AAS 197, January 2001
Session 95. Cosmological Parameters and Evolution
Oral, Wednesday, January 10, 2001, 1:30-3:00pm, Town and Country

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[95.06] Unmasking the Baryons: Warm/Hot Gas in the Universe

L. A. Phillips (Princeton University)

Where are all the baryons in the local universe? The sum of all detected baryon reservoirs at low redshift falls a factor of two to four below the expected baryon density. Recent simulations show that a significant fraction of these missing baryons could be hiding in the form of intermediate temperature gas in large scale filaments. I have used these simulations to generate the expected average integrated X-ray spectrum from gas and compare this with observational constraints. In addition, the contribution to the X-ray background autocorrelation (ACF) and its cross-correlation (CCF) with the galaxy distribution is calculated from all sky maps of the X-ray background from gas and the corresponding galaxy map. These maps are also used to model the hardness ratio distribution of the ROSAT All-Sky Survey background. The implications of these simulation results on the observability of this gas component with recent and future mission are discussed.

If the emission from the warm/hot gas in large scale filaments is at levels predicted by the numerical simulations, then planned experiments should be able to detect it.

This research was supported in part by an award from the National Science and Engineering Research Council, Canada and a grant from Zonta International.

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