Observational consequences of baryonic gaseous dark matter

Abstract

Possible observational consequences of dark matter in the Galaxy in the form of dense molecular gas clouds - clumpuscules of masses $M_c\sim 10^{-3} \msun$ and radii $R_c\sim 3\times 10^{13}$ cm - are considered. Recent models of the extreme scattering events - refraction of radio-waves from quasars in dense plasma clumps in the Galactic halo - definitely show on such clouds as possible dark matter candidate. We argue that collisions of such clumpuscules are quite frequent: around $1-10 \msun$ a year can be ejected in the interstellar medium due to collisions. Optical continuum and 21 cm emissions from post-collisional gas are found to be observable. We show that clumpuscules can form around O stars HII regions of sizes $R\sim 30$ pc and emission measure $EM\simeq 20 cm^{-6}$ pc, and can also be observable in $H_α$ emission. Evaporation of clumpuscules by external ionizing radiation can be a substantial mass source. From requirement that the total mass input on the Hubble time cannot exceed the luminous mass in the Galaxy, typical radius of clouds is constrained as $R_c < 3.5\times 10^{12}$ cm, and their contribution to surface mass density as 50 $\msun pc^{-2}$. It is argued that dissipation of kinetic energy of the gas ejected by such clouds can be an efficient energy source for the Galactic halo.