Aims. Archeops is a balloon–borne experiment widely inspired by the Planck satellite and by its High Frequency Instrument (HFI). It is mainly dedicated to measure the Cosmic Microwave Background (CMB) temperature anisotropies at high angular resolution (∼ 12 arcminutes) over a large fraction of the sky (around 30 %) in the millimetre and submillimetre range at 143, 217, 353 and 545 GHz. Further, the Archeops 353 GHz channel consists of three pairs of polarized sensitive bolometers designed to detect the polarized diffuse emission of Galactic dust.
Methods. We present in this paper the update of the instrumental setup as well as the inflight performance for the last Archeops flight campaign in February 2002 from Kiruna (Sweden). We also describe the processing and analysis of the Archeops time ordered data for that campaign which lead to the measurement of the CMB anisotropies power spectrum in the multipole range l = 10 − 700 (Benoît et al. 2003a, Tristram et al. 2005) and to the first measurement of the dust polarized emission at large angular scales and its polarized power spectra in the multipole range l = 3 − 70 (Benoît et al. 2004, Ponthieu et al. 2005).
Results. We present maps of 30 % of the sky of the Galactic emission, including the Galactic plane, in the four Archeops channels at 143, 217, 353 and 545 GHz and maps of the CMB anisotropies at 143 and 217 GHz. These are the first ever available sub–degree resolution maps in the millimetre and submillimetre range of the large angular-scales Galactic dust diffuse emission and CMB temperature anisotropies respectively.

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| >= 5 deg we report a 4 sigma detection of large scale (3 <= l  <= 8) temperature-polarization cross-correlation (l+1)C_l^TE/2pi = 76 +/- 21 μK_RJ² and set upper limits to the E and B modes at 11 μK_RJ². For Galactic latitudes |b| <= 10 deg, on the same angular scales, we report a 2 sigma detection of temperature-polarization cross-correlation (l+1)C__l^TE/2pi = 24 +/- 13 μK_RJ². 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 +/- 0.5 and 0.5 +/- 0.3 μK_CMB2 for |b| <= 5 and 10 deg. respectively. The upper limit on E and B becomes 0.2 μK_CMB2 (2 sigmas). 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.

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.

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.

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.

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.

Archeops is a balloon-borne instrument dedicated to measuring cosmic microwave background (CMB) temperature anisotropies at high angular resolution (8') over a large fraction (25%) of the sky in the millimetre domain. Based on Planck high frequency instrument technology, cooled bolometers (0.1 K) scan the sky in total power mode with large circles at constant elevation. During the course of a 24-h Arctic-night balloon flight, Archeops will observe a complete annulus on the sky in four frequency bands centered at 143, 217, 353 and 545 GHz with an expected sensitivity to CMB fluctuations of 100 μK for each of the 90 thousand 20' average pixels. We describe the instrument and its performance obtained during a test flight from Trapani (Sicily) to Spain in July 1999.

We have combined infrared data with HI , H2 , and HII surveys to spatially decompose the observed dust emission into components associated with different phases of the gas. An inversion technique is applied. For the decomposition, we use the IRAS 60 and 100 μm bands, the DIRBE 140 and 240 μm bands, as well as Archeops 850 and 2096 μm wavelengths. In addition, we apply the decomposition to all five WMAP bands. We obtain longitude and latitude profiles for each wavelength and for each gas component in carefully selected Galactic radius bins. We also derive emissivity coefficients for dust in atomic, molecular, and ionized gas in each of the bins. The HI emissivity appears to decrease with increasing Galactic radius indicating that dust associated with atomic gas is heated by the ambient interstellar radiation field (ISRF). By contrast, we find evidence that dust mixed with molecular clouds is significantly heated by O/B stars still embedded in their progenitor clouds. By assuming a modified blackbody with emissivity law λ−1.5 , we also derive the radial distribution of temperature for each phase of the gas. All of the WMAP bands except W appear to be dominated by emission from something other than normal dust, most likely a mixture of thermal bremstrahlung from diffuse ionized gas, synchrotron emission, and spinning dust. Furthermore, we find indications of an emissivity excess at long wavelengths (λ ≥ 850 μm) in the outer Galaxy (R > 8.9 kpc). This suggests either the existence of a very cold dust component in the outer Galaxy or a temperature dependence of the spectral emissivity index. Finally, it is shown that ∼80% of the total FIR luminosity is produced by dust associated with atomic hydrogen, in agreement with earlier findings. The work presented here has been carried out as part of the development of analysis tools for the planned European Space Agency (ESA) Planck mission.

We present an alternative analysis of CMB time-ordered data (TOD) using a wavelet-based representation of the data time-frequency plane. We demonstrate that the wavelet transform decorrelates 1/ f -type Gaussian stationary noise and permits a simple and functional description of locally stationary processes. In particular, this makes it possible to generalize the classical algorithms of map making and CMB power-spectrum estimation to the case of locally stationary 1/ f type noise. As an example, we present a wavelet-based algorithm for the destriping of CMB-like maps. In addition, we describe a wavelet-based analysis of the Archeops data including time-frequency visualization, wavelet destriping, and filtering of the TOD. These filtered data were used to produce polarized maps of Galactic dust diffuseemission. Finally, we describe the modeling of the non-stationarity on the Archeops noise for estimating the CMB power spectrum.

We present XSPECT, a method to obtain estimates of the angular power spectrum of the cosmic microwave background (CMB) temperature anisotropies including analytical error bars developed for the Archeops experiment. Cross-power spectra are computed from a set of maps and each of them is in itself an unbiased estimate of the power spectrum as long as the detector noises are uncorrelated. Then, the cross-power spectra are combined into a final temperature power spectrum with error bars analytically derived from the cross-correlation matrix. This method presents three main useful properties: (1) no estimation of the noise power spectrum is needed; (2) complex weighting schemes including sky covering and map noise properties can be easily taken into account, and corrected for, for each input map; and (3) error bars are quickly computed analytically from the data themselves with no Monte Carlo simulations involved. XSPECT also permits the study of common fluctuations between maps from different sky surveys such as CMB, Sunyaev-Zel'dovich effect or mass fluctuations from weak lensing observations.

A major goal of CMB experiments is to obtain highly sensitive CMB maps in order to extract Spherical Harmonic Power Spectrum (SHPS) and cosmological parameters with unprecedented accuracy. We present a new map-making code (Mirage), based on a two-phase iterative algorithm, involving low frequency drift treatment, Butterworth high-pass filtering and conjugate gradient method. This work was strongly motivated by Archeops CMB experiment data analysis. We believe that Archeops was a good test bench for the future Planck Surveyor data analysis, and Mirage was designed in order to be used for Planck data processing with minimal work. A strong feature of Mirage is that it handles experimental problems in data, such as holes in data stream, bright sources, and galaxy side effects, without jeopardising speed. The other advantage is its processing speed, allowing to run Monte Carlo simulations of Archeops data processing on a single processor workstation overnight. Algorithms are explained. Systematic effects on SHPS are investigated on various simulated data, including typical Archeops observational systematics.

We describe a fast and accurate method to perform the convolution of a sky map with a general asymmetric main beam along any given scanning strategy. The method is based on the decomposition of the beam as a sum of circular functions, here Gaussians. It can be easily implemented and is much faster than pixel-by-pixel convolution. In addition, ASYMFAST can be used to estimate the effective circularized beam transfer functions of cosmic microwave background instruments with nonsymmetric main beam. This is shown using realistic simulations and by comparison to analytical approximations which are available for Gaussian elliptical beams. Finally, the application of this technique to ARCHEOPS data is also described. Although developed within the framework of cosmic microwave background observations, our method can be applied to other areas of astrophysics.

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.

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

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. The three Minkowski functionals on the sphere evaluated at different thresholds were used to construct a chi-squared 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. 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.

Archeops is a balloon-borne experiment, mainly designed to measure the Cosmic Microwave Background (CMB) temperature anisotropies at high angular resolution (~ 12 arcminutes). By-products of the mission are shallow sensitivity maps over a large fraction of the sky (about 30 %) in the millimetre and submillimetre range at 143, 217, 353 and 545 GHz. From these maps, we produce a catalog of bright submillimetre point sources. We present in this paper the processing and analysis of the Archeops point sources. Redundancy across detectors is the key factor allowing to sort out glitches from genuine point sources in the 20 independent maps. We look at the properties of the most reliable point sources, totalling 304. Fluxes range from 1 to 10,000 Jy (at the frequencies covering 143 to 545 GHz). All sources are either planets (2) or of galactic origin. Longitude range is from 75 to 198 degrees. Some of the sources are associated with well-known Lynds Nebulae and HII compact regions in the galactic plane. A large fraction of the sources have an IRAS counterpart. Except for Jupiter, Saturn, the Crab and CasA, all sources show a dust-emission-like modified blackbody emission spectrum. Temperatures cover a range from 7 to 27 K. For the coldest sources (T < 10 K), a steep nu^beta emissivity law is found with a surprising beta ~ 3 to 4. An inverse relationship between T and beta is observed. The number density of sources at 353 GHz with flux brighter than 100 Jy is of the order of 1 per degree of Galactic longitude. These sources will provide a strong check for the calibration of the Planck HFI focal plane geometry in complement to planets. These very cold sources observed by Archeops should be prime targets for mapping observations by the Akari and Herschel space missions and ground--based observatories.

A Gaussianity analysis using a goodness-of-fit test and the Minkowski functionals on the sphere has been performed to study the measured Archeops Cosmic Microwave Background (CMB) temperature anisotropy data for a 143 GHz Archeops bolometer. We consider large angular scales, greater than 1.8 degrees, and a large fraction of the North Galactic hemisphere, around 16%, with a galactic latitude b > 15 degrees. The considered goodness-of-fit test, first proposed by Rayner & Best (1989), has been applied to the data after a signal-to-noise decomposition. The three Minkowski functionals on the sphere have been used to construct a chi-square statistic using different thresholds. The first method has been calibrated using simulations of Archeops data containing the CMB signal and instrumental noise in order to check its asymptotic convergence. Two kind of maps produced with two different map-making techniques (coaddition and Mirage) have been analysed. Archeops maps for both Mirage and coaddition map-making, have been found to be compatible with Gaussianity. From these results we can exclude a dust and atmospheric contamination larger than 7.8% (90% CL). Also the non-linear coupling parameter f_{nl} can be constrained to be -800 < f_{nl} < 1100 at the 95% CL and on angular scales of 1.8 degrees. For comparison, the same method has been applied to data from the NASA WMAP satellite in the same region of sky. The 1-year and 3-year releases have been used. Results are compatible with those obtained with Archeops, implying in particular an upper limit for f_{nl} on degree angular scales.

In this paper, we present a joint cross-correlation analysis of the Archeops CMB maps at 143 and 217 GHz and the WMAP CMB maps at 41, 61 and 94 GHz with sky templates of projected galaxy density constructed from the 2MASS Extended Source catalog. These templates have been divided in patches sorted in decreasing galaxy density with a fixed number of pixels (we considered patches having 32, 64 and 128 pixels) and the cross correlation has been performed independently for each of these patches. We find that the densest patch shows a strong temperature decrement in the Q, V, W bands of WMAP and in the 143 GHz channel of Archeops, but not in the 217 GHz channel. Furthermore, we find that the spectral behavior of the amplitude of this decrement is compatible with that expected for the non-relativistic thermal Sunyaev-Zel'dovich effect, and is incompatible (at 4.5 sigma level) with the null hypothesis of having only CMB, noise and a dust component (nu^2) in those pixels. We find that the first 32-pixel sized patch samples the cores of 11 known massive nearby galaxy clusters. Under the assumption that the decrement found in this patch is due entirely to the thermal Sunyaev-Zel'dovich effect, we obtain an average comptonization parameter for those sources of y = (0.41 +- 0.08) x 10^(-4) at 13 arcmin angular scales. This value is compatible at 1 sigma with the expectation, y = 0.49 x 10^(-4), from a model of the cluster flux number counts based on the standard Lambda-CDM cosmology. The observed value of y is slightly diluted when computed for the first patch of 64 and 128 pixels, presumably due to the inclusion of less massive clusters, and the dilution factor inferred is also compatible with the quoted model.

We present cosmological parameter constraints on flat cosmologies dominated by dark energy using various cosmological data including the recent Archeops angular power spectrum measurements. A likelihood analysis of the existing Cosmic Microwave Background data shows that in the absence of further prior, dark energy is not required. This comes from the fact that degeneracies exist among the various cosmological parameters constrained by the Cosmic Microwave Background. We found that there is a degeneracy in a combination of the Hubble parameter H₀ and of the dark energy equation of state parameter w_Q, but that w_Q is not correlated with the primordial index n of scalar fluctuations and the baryon content Omega_b h². The preferred primordial index is n = 0.95 +/- 0.05 (68%) and baryon content Omega_b h² = 0.021 +/- 0.003. Adding constraints on the amplitude of matter fluctuations on small scales, sigma₈, obtained from clusters abundance or weak lensing data may allow degenaracies to be broken, although present-day systematic uncertainties do not allow for firm conclusions as yet. Further addition of the Hubble Space Telescope measurements of the local distance scale and of the high redshift supernovae data allow one to obtain tight constraints. When these constraints are combined we find that the amount of dark energy is 0.7^+0.10_-0.07 (95% C.L.) and that its equation of state is very close to those of the vacuum: w_Q< -0.75 (> 95% C.L.). In no case do we find that quintessence is prefered over the classical cosmological constant, although robust data on sigma₈ might rapidly shed light on this important issue.