Missing baryons traced by the galaxy luminosity density in the large-scale WHIM filaments

I talk about our new approach to the missing baryons problem. Building on the common assumption that the missing baryons are in the form of the Warm Hot Intergalactic Medium (WHIM), located preferentially within the large scale galaxy filaments, we further assumed that the galaxy luminosity density can be used as a tracer of the WHIM. We used hydrodynamical large scale structure simulations of Cui et al., (2012) to prove this assumption and to derive a relation between the luminosity density and the WHIM density (Nevalainen et al., 2015).  We applied our procedure to the line of sight to the blazar H2356-309 and found evidence for the WHIM in correspondence of the Sculptor Wall and Pisces-Cetus superclusters, in agreement with the redshifts and column densities of the X-ray absorbers identified and studied by Fang et al.  (2010) and Zappacosta et al. (2010). This agreement indicates that the galaxy luminosity density and galactic filaments are reliable signposts for the WHIM and that our method is robust in estimating the WHIM density.