Studying stellar halos with future facilities

Stellar halos around galaxies retain fundamental evidence of the processes which lead to their build up. Sophisticated models of galaxy formation in a cosmological context yield quantitative predictions about various observable characteristics, including the amount of substructure, the slope of radial mass profiles and three dimensional shapes, and the properties of the stellar populations in the halos. The comparison of such models with the observations provides constraints on the general picture of galaxy formation in the hierarchical Universe, as well as on the physical processes taking place in the halos formation. With the current observing facilities, stellar halos can be effectively probed only for a limited number of nearby galaxies. In this paper we illustrate the progress that we expect in this field with the future ground based large aperture telescopes (E-ELT) and with space based facilities as JWST.Comment: 6 pages, 4 figures, to appear in Proc. IAU Symposium 317 "The General Assembly of Stellar Halos: Structure, Origin and Evolution.

A Note on Dielectric Lenses

Spherical and cylindrical dielectric lenses - geometrical propertie

High frequency scattering from a coated cylinder

High frequency scattering produced by plane electromagnetic wave incident on coated cylinde

The BH mass of nearby QSOs: a comparison of the bulge luminosity and virial methods

We report on the analysis of the photometric and spectroscopic properties of a sample of 29 low redshift (z<0.6) QSOs for which both HST WFPC2 images and ultraviolet HST FOS spectra are available. For each object we measure the R band absolute magnitude of the host galaxy, the CIV (1550A) line width and the 1350A continuum luminosity. From these quantities we can estimate the black hole (BH) mass through the M(BH)-L(bulge) relation for inactive galaxies, and from the virial method based on the kinematics of the regions emitting the broad lines. The comparison of the masses derived from the two methods yields information on the geometry of the gas emitting regions bound to the massive BH. The cumulative distribution of the line widths is consistent with that produced by matter laying in planes with inclinations uniformly distributed between 10 and 50 deg, which corresponds to a geometrical factor f=1.3. Our results are compared with those of the literature and discussed within the unified model of AGN.Comment: 10 pages, 6 figures. To appear in MNRA

Ricerche di supersimmetria con il rivelatore ATLAS

The search for light supersymmetric partners of the top quark (stop squark) could result into the early discovery of physics beyond the Standard Model at the LHC. In this thesis, an analysis based on ATLAS simulated data is presented to study the possibility to discover scalar top quarks at the LHC. A benchmark model in the framework of the Minimal Supersymmetric Standard Model is considered, with a stop squark lighter than the top quark, yielding a final state similar to the one for $tar{t}$ production. We demonstrate that a significant excess of signal events can be extracted with 2 fb-1 of data obtained with the parametrized detector simulation. A technique to subtract the SM background based on the data is developed to achieve this result. The detailed detector simulation has also been used to study trigger and detector effects, confirming the possibility to subtract the background from the data

Cylindrical Resonator Sectorally Filled With DNG Metamaterial and Excited by a Line Source

A circular cylindrical resonator with metallic walls is analyzed in the phasor domain. The resonator contains a wedge of double-negative (DNG) metamaterial that is anti-isorefractive to the double-positive (DPS) material filling the remaining volume of the resonator, and whose edge is located on the resonator axis. The resonance conditions are established. The problem of an electric line source parallel to the axis and located anywhere inside the DPS region is solved exactly. Numerical results are presented and discusse

Cylindrical resonator filled with four alternating sectors of DPS and DNG materials

A circular cylindrical metallic resonator with four alternating sectors of DPS and DNG materials is analyzed, in the frequency domain. The two materials are linear, lossless, homogeneous, and anti-isorefractive to each other. The electric field is assumed to be parallel to the cylinder axis. It is also shown that the resonator's dispersion relation is always satisfied for particular geometries. Numerical results for several sectors' combinations will be presented and discussed at the conferenc

Theory of biaxial graded-index optical fiber

The problem of wave propagation in a biaxial graded-index fiber with circular symmetry is considered. The problem is formulated in terms of four first-order differential equations for the tangential components of the electric and magnetic fields. A general solution method for solving systems of differential equations is presented. This solution method is then used to solve the system of equations for a particular example of a biaxial graded-index fiber. Numerical results for the propagation constant in the fiber are also given