Showing papers by "D. Santos published in 2008"

Constraints on the non-linear coupling parameter fnl with the Archeops data

Abstract: Aims. We present a Gaussianity analysis of the Archeops Cosmic Microwave Background (CMB) temperature anisotropies data maps at high resolution to constrain the non-linear coupling parameter fnl characterising well motivated non-Gaussian CMB models. We used the data collected by the most sensitive Archeops bolometer at 143 GHz to perform this analysis. For this purpose, the instrumental noise was carefully characterised for this bolometer, and for another Archeops bolometer at 143 GHz used for comparison. Angular scales from 27 arcmin to 1.8 degrees and a large fraction of the sky, 21%, covering both hemispheres (avoiding pixels with Galactic latitude |b| < 15 degrees) were considered. Methods. The three Minkowski functionals on the sphere evaluated at different thresholds were used to construct a � 2 statistics for both the Gaussian as well as for the non-Gaussian CMB models. The Archeops maps were produced with the Mirage optimal map-making procedure from processed time ordered data. The analysis is based on simulations of signal (Gaussian and non-Gaussian fnl CMB models) and noise which were processed in the time domain using the Archeops pipeline and projected on the sky using the Mirage optimal map-making procedure. Results. The Archeops data were found to be compatible with Gaussianity after removal of highly noisy pixels at high resolution. The non-linear coupling parameter was constrained to fnl = 70 +590 400 at 68% CL and fnl = 70 +1075 920 at 95% CL, for realistic non-Gaussian CMB simulations.

Constraints on the non-linear coupling parameter fnl with the Archeops data

Abstract: We present a Gaussianity analysis of the Archeops Cosmic Microwave Background (CMB) temperature anisotropy data maps at high resolution to constrain the non-linear coupling parameter fnl characterising well motivated non-Gaussian CMB models. We used the data collected by the most sensitive Archeops bolometer at 143 GHz. The instrumental noise was carefully characterised for this bolometer, and for another Archeops bolometer at 143 GHz used for comparison. Angular scales from 27 arcmin to 1.8 degrees and a large fraction of the sky, 21 %, covering both hemispheres (avoiding pixels with Galactic latitude |b| < 15 degrees) were considered. The three Minkowski functionals on the sphere evaluated at different thresholds were used to construct a chi-squared statistics for both the Gaussian and the non-Gaussian CMB models. The Archeops maps were produced with the Mirage optimal map-making procedure from processed time ordered data. The analysis is based on simulations of signal (Gaussian and non-Gaussian fnl CMB models) and noise which were processed in the time domain using the Archeops pipeline and projected on the sky using the Mirage optimal map-making procedure. The Archeops data were found to be compatible with Gaussianity after removal of highly noisy pixels at high resolution. The non-linear coupling parameter was constrained to -400 < fnl < 590 at 68% CL and -920 < fnl < 1075 at 95% CL, for realistic non-Gaussian CMB simulations.

Development of Large Bolometer Arrays for Submillimeter and Millimeter Astronomy

Abstract: Access to new microelectronics facilities allows the development of large bolometer arrays for astronomy. The expected sensitivity increase is the key for the next generation of cameras at the focal plane of submillimeter and millimeter telescopes. We present here the research led in France in this domain.