Abstract
Two new astronomical results of the dark matter (DM) halo influence on physical processes in it are presented. We discuss Cherenkov radiation in the a galactic DM halo and the DM halo presentation as a dispersional gravitational lens. It is shown that the temperature of Cherenkov radiation in the X-ray range is about T ∼ 10−6 K, which is close to the temperature fluctuations of cosmic background radiation ΔT ∼ 10−5 K and is thus at the threshold of modern astronomical measurements. Based on the time variability of the DM state parameter, we have suggested the concept of a dispersional gravitational lens. A dependence of the DM halo refractive index on its own global oscillations was found. It is shown that DM may oscillate with the frequency ω DM ≥ 10−15 Hz. Hence, it is possible to talk about superweak DM oscillations and the existence of very cold DM particles whose mass is larger than m VCDM ≥ 10−42 eV.