Where have half the baryons gone?

Speakers:

Jukka Henry P Nevalainen
Tartu Observatory, Estonia

Abstract:

Concordance cosmology predicts that 4-5% of the matter of the Universe is baryonic. Yet, only 50% of these have been observed in the nearby z < 1 Universe. Simulations suggest that these "missing baryons" are in the form of Warm-Hot Intergalactic Medium (WHIM) with temperatures and densities of 10^5-6 K and 10^-6 - 10^-4 cm-3.

They are expected to be located within the Cosmic Web, the large scale filamentary structure connecting clusters and superclusters of galaxies. In the context of our WBANG project http://www.helsinki.fi/~junevala/PUT/WBANG_homepage.pdf we are searching for WHIM via its X-ray absorption effects of the background sources.

Our search is based on the known foreground filamentary galaxy structures, obtained from Sloan Digital Sky Survey, the likely sites of WHIM. I will present our methodology and preliminary results.