Showing papers by "Alexandre Amblard published in 2003"
Cardiff University1, University of Paris2, University of Paris-Sud3, University of Toulouse4, California Institute of Technology5, Jet Propulsion Laboratory6, Institut d'Astrophysique de Paris7, Sapienza University of Rome8, University of Oxford9, University of Grenoble10, University of Minnesota11, Maynooth University12, Landau Institute for Theoretical Physics13, DSM14
TL;DR: In this paper, the cosmological constraints that Archeops places on adiabatic cold dark matter models with passive power-law initial fluctuations were analyzed, and the spectral index n was measured to be 1.04 (+0.10, 0.12) when the optical depth to reionization, tau, is allowed to vary as a free parameter, and 0.96 (+ 0.03,0.04) when tau is fixed to zero, both in good agreement with inflation.
Abstract: We analyze the cosmological constraints that Archeops places on adiabatic cold dark matter models with passive power-law initial fluctuations. Because its angular power spectrum has small bins in l and large l coverage down to COBE scales, Archeops provides a precise determination of the first acoustic peak in terms of position at multipole l_peak=220 +- 6, height and width. An analysis of Archeops data in combination with other CMB datasets constrains the baryon content of the Universe, Omega(b)h^2 = 0.022 (+0.003,-0.004), compatible with Big-Bang nucleosynthesis and with a similar accuracy. Using cosmological priors obtainedfrom recent non-CMB data leads to yet tighter constraints on the total density, e.g. Omega(tot)=1.00 (+0.03,-0.02) using the HST determination of the Hubble constant. An excellent absolute calibration consistency is found between Archeops and other CMB experiments, as well as with the previously quoted best fit model.The spectral index n is measured to be 1.04 (+0.10,-0.12) when the optical depth to reionization, tau, is allowed to vary as a free parameter, and 0.96 (+0.03,-0.04) when tau is fixed to zero, both in good agreement with inflation.
228 citations
Cardiff University1, University of Paris2, University of Paris-Sud3, University of Toulouse4, California Institute of Technology5, Institut d'Astrophysique de Paris6, Sapienza University of Rome7, University of Oxford8, University of Grenoble9, University of Minnesota10, Maynooth University11, Landau Institute for Theoretical Physics12, DSM13
TL;DR: In this paper, the angular power spectrum of the cosmic microwave background anisotropy in 16 bins over the multipole range l=15-350 was determined by the Archeops experiment.
Abstract: We present a determination by the Archeops experiment of the angular power spectrum of the cosmic microwave background anisotropy in 16 bins over the multipole range l=15-350. Archeops was conceived as a precursor of the Planck HFI instrument by using the same optical design and the same technology for the detectors and their cooling. Archeops is a balloon-borne instrument consisting of a 1.5 m aperture diameter telescope and an array of 21 photometers maintained at ~100 mK that are operating in 4 frequency bands centered at 143, 217, 353 and 545 GHz. The data were taken during the Arctic night of February 7, 2002 after the instrument was launched by CNES from Esrange base (Sweden). The entire data cover ~ 30% of the sky.This first analysis was obtained with a small subset of the dataset using the most sensitive photometer in each CMB band (143 and 217 GHz) and 12.6% of the sky at galactic latitudes above 30 degrees where the foreground contamination is measured to be negligible. The large sky coverage and medium resolution (better than 15 arcminutes) provide for the first time a high signal-to-noise ratio determination of the power spectrum over angular scales that include both the first acoustic peak and scales probed by COBE/DMR. With a binning of Delta(l)=7 to 25 the error bars are dominated by sample variance for l below 200. A companion paper details the cosmological implications.
206 citations
TL;DR: In this paper, a Monte-Carlo simulation is used to estimate the noise power spectrum in the time domain for CMB experiments, the power spectrum is extracted from the time ordered data avoiding the contamination coming from sky signal and accounting the pixellisation of the signal and the projection of the noise when making intermediate sky projections.
Abstract: We present a method designed to estimate the noise power spectrum in the time domain for CMB experiments. The noise power spectrum is extracted from the time ordered data avoiding the contamination coming from sky signal and accounting the pixellisation of the signal and the projection of the noise when making intermediate sky projections. This method is simple to implement and relies on Monte-Carlo simulations, it runs on a simple desk computer. We also propose a trick for filtering data before making coadded maps in order to avoid ringing due to the presence of signal in the timelines. These algorithms were succesfully tested on Archeops data.
7 citations
Cardiff University1, University of California, Berkeley2, University of Paris-Sud3, University of Paris4, Collège de France5, University of Toulouse6, European Space Research and Technology Centre7, California Institute of Technology8, Jet Propulsion Laboratory9, Institut d'Astrophysique de Paris10, Sapienza University of Rome11, Princeton University12, University of Oxford13, University of Minnesota14, Louisiana Public Service Commission15, Maynooth University16, Landau Institute for Theoretical Physics17, Space Research Institute18
TL;DR: The first determination of the Galactic polarized emission at 353 GHz by Archeops was made in 2002 as discussed by the authors, where the data were taken during the Arctic night of February 7, 2002 after the balloon-borne instrument was launched by CNES from the Swedish Esrange base near Kiruna.
Abstract: We present the first determination of the Galactic polarized emission at 353 GHz by Archeops. The data were taken during the Arctic night of February 7, 2002 after the balloon--borne instrument was launched by CNES from the Swedish Esrange base near Kiruna. In addition to the 143 GHz and 217 GHz frequency bands dedicated to CMB studies, Archeops had one 545 GHz and six 353 GHz bolometers mounted in three polarization sensitive pairs that were used for Galactic foreground studies. We present maps of the I, Q, U Stokes parameters over 17% of the sky and with a 13 arcmin resolution at 353 GHz (850 microns). They show a significant Galactic large scale polarized emission coherent on the longitude ranges [100, 120] and [180, 200] deg. with a degree of polarization at the level of 4-5%, in agreement with expectations from starlight polarization measurements. Some regions in the Galactic plane (Gem OB1, Cassiopeia) show an even stronger degree of polarization in the range 10-20%. Those findings provide strong evidence for a powerful grain alignment mechanism throughout the interstellar medium and a coherent magnetic field coplanar to the Galactic plane. This magnetic field pervades even some dense clouds. Extrapolated to high Galactic latitude, these results indicate that interstellar dust polarized emission is the major foreground for PLANCK-HFI CMB polarization measurement.
4 citations