Pre-Inflationary Relics in the CMB?

String Theory and Supergravity allow, in principle, to follow the transition of the inflaton from pre-inflationary fast roll to slow roll. This introduces an infrared depression in the primordial power spectrum that might have left an imprint in the CMB anisotropy, if it occurred at accessible wavelengths. We model the effect extending $\Lambda$CDM with a scale $\Delta$ related to the infrared depression and explore the constraints allowed by {\sc Planck} data, employing also more conservative, wider Galactic masks in the low resolution CMB likelihood. In an extended mask with $f_{sky}=39\%$, we thus find \Delta = (0.351 \pm 0.114) \times 10^{-3} \, \mbox{Mpc}^{-1}, at $99.4\%$ confidence level, to be compared with a nearby value at $88.5\%$ with the standard $f_{sky}=94\%$ mask. With about 64 $e$--folds of inflation, these values for $\Delta$ would translate into primordial energy scales ${\cal O}(10^{14})$ GeV.Comment: 16 pages, 6 figures, 1 table. Final version to appear in Physics of the Dark Universe. Contains: more detailed discussion of galactic masking, improved estimat

The Evens and Odds of CMB Anomalies

The lack of power of large--angle CMB anisotropies is known to increase its statistical significance at higher Galactic latitudes, where a string--inspired pre--inflationary scale $\Delta$ can also be detected. Considering the Planck 2015 data, and relying largely on a Bayesian approach, we show that the effect is mostly driven by the \emph{even}--$\ell$ harmonic multipoles with $\ell \lesssim 20$, which appear sizably suppressed in a way that is robust with respect to Galactic masking, along with the corresponding detections of $\Delta$. On the other hand, the first \emph{odd}--$\ell$ multipoles are only suppressed at high Galactic latitudes. We investigate this behavior in different sky masks, constraining $\Delta$ through even and odd multipoles, and we elaborate on possible implications. We include low--$\ell$ polarization data which, despite being noise--limited, help in attaining confidence levels of about 3 $\sigma$ in the detection of $\Delta$. We also show by direct forecasts that a future all--sky $E$--mode cosmic--variance--limited polarization survey may push the constraining power for $\Delta$ beyond 5 $\sigma$.Comment: 49 pages, 19 figures. Figures and final discussion simplified, references added. Final version to appear in Physics of the Dark Univers

Hemispherical power asymmetries in the WMAP 7-year low-resolution temperature and polarization maps

We test the hemispherical power asymmetry of the WMAP 7-year low-resolution temperature and polarization maps. We consider two natural estimators for such an asymmetry and exploit our implementation of an optimal angular power spectrum estimator for all the six CMB spectra. By scanning the whole sky through a sample of 24 directions, we search for asymmetries in the power spectra of the two hemispheres, comparing the results with Monte Carlo simulations drawn from the WMAP 7-year best-fit model. Our analysis extends previous results to the polarization sector. The level of asymmetry on the ILC temperature map is found to be compatible with previous results, whereas no significant asymmetry on the polarized spectra is detected. Moreover, we show that our results are only weakly affected by the a posteriori choice of the maximum multipole considered for the analysis. We also forecast the capability to detect dipole modulation by our methodology at Planck sensitivity.Comment: 7 pages, 9 figures. Accepted for publication in MNRA

A Verilog HDL digital architecture for delay calculation

A method for the calculation of the delay between two digital signals with central frequencies in the range [20, 300] Hz is presented. The method performs a delay calculation in order to determine the bearing angle of a sound source. Computing accuracy is tested against a previous implementation of the Cross Correlation Derivative method. A Verilog RTL model of the method has been tested on a Xilinx® FPGA in order to evaluate the real performance of the method. Simulations of an ASIC design on a standard CMOS technology predict a power saving of about 25 times per delay stage over previous implementations.Fil: Chacón-Rodríguez, A.. Universidad de Mar del Plata. Laboratorio de Componentes Electrónicos; ArgentinaFil: Martín-Pirchio, F. N.. Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras; ArgentinaFil: Julian, Pedro Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; ArgentinaFil: Mandolesi, Pablo Sergio. Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras; Argentin