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Astron. Astrophys. 354, 247-252 (2000)

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

G. Lagache 1, L.M. Haffner 2, R.J. Reynolds 2 and S.L. Tufte 3

1 Institut d'Astrophysique Spatial, Bât. 121, Université Paris XI, 91405 Orsay Cedex, France
2 University of Wisconsin, Astronomy Department, Madison, WI 53706, USA
3 Lewis & Clark College, Department of Physics, Portland, OR 97219, USA

Received 26 August 1999 / Accepted 19 November 1999


We have used the WHAM [FORMULA] 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[FORMULA]). 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[FORMULA] 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.

Key words: ISM: dust, extinction – infrared: ISM: continuum – ISM: general

Send offprint requests to: lagache@ias.fr

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© European Southern Observatory (ESO) 2000

Online publication: January 31, 2000