Large Scale Peculiar Velocities: Effects from Superclusters

We study the gravitational influence of very large scale structures, as traced by clusters of galaxies, on the Local Group [LG] motion and the large scale flows. We derive from the distribution of Abell clusters within $300~$Mpc/h the overdensity field on a 3--D grid of spacing $5~$Mpc/h, then we solve the Poisson equation for the peculiar potential and finally obtain the peculiar velocity field. Quite interestingly, from this global solution we: i) recover within $\sim 10^o$ the direction of the LG motion in the Cosmic Microwave Background [CMB] frame, ii find that the Great Attractor itself moves wrt to the CMB frame, iii) derive $\beta_c^{-1} \equiv b_c \Omega_0^{-0.6} = 5.3 \pm 0.20$ from a preliminary comparison with the Mark~II catalog of peculiar velocities, iv) derive estimates for the bulk flow in spheres which fairly agree with the level derived from POTENT and the Spiral samples, v) find that the Lauer \& Postman [L\&P] bulk flow has too a large amplitude to be in agreement with our results.Comment: To appear in XXXth Moriond "Clustering in the Universe". Four, uuencoded, compressed (gzip -9), self unpacking postscript pages (figures included). [if you want an hardcopy of Ref.5, please send an E-mail to [email protected]

Measuring primordial non-gaussianity without cosmic variance

Non-gaussianity in the initial conditions of the universe is one of the most powerful mechanisms to discriminate among the competing theories of the early universe. Measurements using bispectrum of cosmic microwave background anisotropies are limited by the cosmic variance, i.e. available number of modes. Recent work has emphasized the possibility to probe non-gaussianity of local type using the scale dependence of large scale bias from highly biased tracers of large scale structure. However, this power spectrum method is also limited by cosmic variance, finite number of structures on the largest scales, and by the partial degeneracy with other cosmological parameters that can mimic the same effect. Here we propose an alternative method that solves both of these problems. It is based on the idea that on large scales halos are biased, but not stochastic, tracers of dark matter: by correlating a highly biased tracer of large scale structure against an unbiased tracer one eliminates the cosmic variance error, which can lead to a high signal to noise even from the structures comparable to the size of the survey. The square of error improvement on non-gaussianity parameter f_nl relative to the power spectrum method scales as Pn/2, where P and n is the power spectrum and the number density of the biased tracer, respectively. For an ideal survey out to z=2 the error reduction can be as large as a factor of seven, which should guarantee a detection of non-gaussianity from an all sky survey of this type. The improvements could be even larger if high density tracers that are sensitive to non-gaussianity can be identified and measured over a large volume.Comment: 7 page

Testing the distance duality relation with present and future data

The assumptions that "light propagates along null geodesics of the spacetime metric" and "the number of photons is conserved along the light path" lead to the distance duality relation (DDR), $\eta = D_L(z) (1 + z)^{-2}/D_A(z) = 1$, with $D_L(z)$ and $D_A(z)$ the luminosity and angular diameter distances to a source at redshift $z$. In order to test the DDR, we follow the usual strategy comparing the angular diameter distances of a set of clusters, inferred from X - ray and radio data, with the luminosity distance at the same cluster redshift using the local regression technique to estimate $D_L(z)$ from Type Ia Supernovae (SNeIa) Hubble diagram. In order to both strengthen the constraints on the DDR and get rid of the systematics related to the unknown cluster geometry, we also investigate the possibility to use Baryon Acoustic Oscillations (BAO) to infer $D_A(z)$ from future BAO surveys. As a test case, we consider the proposed Euclid mission investigating the precision can be afforded on $\eta(z)$ from the expected SNeIa and BAO data. We find that the combination of BAO and the local regression coupled allows to reduce the errors on $\eta_a = d\eta/dz|_{z = 0}$ by a factor two if one $\eta_0 = \eta(z = 0) = 1$ is forced and future data are used. On the other hand, although the statistical error on $\eta_0$ is not significantly reduced, the constraints on this quantity will be nevertheless ameliorated thanks to the reduce impact of systematics.Comment: 10 pages, 1 figure, 1 table, accepted for publication on Physical Review

Ramón Cornavaca. "El Simposio platónico en tres obras de Leopoldo Marechal" En: La intertextualidad desde el punto de vista de la literatura comparada. Córdoba, Talleres Gráficos de José Solsona, 1993, pp. 11-17.

Fil: Scaramella, Dora G.. Universidad Nacional de Cuyo. Facultad de Filosofía y Letra

Increasing the lensing figure of merit through higher order convergence moments

The unprecedented quality, the increased data set, and the wide area of ongoing and near future weak lensing surveys allows one to move beyond the standard two points statistics, thus making it worthwhile to investigate higher order probes. As an interesting step toward this direction, we explore the use of higher order moments (HOM) of the convergence field as a way to increase the lensing figure of merit (FoM). To this end, we rely on simulated convergence to first show that HOM can be measured and calibrated so that it is indeed possible to predict them for a given cosmological model provided suitable nuisance parameters are introduced and then marginalized over. We then forecast the accuracy on cosmological parameters from the use of HOM alone and in combination with standard shear power spectra tomography. It turns out that HOM allow one to break some common degeneracies, thus significantly boosting the overall FoM. We also qualitatively discuss possible systematics and how they can be dealt with

Los hápax en la literatura

Fil: Scaramella, Dora G.. Universidad Nacional de Cuyo. Facultad de Filosofía y Letra

El concepto de conjunto económico según la ley del impuesto a las ganancias

La complejidad del mundo de los negocios y las cambiantes circunstancias de los mercados hace, en muchos casos, que los empresarios deban replantear la organización de sus emprendimientos para lograr diversos objetivos: reducción de costos, eficientización de procesos, mejora en el posicionamiento de la empresa, acceso a otros mercados, etc. Estas reorganizaciones, en la medida que impliquen la aparición de nuevos entes económicos o el cese de otros y la transferencia de patrimonios, pueden acarrear consecuencias tributariasFil: Mantovan Scaramella, Flavio. Universidad Nacional de Cuyo. Facultad de Ciencias Económica