Alignment tests for low CMB multipoles

We investigate the large scale anomalies in the angular distribution of the cosmic microwave background radiation as measured by WMAP using several tests. These tests, based on the multipole vector expansion, measure correlations between the phases of the multipoles as expressed by the directions of the multipole vectors and their associated normal planes. We have computed the probability distribution functions for 46 such tests, for the multipoles l=2-5. We confirm earlier findings that point to a high level of alignment between l=2 (quadrupole) and l=3 (octopole), but with our tests we do not find significant planarity in the octopole. In addition, we have found other possible anomalies in the alignment between the octopole and the l=4 (hexadecupole) components, as well as in the planarity of l=4 and l=5. We introduce the notion of a total likelihood to estimate the relevance of the low-multipoles tests of non-gaussianity. We show that, as a result of these tests, the CMB maps which are most widely used for cosmological analysis lie within the ~ 10% of randomly generated maps with lowest likelihoods.Comment: References added, updated discussion on alignment with Ecliptic Plane. 12 Pages, 6 Figures. Results for additional maps, the normalized frequencies for the tests and a Mathematica Notebook that computes the tests can be found on http://fma.if.usp.br/~abramo/MVA.htm

Correlated Mixture Between Adiabatic and Isocurvature Fluctuations and Recent CMB Observations

This work presents a reduced chi^2_nu test to search for non-gaussian signals in the CMBR TT power spectrum of recent CMBR data, WMAP, ACBAR and CBI data sets, assuming a mixed density field including adiabatic and isocurvature fluctuations. We assume a skew positive mixed model with adiabatic inflation perturbations plus additional isocurvature perturbations possibly produced by topological defects. The joint probability distribution used in this context is a weighted combination of Gaussian and non-Gaussian random fields. Results from simulations of CMBR temperature for the mixed field show a distinct signature in CMB power spectrum for very small deviations (~ 0.1%) from a pure Gaussian field, and can be used as a direct test for the nature of primordial fluctuations. A reduced chi^2_nu test applied on the most recent CMBR observations reveals that an isocurvature fluctuations field is not ruled out and indeed permits a very good description for a flat geometry Lambda-CDM universe, chi^2_930 ~ 1.5, rather than the simple inflationary standard model with chi^2_930 ~ 2.3. This result may looks is particular discrepant with the reduced chi^2 of 1.07 obtained with the same model in Spergel et al. (2003) for temperature only, however, our work is restricted to a region of the parameter space that does not include the best fit model for TT only of Spergel et al. (2003).Comment: Accepted for publication in Physical Review

Testing synchrotron models and frequency resolution in BINGO 21 cm simulated maps using GNILC

To recover the 21 cm hydrogen line, it is essential to separate the cosmological signal from the much stronger foreground contributions at radio frequencies. The BINGO radio telescope is designed to measure the 21 cm line and detect BAOs using the intensity mapping technique. This work analyses the performance of the GNILC method, combined with a power spectrum debiasing procedure. The method was applied to a simulated BINGO mission, building upon previous work from the collaboration. It compares two different synchrotron emission models and different instrumental configurations, in addition to the combination with ancillary data to optimize both the foreground removal and recovery of the 21 cm signal across the full BINGO frequency band, as well as to determine an optimal number of frequency bands for the signal recovery. We have produced foreground emissions maps using the Planck Sky Model, the cosmological Hi emission maps are generated using the FLASK package and thermal noise maps are created according to the instrumental setup. We apply the GNILC method to the simulated sky maps to separate the Hi plus thermal noise contribution and, through a debiasing procedure, recover an estimate of the noiseless 21 cm power spectrum. We found a near optimal reconstruction of the Hi signal using a 80 bins configuration, which resulted in a power spectrum reconstruction average error over all frequencies of 3%. Furthermore, our tests showed that GNILC is robust against different synchrotron emission models. Finally, adding an extra channel with CBASS foregrounds information, we reduced the estimation error of the 21 cm signal. The optimisation of our previous work, producing a configuration with an optimal number of channels for binning the data, impacts greatly the decisions regarding BINGO hardware configuration before commissioning.Comment: Submitted to A&

Galactic foreground contribution to the BEAST CMB Anisotropy Maps

We report limits on the Galactic foreground emission contribution to the Background Emission Anisotropy Scanning Telescope (BEAST) Ka- and Q-band CMB anisotropy maps. We estimate the contribution from the cross-correlations between these maps and the foreground emission templates of an H${\alpha}$ map, a de-striped version of the Haslam et al. 408 MHz map, and a combined 100 $\mu$m IRAS/DIRBE map. Our analysis samples the BEAST $\sim10^\circ$ declination band into 24 one-hour (RA) wide sectors with $\sim7900$ pixels each, where we calculate: (a) the linear correlation coefficient between the anisotropy maps and the templates; (b) the coupling constants between the specific intensity units of the templates and the antenna temperature at the BEAST frequencies and (c) the individual foreground contributions to the BEAST anisotropy maps. The peak sector contributions of the contaminants in the Ka-band are of 56.5% free-free with a coupling constant of $8.3\pm0.4$ $\mu$K/R, and 67.4% dust with $45.0\pm2.0$ $\mu$K/(MJy/sr). In the Q-band the corresponding values are of 64.4% free-free with $4.1\pm0.2$ $\mu$K/R and 67.5% dust with $24.0\pm1.0$ $\mu$K/(MJy/sr). Using a lower limit of 10% in the relative uncertainty of the coupling constants, we can constrain the sector contributions of each contaminant in both maps to $< 20$% in 21 (free-free), 19 (dust) and 22 (synchrotron) sectors. At this level, all these sectors are found outside of the $\mid$b$\mid = 14.6^\circ$ region. By performing the same correlation analysis as a function of Galactic scale height, we conclude that the region within $b=\pm17.5^{\circ}$ should be removed from the BEAST maps for CMB studies in order to keep individual Galactic contributions below $\sim 1$% of the map's rms.Comment: 17 pages PostScript file. Better resolution figures can be found in the web page http://www.das.inpe.br/~alex/beast_foregrounds.html. Accepted for publication in the ApJ Suppl. Serie