Evidence for dust emission in the Warm Ionised Medium using WHAM data

We have used the WHAM Hα survey and Leiden/Dwingeloo HI data to decompose the Far-infrared emission (from 100 to 1000 μm) at high Galactic latitude into components associated with the Warm Ionised Medium (WIM) and the Warm Neutral Medium (WNM). This decomposition is possible for the first time thanks to preliminary WHAM data that cover a significant fraction of the sky (about 10%). We confirm the first detection of dust emission from the WIM (Lagache et al. 1999) and show that the WIM dust temperature and emissivity are very similar to those in the WNM. The analysis suggests moreover that about 25% of the far-IR dust emission at high Galactic latitude is uncorrelated with the HI gas. The decomposition again reveals a Cosmic Far-Infrared Background (CFIRB) which is determined for the first time from 100 to 1000 μm using two independent gas tracers.