the dependence of the lateral distribution of cherenkov light in simulated extensive air showers to the energy and the mass of the primary cosmic rays has been studied. it has been shown that a previous claim about mass independent proportionality of shower energy to the total cherenkov photon number is not valid in energies below eeas ~ 1014 ev. we have found that the core distance of the so c...

Motivated by the significant overdensity of background bright quasars recently detected behind the foreground clusters of galaxies on scale of 10 arcminutes, we have investigated the possibility of attributing the quasar-cluster associations to gravitational lensing by large-scale matter inhomogeneities. Based on the conventional lensing models, we have shown that the reported quasar overdensit...

We present calculations of the reflection of the cosmic X-ray background (CXB) by the Earth’s atmosphere in the 1–1000 keV energy range. The calculations include Compton scattering and X-ray fluorescent emission and are based on a realistic chemical composition of the atmosphere. Such calculations are relevant for CXB studies using the Earth as an obscuring screen (as was recently done by INTEG...

Wolfgang Kummer was a great teacher and mentor to me. Although Wolfgang never published any research on cosmology himself, he had a great interest in that field and supported me in my decision to get engaged with cosmological issues. Thus, I decided to describe current ideas and some of my own thoughts on one of the corner stones of modern cosmology — the cosmological principle. This principle ...

We review the possible sources of ionizing photons within the Local Group. Throughout most of the LG volume, the cosmic background radiation will dominate, but locally (e.g., within d ∼ 100 kpc of the Galactic disk) stellar ionizing photons escaping from galaxies may dominate. The magnitude of the cosmic ionizing background should be determined in the very near future by observations of Hα emis...

The quantum mechanical approach developed by us recently for the evolution of the universe is used to derive an alternative derivation connecting the temperature of the cosmic background radiation and the age of the universe which is found to be similar to the one obtained by Gamow long back. By assuming the age of the universe to be ≈ 20 billion years, we reproduce a value of ≈ 2.91 K for the ...