Constraints on a scale-dependent bias from galaxy clustering

We forecast the future constraints on scale-dependent parametrizations of galaxy bias and their impact on the estimate of cosmological parameters from the power spectrum of galaxies measured in a spectroscopic redshift survey. For the latter we assume a wide survey at relatively large redshifts, similar to the planned Euclid survey, as baseline for future experiments. To assess the impact of the bias we perform a Fisher matrix analysis and we adopt two different parametrizations of scale-dependent bias. The fiducial models for galaxy bias are calibrated using a mock catalogs of H$\alpha$ emitting galaxies mimicking the expected properties of the objects that will be targeted by the Euclid survey. In our analysis we have obtained two main results. First of all, allowing for a scale-dependent bias does not significantly increase the errors on the other cosmological parameters apart from the rms amplitude of density fluctuations, $\sigma_{8}$, and the growth index $\gamma$, whose uncertainties increase by a factor up to two, depending on the bias model adopted. Second, we find that the accuracy in the linear bias parameter $b_{0}$ can be estimated to within 1-2\% at various redshifts regardless of the fiducial model. The non-linear bias parameters have significantly large errors that depend on the model adopted. Despite of this, in the more realistic scenarios departures from the simple linear bias prescription can be detected with a $\sim2\,\sigma$ significance at each redshift explored. Finally, we use the Fisher Matrix formalism to assess the impact of assuming an incorrect bias model and found that the systematic errors induced on the cosmological parameters are similar or even larger than the statistical ones.Comment: new section added; conclusions unchanged; accepted for publication in PR

L\u2019 Etna: un percorso attraverso l\u2019immaginario, la consapevolezza del rischio e la gestione del territorio\u201d,

anche in, Annali della Facolt\ue0 di Economia, Catania, anno L, 2004

Polarization and energy dynamics in ultrafocused optical Kerr propagation

Developing a complete vectorial description of optical nonparaxial propagation of highly focused beams in Kerr media, we disclose a family of new phenomena. These phenomena appear to emerge as a consequence of the mutual coupling of all three components of the optical field. This circumstance, which is intrinsic to the very nature of Kerr propagation, was previously discarded on the basis of the conjecture that a reduced system is possible in which only one transverse field component interacts with the longitudinal component

The Adiabatic Piston and the Second Law of Thermodynamics

A detailed analysis of the adiabatic-piston problem reveals peculiar dynamical features that challenge the general belief that isolated systems necessarily reach a static equilibrium state. In particular, the fact that the piston behaves like a perpetuum mobile, i.e., it never stops but keeps wandering, undergoing sizable oscillations, around the position corresponding to maximum entropy, has remarkable implications on the entropy variations of the system and on the validity of the second law when dealing with systems of mesoscopic dimensions.Comment: 6 pages, 4 figures, First International Conference on Quantum Limits to the Second La

Observational constraints on the linear fluctuation growth rate

Several experiments in the near future will test dark energy through its effects on the linear growth of matter perturbations. It is therefore important to find simple and at the same time general parametrizations of the linear growth rate. We show that a simple fitting formula that generalizes previous expressions reproduces the growth function in models that allow for a growth faster than standard, as for instance in scalar-tensor models. We use data from galaxy and Lyman-$\alpha$ power spectra to constrain the linear growth rate. We find $\gamma=0.6_{-0.3}^{+0.4}$ for the growth rate index and $\eta=0.0_{-0.2}^{+0.3}$ for the additional growth parameter we introduce.Comment: 9 page

Territory and memory: The Landing of the Allies in Sicily in 1943

The concept of memory (memorial site) has gained crucial importance in recent years for the identification of places (areas) and in the affirmation of local identities. The memorial sites are areas where usually tragic events have occurred and resulted in a cultural change. In these places there are still signs of these historical events and/or tangible and intangible indications created by the society such as: monuments, obelisks, marble inscriptions, others. Sicily represents an ideal area for studying memorial sites; not only because of the number of dominations in the past centuries, but also for the significance of all places where the mafia has taken its root. These elements have caused several changes in the culture and in the landscape. Sicily is the land where \u201cOperation Husky\u201d began, in the summer of 1943. This agreement between the Americans and the British aimed at occupying Sicily, Italy after World War II. Seventy years after this operation the territory is still marked by testimonies of those tragic events. The bombing devastated buildings, which we can still acknowledge for their cultural significance. These memorial areas represent a strong testimony of the past. There are cemeteries, protecting bodies many of which are unknown; there are bunkers and other military garrisons well preserved throughout the territory. These signs must be rediscovered, to be replicated because of the contemporary geopolitical situation. As a result, in this paper we propose to identify the area of eastern Sicily suitable for a tourist itinerary in the cultural memory of the war of 1943. The idea is to encourage tourism that gives rise to real emotions and thoughts

Coupled-mode theory approach to nonlinear pulse propagation in optical fibers

The formalism of coupled-mode theory is adopted for describing nonlinear pulse propagation in optical fibers, the coupling being induced by the nonlinear part of the refractive index. This approach describes in a natural way the influence of the waveguide, and in principle allows of the possibility of investigating soliton propagation when more than one mode is excited