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F. Touze

Publications and source records attributed to F. Touze.

2 recordsLinked to original sources

Iterative destriping and photometric calibration for Planck-HFI, polarized, multi-detector map-making

We present an iterative scheme designed to recover calibrated I, Q, and U maps from Planck-HFI data using the orbital dipole due to the satellite motion with respect to the Solar System frame. It combines a map reconstruction, based on a destriping technique, juxtaposed with an absolute calibration algorithm. We evaluate systematic and statistical uncertainties incurred during both these steps with the help of realistic, Planck-like simulations containing CMB, foreground components and instrumental noise, and assess the accuracy of the sky map reconstruction by considering the maps of the residuals and their spectra. In particular, we discuss destriping residuals for polarization sensitive detectors similar to those of Planck-HFI under different noise hypotheses and show that these residuals are negligible (for intensity maps) or smaller than the white noise level (for Q and U Stokes maps), for l > 50. We also demonstrate that the combined level of residuals of this scheme remains comparable to those of the destriping-only case except at very low l where residuals from the calibration appear. For all the considered noise hypotheses, the relative calibration precision is on the order of a few 10e-4, with a systematic bias of the same order of magnitude.

astro-ph.CO

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