Dark baryons and the profile crisis in cold dark matter halos

This Letter proposes that the "profile crisis" in cold dark matter halo models is partly due to a weakly dissipative dark baryonic component. This component is built by rescaling the rotation curves of faint galaxies onto those of bright systems, and we argue that the collapse factor of the baryonic disk relative to the halo must be a constant. If this component is made of molecular gas in a frozen form, a large hole is expected in the central region that is due to UV heating by the stellar component. This hole, combined with a weakly peaked distribution of halo particles, may mimic an isothermal halo core that is wrongly attributed to the particles alone. Halos made of cold particles with or without a finite-scattering cross section are considered in this context. For faint objects, a concordance model is achieved with roughly half the mass in baryons, a mass concentration c(M) approximate to 6.2 +/- 0.5, and a inner profile rho proportional to r(-0.5 +/-0.3) at r = 0 for the halos.