvement of the extinction maps to be made and the hierarchical technique
confirms its efficiency for massive datasets. Future comparisons between 3D
maps of interstellar matter and stellar distributions may help to understand
which mergers or internal perturbations have shaped the Galaxy within the first
3 kpc.
