arXiv subjects

S. Plaszczynski

Publications and source records attributed to S. Plaszczynski.

27 records · Page 2Linked to original sources

arXiv2010

Planck pre-launch status: High Frequency Instrument polarization calibration

The High Frequency Instrument of Planck will map the entire sky in the millimeter and sub-millimeter domain from 100 to 857 GHz with unprecedented sensitivity to polarization ($ΔP/T_{\tiny cmb} \sim 4\cdot 10^{-6}$) at 100, 143, 217 and 353 GHz. It will lead to major improvements in our understanding of the Cosmic Microwave Background anisotropies and polarized foreground signals. Planck will make high resolution measurements of the $E$-mode spectrum (up to $\ell \sim 1500$) and will also play a prominent role in the search for the faint imprint of primordial gravitational waves on the CMB polarization. This paper addresses the effects of calibration of both temperature (gain) and polarization (polarization efficiency and detector orientation) on polarization measurements. The specific requirements on the polarization parameters of the instrument are set and we report on their pre-flight measurement on HFI bolometers. We present a semi-analytical method that exactly accounts for the scanning strategy of the instrument as well as the combination of different detectors. We use this method to propagate errors through to the CMB angular power spectra in the particular case of Planck-HFI, and to derive constraints on polarization parameters. We show that in order to limit the systematic error to 10% of the cosmic variance of the $E$-mode power spectrum, uncertainties in gain, polarization efficiency and detector orientation must be below 0.15%, 0.3% and 1° respectively. Pre-launch ground measurements reported in this paper already fulfill these requirements.

astro-ph.CO↗

arXiv2009

Reconstruction of the CMB lensing for Planck

We prepare real-life Cosmic Microwave Background (CMB) lensing extraction with the forthcoming Planck satellite data, by studying two systematic effects related to the foregrounds contamination: the impact of foreground residuals after a component separation on the lensed CMB map, and of removing a large contaminated region of the sky. We first use the Generalized Morphological Component Analysis (GMCA) method to perform a component separation within a simplified framework which allows a high statistics Monte-Carlo study. For the second systematic, we apply a realistic mask on the temperature maps and then, restore them using a recent inpainting technique on the sphere. We investigate the reconstruction of the CMB lensing from the resultant maps using a quadratic estimator in the flat sky limit and on the full sphere. We find that the foreground residuals from the GMCA method does not alter significantly the lensed signal, nor does the mask corrected with the inpainting method, even in the presence of point sources residuals.

astro-ph.CO↗

arXiv2008

Generating long streams of $1/f^alpha$ noise

We review existing methods for generating long streams of 1/f^alpha noise ($0<α\le 2$) focusing on the digital filtering of white noise. We detail the formalism to conceive an efficient random number generator (white outside some bounds) in order to generate very long streams of noise without an exhaustive computer memory load. For $α=2$ it is shown why the process is equivalent to a random-walk and can be obtained simply by a first order filtering of white noise. As soon as $α<2$ the problem becomes non linear and we show why the exact digital filtering method becomes inefficient. Instead, we work out the formalism of using several 1/f^2 filters spaced logarithmically, to approximate the spectrum at the percent level. Finally, from work on logistic maps, we give hints on how to design generators with $α>2$. The software is available from http://planck.lal.in2p3.fr/article.php3?id\_article=8

astro-ph↗

arXiv2005

The CMB temperature power spectrum from an improved analysis of the Archeops data

We present improved results on the measurement of the angular power spectrum of the Cosmic Microwave Background (CMB) temperature anisotropies using the data from the last Archeops flight. This refined analysis is obtained by using the 6 most sensitive photometric pixels in the CMB bands centered at 143 and 217 GHz and 20% of the sky, mostly clear of foregrounds. Using two different cross-correlation methods, we obtain very similar results for the angular power spectrum. Consistency checks are performed to test the robustness of these results paying particular attention to the foreground contamination level which remains well below the statistical uncertainties. The multipole range from l=10 to l=700 is covered with 25 bins, confirming strong evidence for a plateau at large angular scales (the Sachs-Wolfe plateau) followed by two acoustic peaks centered around l=220 and l=550 respectively. These data provide an independent confirmation, obtained at different frequencies, of the WMAP first year results.

astro-ph↗

arXiv2005

Temperature and polarization angular power spectra of Galactic dust radiation at 353 GHz as measured by Archeops

We present the first measurement of temperature and polarization angular power spectra of the diffuse emission of Galactic dust at 353 GHz as seen by Archeops on 20% of the sky. The temperature angular power spectrum is compatible with that provided by the extrapolation to 353 GHz of IRAS and DIRBE maps using \cite{fds} model number 8. For Galactic latitudes $|b| \geq 5$ deg we report a 4 sigma detection of large scale ($3\leq \ell \leq 8$) temperature-polarization cross-correlation $(\ell+1)C_\ell^{TE}/2π= 76\pm 21 μ\rm{K_{RJ}}^2$ and set upper limits to the $E$ and $B$ modes at $11 μ\rm{K_{RJ}}^2$. For Galactic latitudes $|b| \geq 10$ deg, on the same angular scales, we report a 2 sigma detection of temperature-polarization cross-correlation $(\ell+1)C_\ell^{TE}/2π= 24\pm 13 μ\rm{K_{RJ}}^2$. These results are then extrapolated to 100 GHz to estimate the contamination in CMB measurements by polarized diffuse Galactic dust emission. The $TE$ signal is then $1.7\pm0.5$ and $0.5\pm0.3 μ\rm{K^2_{CMB}}$ for $|b| \geq 5$ and 10 deg. respectively. The upper limit on $E$ and $B$ becomes $0.2 μ\rm{K^2_{CMB}} (2σ)$. If polarized dust emission at higher Galactic latitude cuts is similar to the one we report here, then dust polarized radiation will be a major foreground for determining the polarization power spectra of the CMB at high frequencies above 100 GHz.

astro-ph↗

arXiv2003

Generic description of CMB power spectra

Taking advantage of the smoothness of CMB Cl power spectra, we derive a simple and model-independent parameterization of their measurement. It allows to describe completely the spectrum, ie. provide an estimate of the value and the error for any real l point at the percent level, down to low l multipole. We provide this parameterization for WMAP first year data and show that the spectrum is consistent with the smoothness hypothesis. We also show how such a parameterization allows to retrieve the Cl spectra from the measurement of Fourier rings on the sky (Gamma(m)) or from the angular correlation function (c(theta))

astro-ph↗

arXiv2003

About the connection between the $C_{\ell}$ power spectrum of the Cosmic Microwave Background and the $Γ_{m}$ Fourier spectrum of rings on the sky

In this article we present and study a scaling law of the $mΓ_m$ CMB Fourier spectrum on rings which allows us (i) to combine spectra corresponding to different colatitude angles (e.g. several detectors at the focal plane of a telescope), and (ii) to recover the $C_l$ power spectrum once the $Γ_m$ coefficients have been measured. This recovery is performed numerically below the 1% level for colatitudes $Θ> 80^\circ$ degrees. In addition, taking advantage of the smoothness of the $C_l$ and of the $Γ_m$, we provide analytical expressions which allow to recover one of the spectrum at the 1% level, the other one being known.

astro-ph↗

arXiv1999

Overall determination of the CKM matrix

We discuss the problem of theoretical uncertainties in the combination of observables related to the CKM matrix elements and propose a statistically sensible method for combining them. The overall fit is performed on present data, and constraints on the matrix elements are presented as well as on fB*sqrt(Bb). We then explore the implications of recent measurements and developments: jpsi-KS CP asymmetry, epsilon_prime/epsilon and B -> K pi branching fractions. Finally, we extract from the overall fit the Standard Model expectations for the rare kaon decays K -> pi nu anti-nu.

hep-ph↗

arXiv1998

CP violation with BaBar

The BABAR experiment is a new generation detector located at the SLAC B factory PEP-II ring which should start taking data at the end of 1999. Its main goal is the study of CP violation in the B0-B0b system. After explaining the nature of this CP violation, I review the scientific program for achieving this study in many different modes, in the light of the recent developments obtained both on the experimental and theoretical side. Implications for the Standard Model are then discussed.

hep-ph↗