Showing papers by "Paolo Natoli published in 2009"
TL;DR: In this article, a formalism to include the reported calibration uncertainties of the BOOMERanG focal plane was developed and applied to the B2K dataset, finding a cosmological rotation angle of 4.4.
Abstract: Cosmic microwave background experiments must achieve very accurate calibration of their polarization reference frame to avoid biasing the cosmological parameters. In particular, a wrong or inaccurate calibration might mimic the presence of a gravitational wave background, or a signal from cosmological birefringence, a phenomenon characteristic of several nonstandard, symmetry breaking theories of electrodynamics that allow for in vacuo rotation of the polarization direction of the photon. Noteworthly, several authors have claimed that the BOOMERanG 2003 (B2K) published polarized power spectra of the cosmic microwave background may hint at cosmological birefringence. Such analyses, however, do not take into account the reported calibration uncertainties of the BOOMERanG focal plane. We develop a formalism to include this effect and apply it to the BOOMERanG dataset, finding a cosmological rotation angle $\ensuremath{\alpha}=\ensuremath{-}4.3\ifmmode^\circ\else\textdegree\fi{}\ifmmode\pm\else\textpm\fi{}4.1\ifmmode^\circ\else\textdegree\fi{}$. We also investigate the expected performances of future space borne experiment, finding that an overall miscalibration larger then 1\ifmmode^\circ\else\textdegree\fi{} for Planck and 0.2\ifmmode^\circ\else\textdegree\fi{} for the Experimental Probe of Inflationary Cosmology, if not properly taken into account, will produce a bias on the constraints on the cosmological parameters and could misleadingly suggest the presence of a gravitational waves background.
77 citations
TL;DR: In this article, the authors investigated the impact of a nonstandard time evolution of the dark matter component on current cosmological bounds from cosmic microwave background (CMB) anisotropies, finding that less than 0.1% variation in the effective dark matter equation of state w{sub dm} can drastically change current CMB bounds on the matter density, the Hubble parameter and the age of the universe.
Abstract: We investigate the impact of a nonstandard time evolution of the dark matter component on current cosmological bounds from cosmic microwave background (CMB) anisotropies. We found that a less than 0.1% variation in the effective dark matter equation of state w{sub dm} can drastically change current CMB bounds on the matter density, the Hubble parameter and the age of the Universe. A flat universe without dark energy could provide an excellent fit to current CMB data, providing that w{sub dm}{approx}-10{sup -2}.
31 citations
University of Helsinki1, Helsinki Institute of Physics2, California Institute of Technology3, University of Cambridge4, University of Rome Tor Vergata5, Sapienza University of Rome6, Lawrence Berkeley National Laboratory7, Helsinki University of Technology8, Paris Diderot University9, University of California, Berkeley10, INAF11, University of Oslo12, University of Warsaw13, Institut d'Astrophysique de Paris14, Imperial College London15, Spanish National Research Council16
TL;DR: In this article, the authors derived analytical estimates of covariance of the residual noise contained in low-resolution maps produced using a number of map-making approaches and test these analytical predictions using Monte Carlo simulations and their impact on angular power spectrum estimation.
Abstract: Aims: Develop and validate tools to estimate residual noise covariance in Planck frequency maps. Quantify signal error effects and compare different techniques to produce low-resolution maps.
Methods: We derive analytical estimates of covariance of the residual noise contained in low-resolution maps produced using a number of map-making approaches. We test these analytical predictions using Monte Carlo simulations and their impact on angular power spectrum estimation. We use simulations to quantify the level of signal errors incurred in different resolution downgrading schemes considered in this work.
Results: We find an excellent agreement between the optimal residual noise covariance matrices and Monte Carlo noise maps. For destriping map-makers, the extent of agreement is dictated by the knee frequency of the correlated noise component and the chosen baseline offset length. The significance of signal striping is shown to be insignificant when properly dealt with. In map resolution downgrading, we find that a carefully selected window function is required to reduce aliasing to the sub-percent level at multipoles, ell > 2Nside, where Nside is the HEALPix resolution parameter. We show that sufficient characterization of the residual noise is unavoidable if one is to draw reliable contraints on large scale anisotropy.
Conclusions: We have described how to compute the low-resolution maps, with a controlled sky signal level, and a reliable estimate of covariance of the residual noise. We have also presented a method to smooth the residual noise covariance matrices to describe the noise correlations in smoothed, bandwidth limited maps.
14 citations
University of Rome Tor Vergata1, Cardiff University2, Princeton University3, University of Texas at Austin4, Jet Propulsion Laboratory5, University of Toronto6, Lawrence Berkeley National Laboratory7, Space Sciences Laboratory8, International Federation of Accountants9, Imperial College London10, Sapienza University of Rome11, Massachusetts Institute of Technology12, National Institute of Geophysics and Volcanology13, California Institute of Technology14, Case Western Reserve University15, INAF16
TL;DR: In this article, a perturbative expansion of the Minkowski function in the limit of a weakly non-Gaussian field yields analytical formulae, derived by Hikage et al. (2006), which can be used to constrain the coupling parameter f_NL without the need for nonGaussian simulations.
Abstract: We use Minkowski Functionals (MF) to constrain a primordial non-Gaussian contribution to the CMB intensity field as observed in the 150 GHz and 145 GHz BOOMERanG maps from the 1998 and 2003 flights, respectively, performing for the first time a joint analysis of the two datasets. A perturbative expansion of the MF formulae in the limit of a weakly non-Gaussian field yields analytical formulae, derived by Hikage et al. (2006), which can be used to constrain the coupling parameter f_NL without the need for non-Gaussian simulations. We find -1020
13 citations
Sapienza University of Rome1, University of California, Irvine2, Paris Diderot University3, University of Portsmouth4, University of Rome Tor Vergata5, Cardiff University6, California Institute of Technology7, University of Toronto8, Lawrence Berkeley National Laboratory9, International Federation of Accountants10, Imperial College London11, Massachusetts Institute of Technology12, National Institute of Geophysics and Volcanology13, Institut d'Astrophysique de Paris14, Princeton University15, Case Western Reserve University16, University of California, Berkeley17
TL;DR: In this paper, an upper bound of 15.3 μK (2σ) for rms SZ fluctuations in a broad bin between multipoles of 250 and 1200 at the Rayleigh-Jeans (RJ) end of the spectrum was obtained.
Abstract: The Sunyaev-Zel'dovich (SZ) effect is the inverse Compton-scattering of cosmic microwave background (CMB) photons by hot electrons in the intervening gas throughout the universe. The effect has a distinct spectral signature that allows its separation from other signals in multifrequency CMB data sets. Using CMB anisotropies measured at three frequencies by the BOOMERANG 2003 flight we constrain SZ fluctuations in the 10 arcmin to 1 deg angular range. Propagating errors and potential systematic effects through simulations, we obtain an overall upper limit of 15.3 μK (2σ) for rms SZ fluctuations in a broad bin between multipoles of 250 and 1200 at the Rayleigh-Jeans (RJ) end of the spectrum. The resulting upper limit on the local universe normalization of the density perturbations with BOOMERANG SZ data alone is σSZ 8 < 1.14 at the 95% confidence level. When combined with other CMB anisotropy and SZ measurements, we find σSZ 8 < 0.92 (95% c.l.).
11 citations
University of California, Irvine1, Sapienza University of Rome2, Paris Diderot University3, University of Rome Tor Vergata4, University of Portsmouth5, Cardiff University6, California Institute of Technology7, University of Toronto8, Lawrence Berkeley National Laboratory9, International Federation of Accountants10, Imperial College London11, Massachusetts Institute of Technology12, National Institute of Geophysics and Volcanology13, Institut d'Astrophysique de Paris14, Princeton University15, Case Western Reserve University16, University of California, Berkeley17
TL;DR: In this paper, an upper bound of 15.3 uK (2 sigma) for rms SZ fluctuations in a broad bin between multipoles of of 250 and 1200 at the Rayleigh-Jeans (RJ) end of the spectrum was obtained.
Abstract: The Sunyaev-Zel'dovich (SZ) effect is the inverse Compton-scattering of cosmic microwave background (CMB) photons by hot electrons in the intervening gas throughout the universe. The effect has a distinct spectral signature that allows its separation from other signals in multifrequency CMB datasets. Using CMB anisotropies measured at three frequencies by the BOOMERanG 2003 flight we constrain SZ fluctuations in the 10 arcmin to 1 deg angular range. Propagating errors and potential systematic effects through simulations, we obtain an overall upper limit of 15.3 uK (2 sigma) for rms SZ fluctuations in a broad bin between multipoles of of 250 and 1200 at the Rayleigh-Jeans (RJ) end of the spectrum. When combined with other CMB anisotropy and SZ measurements, we find that the local universe normalization of the density perturbations is sigma-8(SZ) < 0.96 at the 95% confidence level, consistent with sigma-8 determined from primordial perturbations.
8 citations