Unraveling the Radiative Properties of the Interstellar Medium: The First 3D Map of the Interstellar Dust Temperature

Abstract Despite making up only 1% of the mass of the interstellar medium, dust has an outsize impact on the evolution of galaxies. Dust absorbs and scatters a substantial fraction of the ultraviolet and optical light produced in a galaxy, re-radiating it in the infrared. It influences the formation and evolution of stars and planetary systems. It also serves as an astrophysical probe, providing information about magnetic field structure and the radiation field, but only if we understand its properties in 3D. Recent years have brought rapid progress in mapping dust density in 3D [1, 2, 4, 5, 45], but attempts to derive its temperature and other optical properties have been few. Here, we present the first comprehensive large-scale, three-dimensional map of dust temperature in the Milky Way. We show that this methodology has enough precision to discern temperature differences with 3σ significance along the line of sight. Star formation regions are clearly observable in the map. This technique and the resulting 3D dust temperature map open up new areas of research into models of galactic magnetic field in 3D, polarization maps, cosmological foreground analysis, cosmic ray propagation for dark matter searches, correlations with star forming regions and other data catalogs.