Testing 3+1 and 3+2 neutrino mass models with cosmology and short baseline experiments

Recent results from short--baseline neutrino oscillation experiments and Cosmic Microwave Background anisotropy measurements suggest the presence of additional sterile neutrinos. In this paper we properly combine these data sets to derive bounds on the sterile neutrino masses in the 3+1 and 3+2 frameworks, finding a potentially good agreement between the two datasets. However, when galaxy clustering is included in the analysis a tension between the oscillation and cosmological data is clearly present

Future CMB cosmological constraints in a dark coupled universe

Cosmic Microwave Background satellite missions as the on-going Planck experiment are expected to provide the strongest constraints on a wide set of cosmological parameters. Those constraints, however, could be weakened when the assumption of a cosmological constant as the dark energy component is removed. Here we show that it will indeed be the case when there exists a coupling among the dark energy and the dark matter fluids. In particular, the expected errors on key parameters as the cold dark matter density and the angular diameter distance at decoupling are significantly larger when a dark coupling is introduced. We show that it will be the case also for future satellite missions as EPIC, unless CMB lensing extraction is performed.Comment: 6 pages, 6 figure

Online trajectory planning and filtering for robotic applications via B-spline smoothing filters

In this paper, a novel technique for online generating trajectories in the 3-D space is presented. The trajectory planner is based on cubic B-splines. However, while the definition of B-splines requires the solution of a global problem that involves the entire set of via-points to be interpolated/ approximated, and therefore it is not suitable for online implementation, the proposed generator is able to approximate spline functions with the prescribed precision on the basis of local computations, which only need the knowledge of a very limited number of via-points. FIR filters are the foundation of this result. As a matter of fact the planner is composed by a first FIR filter for the computation of the control points from the sequence of desired via-points, followed by a chain of moving average filters. Therefore, the generator combines the characteristics of B-spline trajectories (smoothness and minimum curvature) and those of FIR filters (simple structure and computational efficiency). Moreover, besides standard cubic curves, the so-called smoothing B-splines have been considered for online trajectory generation. This allows to find a tradeoff between the possibility of exactly crossing the given via-points and the smoothness of the resulting trajectory. A simple teleoperation task with a Puma 560 industrial manipulator has been arranged for experimentally validating the proposed method. \ua9 2013 IEEE

Constraining Variations in the Fine Structure Constant in the presence of Early Dark Energy

We discuss present and future cosmological constraints on variations of the fine structure constant $\alpha$ induced by an early dark energy component having the simplest allowed (linear) coupling to electromagnetism. We find that current cosmological data show no variation of the fine structure constant at recombination respect to the present-day value, with $\alpha$ / $\alpha_0$ = 0.975 \pm 0.020 at 95 % c.l., constraining the energy density in early dark energy to $\Omega_e$ < 0.060 at 95 % c.l.. Moreover, we consider constraints on the parameter quantifying the strength of the coupling by the scalar field. We find that current cosmological constraints on the coupling are about 20 times weaker than those obtainable locally (which come from Equivalence Principle tests). However forthcoming or future missions, such as Planck Surveyor and CMBPol, can match and possibly even surpass the sensitivity of current local tests.Comment: 5 pages, 3 figure

Constraints on a New Post-General Relativity Cosmological Parameter

A new cosmological variable is introduced which characterizes the degree of departure from Einstein's General Relativity (GR) with a cosmological constant. The new parameter, \varpi, is the cosmological analog of \gamma, the parametrized post-Newtonian variable which measures the amount of spacetime curvature per unit mass. In the cosmological context, \varpi measures the difference between the Newtonian and longitudinal potentials in response to the same matter sources, as occurs in certain scalar-tensor theories of gravity. Equivalently, \varpi measures the scalar shear fluctuation in a dark energy component. In the context of a "vanilla" LCDM background cosmology, a non-zero \varpi signals a departure from GR or a fluctuating cosmological constant. Using a phenomenological model for the time evolution \varpi=\varpi_0 \rho_{DE}/\rho_{M} which depends on the ratio of energy density in the cosmological constant to the matter density at each epoch, it is shown that the observed cosmic microwave background (CMB) temperature anisotropies limit the overall normalization constant to be -0.4 < \varpi_0 < 0.1 at the 95% confidence level. Existing measurements of the cross-correlations of the CMB with large-scale structure further limit \varpi_0 > -0.2 at the 95% CL. In the future, integrated Sachs-Wolfe and weak lensing measurements can more tightly constrain \varpi_0, providing a valuable clue to the nature of dark energy and the validity of GR.Comment: 9 pages, 7 figures; added reference

An improved limit on the neutrino mass with CMB and redshift-dependent halo bias-mass relations from SDSS, DEEP2, and Lyman-Break Galaxies

We use measurements of luminosity-dependent galaxy bias at several different redshifts, SDSS at $z=0.05$, DEEP2 at $z=1$ and LBGs at $z=3.8$, combined with WMAP five-year cosmic microwave background anisotropy data and SDSS Red Luminous Galaxy survey three-dimensional clustering power spectrum to put constraints on cosmological parameters. Fitting this combined dataset, we show that the luminosity-dependent bias data that probe the relation between halo bias and halo mass and its redshift evolution are very sensitive to sum of the neutrino masses: in particular we obtain the upper limit of $\sum m_{\nu}<0.28$eV at the 95% confidence level for a $\Lambda CDM + m_{\nu}$ model, with a $\sigma_8$ equal to $\sigma_8=0.759\pm0.025$ (1$\sigma$). When we allow the dark energy equation of state parameter $w$ to vary we find $w=-1.30\pm0.19$ for a general $wCDM+m_{\nu}$ model with the 95% confidence level upper limit on the neutrino masses at $\sum m_{\nu}<0.59$eV. The constraint on the dark energy equation of state further improves to $w=-1.125\pm0.092$ when using also ACBAR and supernovae Union data, in addition to above, with a prior on the Hubble constant from the Hubble Space Telescope.Comment: 9 pages, 6 figures, submitted to PR

The Fine Structure Constant and the CMB Damping Scale

The recent measurements of the Cosmic Microwave Background anisotropies at arcminute angular scales performed by the ACT and SPT experiments are probing the damping regime of CMB fluctuations. The analysis of these datasets unexpectedly suggests that the effective number of relativistic degrees of freedom is larger than the standard value of Neff = 3.04, and inconsistent with it at more than two standard deviations. In this paper we study the role of a mechanism that could affect the shape of the CMB angular fluctuations at those scales, namely a change in the recombination process through variations in the fine structure constant. We show that the new CMB data significantly improve the previous constraints on variations of {\alpha}, with {\alpha}/{\alpha}0 = 0.984 \pm 0.005, i.e. hinting also to a more than two standard deviation from the current, local, value {\alpha}0. A significant degeneracy is present between {\alpha} and Neff, and when variations in the latter are allowed the constraints on {\alpha} are relaxed and again consistent with the standard value. Deviations of either parameter from their standard values would imply the presence of new, currently unknown physics.Comment: 4 pages, 1 figur

Space Robotics: an Experimental Set-up based on RTAI-Linux

In space application, it is of great interest the development of autonomous or semi-autonomous robotic devices that can substitute the astronauts in routine operations in order to free them from repetitive tasks and reduce mission costs. In this work, an experimental setup based on a 6 degrees of freedom (dof) manipulator with a 3 dof gripper designed for a possible application within PaT, the Payload Tutor proposed by ASI (Italian Space Agency), is presented. This system consists of a robotic arm, a vision system, and a gripper. Since the gripper has to interact with free-floating and irregular objects, the vision subsystem provides all the information needed for grasping unknown objects in an optimal way