2019MNRAS.483.4277C

We present new three-dimensional (3D) interstellar dust reddening maps of the Galactic plane in three colours, E(G - K_S), E(G_BP - G_RP), and E(H - K_S). The maps have a spatial angular resolution of 6 arcmin and covers over 7000 deg² of the Galactic plane for Galactic longitude 0° < l < 360° and latitude |b| < 10°. The maps are constructed from robust parallax estimates from the Gaia Data Release 2 (Gaia DR2) combined with the high-quality optical photometry from the Gaia DR2 and the infrared photometry from the Two Micron All Sky Survey and Wide-Field Infrared Survey Explorer survey. We estimate the colour excesses, E(G - K_S), E(G_BP - G_RP), and E(H - K_S), of over 56 million stars with the machine-learning algorithm Random Forest regression, using a training data set constructed from the large-scale spectroscopic surveys, Large Sky Area Multi-Object Fibre Spectroscopic Telescope, Sloan Extension for Galactic Understanding and Exploration, and Apache Point Observatory Galactic Evolution Experiment. The results reveal the large-scale dust distribution in the Galactic disc, showing a number of features consistent with the earlier studies. The Galactic dust disc is clearly warped and show complex structures possibly spatially associated with the Sagittarius, Local, and Perseus arms. We also provide the empirical extinction coefficients for the Gaia photometry that can be used to convert the colour excesses presented here to the line-of-sight extinction values in the Gaia photometric bands.