Searching for Baryons with Chandra

Abstract

At low redshifts, measurements of the total baryon content in stars, atomic and molecular hydrogen, and cluster gas fall a factor of two to four below the baryon density derived from observed light-element ratios and nucleosynthesis arguments. A possible hiding place for a significant fraction of the missing baryons is in the warm/hot gas at temperatures T = 10^{5}-10^{7}K. We present predictions of the contribution to the soft X-ray background from warm/hot gas emission calculated using new hydrodynamical simulations and discuss the possibility of detecting the spectral signature of this gas using the Chandra X-ray Observatory.

6 pages, 2 figures, poster presentation to be published in the proceedings of "X-ray Astronomy 2000", eds. R. Giacconi, L. Stella & S. Serio