AAS 199th meeting, Washington, DC, January 2002
Session 16. Cosmology and Lensing
Display, Monday, January 7, 2002, 9:20am-6:30pm, Exhibit Hall

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[16.09] Determination of the Far Infrared Cosmic Background Allowing for Foreground Emission from the Warm Ionized Interstellar Medium

N. Odegard (RITSS & NASA/GSFC), E. Dwek (NASA/GSFC), R. G. Arendt (SSAI & NASA/GSFC), L. M. Haffner, R. J. Reynolds (U. of Wisconsin - Madison), M. G. Hauser (STScI), T. J. Sodroski (EITI & NASA/GSFC)

Determination of the cosmic infrared background (CIB) using COBE/DIRBE data is almost entirely limited by the accuracy to which foreground interplanetary and Galactic emission can be modelled and subtracted. Previous determinations of the far infrared CIB (e.g., Hauser et al. 1998, ApJ, 508, 25) were based on the detection of residual isotropic emission in skymaps from which the emission from interplanetary dust and the neutral interstellar medium (ISM) were removed. At the time of these studies the magnitude of any dust emission from the ionized ISM was not well known. This foreground emission component may affect previous determinations of the CIB in the far infrared if it is spatially uncorrelated with Galactic H I emission over the regions studied. To examine the effect of this foreground component on previous background determinations, we use the recently released Wisconsin H Alpha Mapper Northern Sky Survey as a tracer of the warm ionized medium. DIRBE far infrared data at high Galactic latitude are decomposed into a component that is correlated with H I column density, a component that is correlated with H alpha intensity, and a residual component which, if isotropic, can be identified as the CIB. The results are used to place constraints on the far infrared emissivity of the warm ionized medium and to assess the effect of this foreground on previous CIB determinations.

This research was supported by the NASA ADP program, NRA-99-OSS-01.

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