CMB low multipole alignments in the Λ\mathbf{\Lambda}CDM and Dipolar models

The dipolar model \cite{Gordon:2005ai} has attracted much interest because it may phenomenologically explain the CMB hemispherical power asymmetry found in the WMAP and Planck data. Since such a model explicitly breaks isotropy at large angular scales it is natural to wonder whether it can also explain other CMB directional anomalies. Focusing on the low $\ell$ alignments and assuming $\Lambda$CDM, we confirm that the quadrupole/octupole and the dipole/quadrupole/octupole alignments are anomalous with a significance up to $99.9\%$ C.L., for both WMAP and Planck data. Moreover, we show for the first time that such features are anomalous also in the dipolar model, roughly at the same level as in $\Lambda$CDM. We conclude that the dipolar model does not provide a better fit to the data than the $\Lambda$CDM.Comment: 13 pages, 2 figures and 4 table

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

Fast Spherical Harmonic Analysis: a quick algorithm for generating and/or inverting full sky, high resolution CMB Anisotropy maps

We present a fast algorithm for generating full sky, high resolution ($\sim 5'$) simulations of the CMB anisotropy pattern. We also discuss the inverse problem, that of evaluating from such a map the full set of $a_{\ell m}$'s and the spectral coefficients $C_\ell$. We show that using an Equidistant Cylindrical Projection of the sky substantially speeds up the calculations. Thus, generating and/or inverting a full sky, high resolution map can be easily achieved with present day computer technology.Comment: 13 pages, LaTex, 5 PostScript figures included, 1 colour plate available (PostScript version, 1.6 Mb) at http://itovf2.roma2.infn.it/natoli

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

ROMA: a map-making algorithm for polarised CMB data sets

We present ROMA, a parallel code to produce joint optimal temperature and polarisation maps out of multidetector CMB observations. ROMA is a fast, accurate and robust implementation of the iterative generalised least squares approach to map-making. We benchmark ROMA on realistic simulated data from the last, polarisation sensitive, flight of BOOMERanG.Comment: Accepted for publication in Astronomy & Astrophysics. Version with higher quality figures available at http://www.fisica.uniroma2.it/~cosmo/ROM

CMB Polarization: Scientific Case and Data Analysis Issues

We review the science case for studying CMB polarization. We then discuss the main issues related to the analysis of forth-coming polarized CMB data, such as those expected from balloon-borne (e.g. BOOMERanG) and satellite (e.g. Planck) experiments.Comment: 6 pages, 4 figures. To appear in "Astrophysical Polarized Background" Workshop Proceedings, eds. S. Cecchini, S. Cortiglioni, R. Sault and C. Sbarra, AIP, in pres