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Session 87 - Large Scale Structure.
Display session, Friday, January 09
Exhibit Hall,

[87.04] Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds

D. J. Schlegel (U. Durham, UK), D. P. Finkbeiner, M. Davis (UC Berkeley)

\newcommand\K K \newcommand\nWpMMSr nW/m^2/sr \newcommand\HIH\,\scriptsize I

We present a full sky 100\micron map that is a reprocessed composite of the COBE/DIRBE and IRAS/ISSA maps, with the zodiacal foreground and confirmed point sources removed. We have constructed a map of the dust temperature, so that the 100\micron map can be converted to a map proportional to dust column density. The dust temperature varies from 17\K to 21\K, which is modest but does modify the estimate of the dust column by a factor of 5. The result of these manipulations is a map with DIRBE-quality calibration and IRAS resolution. A wealth of filamentary detail is apparent on many different scales at all Galactic latitudes. In high latitude regions, the dust map correlates well with maps of \HI\ emission, but deviations are significant.

To generate the full sky dust maps, we must first remove zodiacal light contamination as well as a possible cosmic infrared background (CIB). For the 100\micron map no signficant CIB is detected, but in the 140\micron and 240\micron maps, where the zodiacal contamination is weaker, we detect the CIB at surprisingly high flux levels of 30 \pm 8 \nWpMMSr at 140\micron, and 16 \pm 3.4 \nWpMMSr at 240\micron (95% confidence), which is an integrated flux \sim 2 times that extrapolated from optical galaxies in the Hubble Deep Field.

The primary use of these maps is likely to be as a new estimator of Galactic extinction. To calibrate our maps, we assume a standard reddening law, and use the colors of elliptical galaxies. We demonstrate that the new maps are twice as accurate as the older Burstein-Heiles reddening estimates in regions of low and moderate reddening. The maps are expected to be significantly more accurate in regions of high reddening. These dust maps will also be useful for estimating millimeter emission that contaminates CMBR experiments and for estimating soft X-ray absorption.

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