Searcharxiv⌕ Search

arXiv subjects

P. de Bernardis

Publications and source records attributed to P. de Bernardis.

At least 289 records · Page 16Linked to original sources
arXiv2003

Measuring CMB Polarization with BOOMERANG

BOOMERANG is a balloon-borne telescope designed for long duration (LDB) flights around Antarctica. The second LDB Flight of BOOMERANG took place in January 2003. The primary goal of this flight was to measure the polarization of the CMB. The receiver uses polarization sensitive bolometers at 145 GHz. Polarizing grids provide polarization sensitivity at 245 and 345 GHz. We describe the BOOMERANG telescope noting changes made for 2003 LDB flight, and discuss some of the issues involved in the measurement of polarization with bolometers. Lastly, we report on the 2003 flight and provide an estimate of the expected results.

astro-ph↗
arXiv2003

MAXIMA: A Balloon-Borne Cosmic Microwave Background Anisotropy Experiment

We describe the Millimeter wave Anisotropy eXperiment IMaging Array (MAXIMA), a balloon-borne experiment designed to measure the temperature anisotropy of the Cosmic Microwave Background (CMB) on angular scales of 10' to 5 degrees . MAXIMA mapped the CMB using 16 bolometric detectors in spectral bands centered at 150 GHz, 240 GHz, and 410 GHz, with 10' resolution at all frequencies. The combined receiver sensitivity to CMB anisotropy was ~40 microK/rt(sec). Systematic parasitic contributions were minimized by using four uncorrelated spatial modulations, thorough crosslinking, multiple independent CMB observations, heavily baffled optics, and strong spectral discrimination. Pointing reconstruction was accurate to 1', and absolute calibration was better than 4%. Two MAXIMA flights with more than 8.5 hours of CMB observations have mapped a total of 300 deg^2 of the sky in regions of negligible known foreground emission. MAXIMA results have been released in previous publications. MAXIMA maps, power spectra and correlation matrices are publicly available at http://cosmology.berkeley.edu/maxima

astro-ph↗
arXiv2003

First Detection of Polarization of the Submillimetre Diffuse Galactic Dust Emission by Archeops

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.

astro-ph↗
arXiv2003

Observations of Galactic and Extra-galactic Sources From the BOOMERANG and SEST Telescopes

We present millimeter-wave observations of three extra-galactic and six Galactic sources in the Southern sky. Observations were made at 90, 150, 240 and 400 GHz with resolutions of 18, 10, 14 and 12 arcmin respectively during the 1998 Antarctic long duration balloon flight of BOOMERANG. Observations were also made with the SEST telescope, at 90 and 150 GHz with resolutions of 57 and 35 arcsec respectively. These observations can be used for calibrations of Cosmic Microwave Background (CMB) experiments as well as an understanding of the physical processes of the sources.

astro-ph↗
arXiv2003

Cosmological constraints from Archeops

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.

astro-ph↗
arXiv2003

The Cosmic Microwave Background Anisotropy Power Spectrum measured by Archeops

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.

astro-ph↗
arXiv2003

The BaR-SPOrt Experiment

BaR-SPOrt (Balloon-borne Radiometers for Sky Polarisation Observations) is an experiment to measure the linearly polarized emission of sky patches at 32 and 90 GHz with sub-degree angular resolution. It is equipped with high sensitivity correlation polarimeters for simultaneous detection of both the U and Q stokes parameters of the incident radiation. On-axis telescope is used to observe angular scales where the expected polarization of the Cosmic Microwave Background (CMBP) peaks. This project shares most of the know-how and sophisticated technology developed for the SPOrt experiment onboard the International Space Station. The payload is designed to flight onboard long duration stratospheric balloons both in the Northern and Southern hemispheres where low foreground emission sky patches are accessible. Due to the weakness of the expected CMBP signal (in the range of microK), much care has been spent to optimize the instrument design with respect to the systematics generation, observing time efficiency and long term stability. In this contribution we present the instrument design, and first tests on some components of the 32 GHz radiometer.

astro-ph↗
arXiv2002

Improved Measurement of the Angular Power Spectrum of Temperature Anisotropy in the CMB from Two New Analyses of BOOMERANG Observations

We report the most complete analysis to date of observations of the Cosmic Microwave Background (CMB) obtained during the 1998 flight of BOOMERANG. We use two quite different methods to determine the angular power spectrum of the CMB in 20 bands centered at l = 50 to 1000, applying them to 50% more data than has previously been analyzed. The power spectra produced by the two methods are in good agreement with each other, and constitute the most sensitive measurements to date over the range 300 < l < 1000. The increased precision of the power spectrum yields more precise determinations of several cosmological parameters than previous analyses of BOOMERANG data. The results continue to support an inflationary paradigm for the origin of the universe, being well fit by a 13.5 Gyr old, flat universe composed of approximately 5% baryonic matter, 30% cold dark matter, and 65% dark energy, with a scale invariant initial density perturbations.

astro-ph↗
arXiv2002

Search for non-gaussian signals in the BOOMERanG maps: pixel-space analysis

We search the BOOMERanG maps of the anisotropy of the Cosmic Microwave Background (CMB) for deviations from gaussianity. In this paper we focus on analysis techniques in pixel-space, and compute skewness, kurtosis and Minkowski functionals for the BOOMERanG maps and for gaussian simulations of the CMB sky. We do not find any significant deviation from gaussianity in the high galactic latitude section of the 150 GHz map. We do find deviations from gaussianity at lower latitudes and at 410 GHz, and we ascribe them to Galactic dust contamination. Using non-gaussian simulations of instrumental systematic effects, of foregrounds, and of sample non-gaussian cosmological models, we set upper limits to the non-gaussian component of the temperature field in the BOOMERanG maps. For fluctuations distributed as a 1 DOF $χ^2$ mixed to the main gaussian component our upper limits are in the few % range.

astro-ph↗
arXiv2002

A measurement by BOOMERANG of multiple peaks in the angular power spectrum of the cosmic microwave background

This paper presents a measurement of the angular power spectrum of the Cosmic Microwave Background from l=75 to l=1025 (~10' to 5 degrees) from a combined analysis of four 150 GHz channels in the BOOMERANG experiment. The spectrum contains multiple peaks and minima, as predicted by standard adiabatic-inflationary models in which the primordial plasma undergoes acoustic oscillations. These results significantly constrain the values of Omega_tot, Omega_b h^2, Omega_c h^2 and n_s.

astro-ph↗
arXiv2002

The BOOMERanG experiment and the curvature of the Universe

We describe the BOOMERanG experiment and its main result, i.e. the measurement of the large scale curvature of the Universe. BOOMERanG is a balloon-borne microwave telescope with sensitive cryogenic detectors. BOOMERanG has measured the angular distribution of the Cosmic Microwave Background on $\sim 3%$ of the sky, with a resolution of $\sim 10$ arcmin and a sensitivity of $\sim 20 μK$ per pixel. The resulting image is dominated by hot and cold spots with rms fluctuations $\sim 80 μK$ and typical size of $\sim 1^o$. The detailed angular power spectrum of the image features three peaks and two dips at $\ell = (213^{+10}_{-13}), (541^{+20}_{-32}), (845^{+12}_{-25})$ and $\ell = (416^{+22}_{-12}), (750^{+20}_{-750})$, respectively. Such very characteristic spectrum can be explained assuming that the detected structures are the result of acoustic oscillations in the primeval plasma. In this framework, the measured pattern constrains the density parameter $Ω$ to be $0.85 < Ω< 1.1$ (95% confidence interval). Other cosmological parameters, like the spectral index of initial density fluctuations, the density parameter for baryons, dark matter and dark energy, are detected or constrained by the BOOMERanG measurements and by other recent CMB anisotropy experiments. When combined with other cosmological observations, these results depict a new, consistent, cosmological scenario.

astro-ph↗
arXiv2001

Constraints on Cosmological Parameters from MAXIMA-1

We set new constraints on a seven-dimensional space of cosmological parameters within the class of inflationary adiabatic models. We use the angular power spectrum of the cosmic microwave background measured over a wide range of \ell in the first flight of the MAXIMA balloon-borne experiment (MAXIMA-1) and the low \ell results from COBE/DMR. We find constraints on the total energy density of the universe, Ω=1.0^{+0.15}_{-0.30}, the physical density of baryons, Ω_{b}h^2=0.03 +/- 0.01, the physical density of cold dark matter, Ω_{cdm}h^2=0.2^{+0.2}_{-0.1}$, and the spectral index of primordial scalar fluctuations, n_s=1.08+/-0.1, all at the 95% confidence level. By combining our results with measurements of high-redshift supernovae we constrain the value of the cosmological constant and the fractional amount of pressureless matter in the universe to 0.45<Ω_Λ<0.75 and 0.25<Ω_{m}<0.50, at the 95% confidence level. Our results are consistent with a flat universe and the shape parameter deduced from large scale structure, and in marginal agreement with the baryon density from big bang nucleosynthesis.

astro-ph↗
arXiv2001

Multiple Peaks in the Angular Power Spectrum of the Cosmic Microwave Background: Significance and Consequences for Cosmology

Three peaks and two dips have been detected in the power spectrum of the cosmic microwave background from the BOOMERANG experiment, at $\ell \sim 210, 540, 840$ and $\ell \sim 420, 750$, respectively. Using model-independent analyses, we find that all five features are statistically significant and we measure their location and amplitude. These are consistent with the adiabatic inflationary model. We also calculate the mean and variance of the peak and dip locations and amplitudes in a large 7-dimensional parameter space of such models, which gives good agreement with the model-independent estimates, and forecast where the next few peaks and dips should be found if the basic paradigm is correct. We test the robustness of our results by comparing Bayesian marginalization techniques on this space with likelihood maximization techniques applied to a second 7-dimensional cosmological parameter space, using an independent computational pipeline, and find excellent agreement: $Ω_{\rm tot} = 1.02^{+0.06}_{-0.05}$ {\it vs.} $1.04 \pm 0.05$, $Ω_b h^2 = 0.022^{+0.004}_{-0.003}$ {\it vs.} $0.019^{+0.005}_{-0.004}$, and $n_s = 0.96^{+0.10}_{-0.09}$ {\it vs.} $0.90 \pm 0.08$. The deviation in primordial spectral index $n_s$ is a consequence of the strong correlation with the optical depth.

astro-ph↗
arXiv2001

The BOOMERANG North America Instrument: a balloon-borne bolometric radiometer optimized for measurements of cosmic background radiation anisotropies from 0.3 to 4 degrees

We describe the BOOMERANG North America (BNA) instrument, a balloon-borne bolometric radiometer designed to map the Cosmic Microwave Background (CMB) radiation with 0.3 deg resolution over a significant portion of the sky. This receiver employs new technologies in bolometers, readout electronics, millimeter-wave optics and filters, cryogenics, scan and attitude reconstruction. All these subsystems are described in detail in this paper. The system has been fully calibrated in flight using a variety of techniques which are described and compared. It has been able to obtain a measurement of the first peak in the CMB angular power spectrum in a single balloon flight, few hours long, and was a prototype of the BOOMERANG Long Duration Balloon (BLDB) experiment.

astro-ph↗
arXiv2001

Cosmology from Maxima-1, Boomerang and COBE/DMR CMB Observations

Recent results from BOOMERANG-98 and MAXIMA-1, taken together with COBE-DMR, provide consistent and high signal-to-noise measurements of the CMB power spectrum at spherical harmonic multipole bands over $2<\ell\lta800$. Analysis of the combined data yields 68% (95%) confidence limits on the total density, $Ω_{\rm {tot}}\simeq 1.11 \pm 0.07 (^{+0.13}_{-0.12})$, the baryon density, $Ω_b h^2\simeq 0.032^{+0.005}_{-0.004} (^{+0.009}_{-0.008})$, and the scalar spectral tilt, $n_s\simeq1.01^{+0.09}_{-0.07} (^{+0.17}_{-0.14})$. These data are consistent with inflationary initial conditions for structure formation. Taken together with other cosmological observations, they imply the existence of both non-baryonic dark matter and dark energy in the universe.

astro-ph↗
arXiv2001

High latitude Galactic dust emission in the BOOMERanG maps

We present mm-wave observations obtained by the BOOMERanG experiment of Galactic emission at intermediate and high (b < -20 deg) Galactic latitudes. We find that this emission is well correlated with extrapolation of the IRAS-DIRBE maps, and is spectrally consistent with thermal emission from interstellar dust (ISD). The ISD brightness in the 410 GHz map has an angular power spectrum c_l = A l^{-beta} with 2 < beta < 3. At 150 GHz and at multipoles ell \sim 200 the angular power spectrum of the IRAS-correlated dust signal is estimated to be l(l+1)c_l/2 pi = (3.7 \pm 2.9) uK^2. This is negligible with respect to the CMB signal measured by the same experiment l(l+1)c_l/2 pi = (4700 \pm 540) uK^2. For the uncorrelated dust signal we set an upper limit to the contribution to the CMB power at 150GHz and l \sim 200 of l(l+1)c_l/2 pi < 3 uK^2 at 95% C.L. .

astro-ph↗
arXiv2000

Detection of anisotropy in the Cosmic Microwave Background at horizon and sub-horizon scales with the BOOMERanG experiment

BOOMERanG has recently resolved structures on the last scattering surface at redshift $\sim$ 1100 with high signal to noise ratio. We review the technical advances which made this possible, and we focus on the current results for maps and power spectra, with special attention to the determination of the total mass-energy density in the Universe and of other cosmological parameters.

astro-ph↗