Comments on environmental effects in the origin of angular momenta in galaxies

We examine the orientations of galaxies in 43 rich Abell galaxy clusters belonging to superclusters and containing at least 100 members in the considered area as a function of supercluster multiplicity. It is found that the orientation of galaxies in the analyzed clusters is not random and the alignment decreases with supercluster richness, although the effect is statistically significant only for azimuthal angles. The dependence of galaxy alignment on cluster location inside or outside a supercluster and on supercluster multiplicity clearly shows the importance of environmental effects on the origin of galaxy angular momenta. The comparison with alignment of galaxies in a sample of rich Abell clusters not belonging to superclusters is made too.Comment: accepted in Odessa Astronomical Publications 2012 vol.25 p.2

Morphology and Evolution of Simulated and Optical Clusters: A Comparative Analysis

We have made a comparative study of morphological evolution in simulated DM halos and X-ray brightness distribution, and in optical clusters. Samples of simulated clusters include star formation with supernovae feedback, radiative cooling, and simulation in the adiabatic limit at three different redshifts, z = 0.0, 0.10, and 0.25. The optical sample contains 208 ACO clusters within redshift, $z \leq 0.25$. Cluster morphology, within 0.5 and 1.0 h$^{-1}$ Mpc from cluster center, is quantified by multiplicity and ellipticity. We find that the distribution of the dark matter halos in the adiabatic simulation appear to be more elongated than the galaxy clusters. Radiative cooling brings halo shapes in excellent agreement with observed clusters, however, cooling along with feedback mechanism make the halos more flattened. Our results indicate relatively stronger structural evolution and more clumpy distributions in observed clusters than in the structure of simulated clusters, and slower increase in simulated cluster shapes compared to those in the observed one. Within $z \leq 0.1$, we notice an interesting agreement in the shapes of clusters obtained from the cooling simulations and observation. We also notice that the different samples of observed clusters differ significantly in morphological evolution with redshift. We highlight a few possibilities responsible for the discrepancy in morphological evolution of simulated and observed clusters.Comment: Accepted for publication in MNRAS, 2006; 15 pages, 13 postscript figure

Stopnie naukowe w carskiej Rosji

Numerous Polish scientists were conferred with scientific degrees in Imperial Russia. It is therefore useful to known what kind of hierarchy these degrees followed.Wielu polskich uczonych uzyskiwało stopnie naukowe w uniwersytetach carskiej Rosji. W związku z powyższym pozwalamy sobie na przypomnienie akademickiej hierarchii w carskiej Rosji, które przydać się może osobom zainteresowanym historią nauki