Local interstellar radiation field

The LISRF was extrapolated from the optical to the ultraviolet and near-infrared, using the astrophysical parameters provided by DR3 for a subsample of Gaia stars. The correlation between dust emission at 100um and residual diffuse emission in the Pioneer and other available maps was exploited to derive the contribution of dust-scattered starlight to the LISRF. The new LISRF is significantly redder and emits ~30% more energy than the old model.

The old LISRF is almost a factor two lower in the near-infrared (NIR), while, in the optical, it accounts only for direct starlight. For |b|<50 degree diffuse starlight contributes on average to ~25% of the total radiation, which is three times more than what can be derived using literature estimates at high Galactic latitudes. Conclusions: The new LISRF can modify the predicted mid-infrared (MIR) dust emission beyond the uncertainties normally assumed between dust models and observational constraints.

These differences should be taken into account to redefine the properties of small grains and of carriers of the MIR emission bands.