Beltrami equation and cluster lensing: characteristic equations and applications

Arclets in clusters of galaxies can be used to determine the lens mapping and not only to constrain the mass density of the cluster. Multiply imaged arclets are therefore easily identified without further modelling

Isospin dependent kaon and antikaon optical potentials in dense hadronic matter

Isospin effects on the optical potentials of kaons and antikaons in dense hadronic matter are investigated using a chiral SU(3) model. These effects are important for asymmetric heavy ion collision experiments. In the present work the dispersion relations are derived for kaons and antikaons, compatible with the low energy scattering data, within our model approach. The relations result from the kaonic interactions with the nucleons, vector mesons and scalar mesons in the asymmetric nuclear matter. The isospin asymmetry effects arising from the interactions with the vector-isovector $\rho$- meson as well as the scalar isovector $\delta$ mesons are considered. The density dependence of the isospin asymmetry is seen to be appreciable for the kaon and antikaon optical potentials. This can be particularly relevant for the future accelerator facility FAIR at GSI, where experiments using neutron rich beams are planned to be used in the study of compressed baryonic matter.Comment: 21 pages, 7 figure

Constraining the size of the narrow line region in distant quasars

We propose a proper method to measure the size of the narrow line region (NLR) in distant quasars. The apparent angular size of the NLR is, in general, too small to resolve technically. However, it is possible to map the NLR if with gravitational lensing. In our method, we directly compare the observed image of the NLR with the expected lensed images of the NLR for various source sizes and lens models. Seeking the best fit image via the comparison procedures, we can obtain the best-fit size and the best-fit lens model. We apply this method to the two-dimensional spectroscopic data of a famous lensed quasar, Q2237+0305. If the lens galaxy resembles the applied lens model, an upper limit to the NLR size can be set 750 pc. Further, we examine how the fitting results will be improved by future observations, taking into account the realistic observational effects, such as seeing. Future observations will provide us more stringent constraints on the size of the NLR and on the density profile of the lens galaxy.Comment: 17 pages including 4 figures, accepted to Ap

Properties and Stability of Hybrid Stars

We discuss the properties of neutron stars and their modifications due to the occurrence of hyperons and quarks in the core of the star. More specifically, we consider the general problem of exotic particles inside compact stars in light of the observed two-solar mass pulsar. In addition, we investigate neutron star cooling and a possible explanation of the recently measured cooling curve of the neutron star in the supernova remnant Cas A.Comment: Contribution to SQM 2011 in Krak\'o

Cosmological structure formation from soft topological defects

Some models have extremely low-mass pseudo-Goldstone bosons that can lead to vacuum phase transitions at late times, after the decoupling of the microwave background.. This can generate structure formation at redshifts z greater than or approx 10 on mass scales as large as M approx 10 to the 18th solar masses. Such low energy transitions can lead to large but phenomenologically acceptable density inhomogeneities in soft topological defects (e.g., domain walls) with minimal variations in the microwave anisotropy, as small as delta Y/T less than or approx 10 to the minus 6 power. This mechanism is independent of the existence of hot, cold, or baryonic dark matter. It is a novel alternative to both cosmic string and to inflationary quantum fluctuations as the origin of structure in the Universe