Three-dimensional mapping of the local interstellar medium with
  composite data
  Three-dimensional maps of the Galactic interstellar medium are general
astrophysical tools. Reddening maps may be based on the inversion of color
excess measurements for individual target stars or on statistical methods using
stellar surveys. Three-dimensional maps based on diffuse interstellar bands
(DIBs) have also been produced. All methods benefit from the advent of massive
surveys and from Gaia data. We first updated our previous local dust maps based
on a regularized Bayesian inversion of individual color excess data by
replacing Hipparcos or photometric distances with Gaia Data Release 1 values
when available. Secondly, we complemented this database with a series of ~5,000
color excess values estimated from the strength of the lambda 15273 DIB toward
stars from SDSS/APOGEE, possessing a Gaia parallax. Third, we computed a
low-resolution map based on a grid of Pan-STARRS reddening measurements by
means of a new hierarchical technique and used this map as the prior
distribution during the inversion of the two other datasets. Here we present a
first attempt to combine different datasets and methods to improve the local
maps. The use of Gaia parallaxes introduces significant changes in some areas
and globally increases the compactness of the structures. Additional DIB-based
data make it possible to assign distances to clouds located behind closer
opaque structures and do not introduce contradictory information for the close
structures. A more realistic prior distribution instead of a plane-parallel
homogeneous distribution helps better define the structures. We validated the
results through comparisons with other maps and with soft X-ray data. Our study
demonstrates that the combination of various tracers is a potential tool for
more accurate maps. An online tool makes it possible to retrieve maps and
reddening estimations (http://stilism.obspm.fr).
