3D extinction maps of the Milky Way disc from Gaia GSP-Spec parameters

Abstract

3D maps of interstellar dust are crucial for understanding the structure of the Milky Way interstellar medium to apply correction to astrophysical observations affected by dust. We aim at providing new extinction estimates in the Gaia BP/RP bands to study the dust distribution in the disc, to provide new views of the spatial distribution of extinction and to compare it with tracers of the Galactic spiral arms. We use a highly homogeneous method based on the spectral chemo-physical parametrisation of stars from Gaia General Stellar Parametriser-Spectroscopy (GSP-Spec). This catalogue of 5.6 million stars in DR3, presents the advantage of estimating the stellar atmospheric parameters independently of extinction. The extinction is calculated by comparing the observed stellar (BP-RP) colours in the Gaia bands with the theoretical ones assuming a theoretical Teff-log(g)-[M/H] relation, from the GSP-Spec parameters. Publicly available, 3D high-resolution maps around the Sun are produced through the computation of differential extinction by discretising the dataset into spherical coordinates. Our large scale map covers a region of 4x4x0.8 kpc centred on the Sun with a discretisation of (dr,dθ,dϕ)=(40pc,1°,1°). To exploit the higher number of stars in the Sun proximity, we created a smaller scale map focused on the Local Bubble area, with a volume of 1x1x0.8 kpc and a finer discretisation of (dr,dθ,dϕ)=(30pc,1°,1°). The produced extinction maps exhibit a strong spatial correlation with molecular clouds and the spiral arms. Interestingly, several regions of the map are consistently present in different tracers as density of gas, of young stars and the chemical pattern of the spiral arms. Our study unveils the link between the distribution of dust, gas, and stars governing the chemical and dynamical evolution of the spiral arms in the Galactic framework.