CMB as a possible new tool to study the dark baryons in galaxies
  Baryons constitute about 4% of our universe, but most of them are missing and we do not know where and in what form they are hidden. This constitute the so-called missing baryon problem. A possibility is that part of these baryons are hidden in galactic halos. We show how the 7-year data obtained by the WMAP satellite may be used to trace the halo of the nearby giant spiral galaxy M31. We detect a temperature asymmetry in the M31 halo along the rotation direction up to about 120 kpc. This could be the first detection of a galactic halo in microwaves and may open a new way to probe hidden baryons in these relatively less studied galactic objects using high accuracy CMB measurements. 
F. De Paolis, G. Ingrosso, A.A. Nucita, D. Vetrugno, V.G. Gurzadyan,   A.L. Kashin, H.G. Khachatryan, S. Mirzoyan, Ph. Jetze...
astro-ph.CO