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The Boomerang experiment completed its final long duration balloon (LDB) flight over Antarctica in January 2003. The focal plane was upgraded to accommodate four sets of 145 GHz polarization sensitive bolometers (PSBs), identical to those to be flown on the Planck HFI instrument. Approximately, 195 hours of science observations were obtained during this flight, including 75 hours distributed over 1.84% of the sky and an additional 120 hours concentrated on a region covering 0.22% of the sky. We derive the angular power spectra of the cosmic microwave background (cmb) temperature and polarization anisotropies from these data. The temperature anisotropies are detected with high signal to noise on angular scales ranging from several degrees to ∼10 arcminutes. The curl-free (EE) component is detected at ∼4.8σ, and a two-sigma upper limit on the curl (BB) component of 8.6 μK2 is obtained on scales corresponding to ∼0.5°. Both the temperature and polarization anisotropies are found to be consistent with a concordance ΛCDM cosmology that is seeded by adiabatic density perturbations. In addition to the cmb observations, Boomerang03 surveyed a ∼300 square degree region centered on the Galactic plane. These observations represent the first light for polarization sensitive bolometers, which are currently operational in two South-Pole based polarimeters, as well as Planck HFI, at frequencies ranging from 100 to 350 GHz (3 mm to 850 μm).

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. .

A new generation of Cosmic Microwave Background Radiation (CMBR) experiments are currently providing the first precision measurements of fluctuations in the CMBR. These fluctuations hold information about all the fundamental cosmological parameters, and the experiments have already confirmed beyond reasonable doubt that the geometry of the universe is very close to being flat. The new CMBR experiments can also be used to probe particle physics beyond the standard model. For instance, data from the new Boomerang experiment yield an upper limit on the effective number of neutrinos present at recombination, N ν ≤ 13 (95% C.L.). This already puts significant constraints on many non-standard neutrino scenarios, such as the possible bulk neutrino modes expected in theories with large extra dimensions. The upcoming satellite experiments will improve the sensitivity of the CMBR by almost an order of magnitude and make the CMBR an excellent laboratory for precision particle physics.

We propose and implement a fast, universally applicable method for extracting the angular power spectrum from cosmic microwave background temperature maps by first estimating the correlation function . Our C y(v) procedure recovers the using (but potentially ) operations, where N is the number of pixels. This 2 C NN log N is in contrast with standard maximum likelihood techniques that require operations. Our method makes no 3 N special assumptions about the map, unlike present-day fast techniques that rely on symmetries of the underlying noise matrix, sky coverage, scanning strategy, and geometry. This makes analysis of megapixel maps without symmetries possible for the first time. The key element of our technique is the accurate multipole decomposition of . The error bars and cross-correlations are found by using a Monte Carlo approach. We applied our y(v) C technique to a large number of simulated maps with BOOMERanG (Balloon Observations Of Millimetric Radiation and Geophysics) sky coverage in 81,000 pixels. We used a diagonal noise matrix, with approximately the same amplitude as the BOOMERanG experiment. These studies demonstrate that our technique provides an unbiased estimator of the . Even though our method is approximate, the error bars obtained are nearly optimal, C and they converged only after a few tens of Monte Carlo realizations. Our method is directly applicable for the nondiagonal noise matrix. This and other generalizations, such as minimum variance weighting schemes, polarization, and higher order statistics, are also discussed. Subject headings: cosmic microwave background — cosmology: theory — methods: statistical On-line material: color figures

The BOOMERANG (Balloon Observations Of Millimetric Extragalactic Radiation aNd Geophysics) experiment is an international effort to measure the Cosmic Microwave Background (CMB) anisotropy on angular scales of 20' to 40 degrees, with unprecedented sensitivity, sky and spectral coverage. The telescope will be flown from Antarctica by NASA-NSBF with a long duration stratospheric balloon (7-14 days), and is presently scheduled for flight in 1995-1996. The experiment is designed to produce an image of the Cosmic Microwave Background with high sensitivity and large sky coverage. These data will tightly constrain the baryon density, the reionization history, and the formation of large-scale structure in the universe. BOOMERANG will test technologies and return science data that are essential to the design of a future space-borne mission to map CMB anisotropy.

We discuss instrumental and analytic methods that have been developed for the first generation of bolometric cosmic microwave background (CMB) polarimeters. The design, characterization, and analysis of data obtained using Polarization Sensitive Bolometers (PSBs) are described in detail. This is followed by a brief study of the effect of various polarization modulation techniques on the recovery of sky polarization from scanning polarimeter data. Having been successfully implemented on the sub-orbital Boomerang experiment, PSBs are currently operational in two terrestrial CMB polarization experiments (QUaD and the Robinson Telescope). We investigate two approaches to the analysis of data from these experiments, using realistic simulations of time ordered data to illustrate the impact of instrumental effects on the fidelity of the recovered polarization signal. We find that the analysis of difference time streams takes full advantage of the high degree of common mode rejection afforded by the PSB design. In addition to the observational efforts currently underway, this discussion is directly applicable to the PSBs that constitute the polarized capability of the Planck HFI instrument., 23 pages, 11 figures. for submission to A&A

Polarized diffuse emission observations at 2.3 GHz in a high Galactic latitude area are presented. The 2\degr X 2\degr field, centred in (\alpha=5^h,\delta=-49\degr), is located in the region observed by the BOOMERanG experiment. Our observations has been carried out with the Parkes Radio telescope and represent the highest frequency detection done to date in low emission areas. Because of a weaker Faraday rotation action, the high frequency allows an estimate of the Galactic synchrotron contamination of the Cosmic Microwave Background Polarization (CMBP) that is more reliable than that done at 1.4 GHz. We find that the angular power spectra of the E- and B-modes have slopes of \beta_E = -1.46 +/- 0.14 and \beta_B = -1.87 +/- 0.22, indicating a flattening with respect to 1.4 GHz. Extrapolated up to 32 GHz, the E-mode spectrum is about 3 orders of magnitude lower than that of the CMBP, allowing a clean detection even at this frequency. The best improvement concerns the B-mode, for which our single-dish observations provide the first estimate of the contamination on angular scales close to the CMBP peak (about 2 degrees). We find that the CMBP B-mode should be stronger than synchrotron contamination at 90 GHz for models with T/S > 0.01. This low level could move down to 60-70 GHz the optimal window for CMBP measures., Comment: 5 pages, 6 figures, accepted for publication in MNRAS Letters

We discuss the algorithmic information approach to the analysis of the observational data on the Universe. Kolmogorov complexity is proposed as a descriptor of the Cosmic Microwave Background (CMB) radiation maps. An algorithm of computation of the complexity is described, applied, first, to toy models and then, to the data of the Boomerang experiment. The sky maps obtained via the summing of two independent Boomerang channels reveal threshold independent behavior of the mean ellipticity of the anisotropies, thus indicating correlations present in the sky signal and possibly carrying crucial information on the curvature and the non-Friedmannian, i.e. accelerated expansion of the Universe. Similar effect has been detected for COBE-DMR 4 year maps. Finally, as another application of these concepts, we consider the possible link between the CMB properties, curvature of the Universe and arrows of time., Talk at XXII Solvay Conference on Physics "The Physics of Communication" (Delphi, November 24-29, 2001); the discussion included

Thermal emission from interstellar dust is a potential contaminant for sensitive measurements of Cosmic Microwave Background anisotropies. Here we analyze the mm-wave observations obtained by the BOOMERanG experiment at 90, 150, 240 and 410 GHz. Galactic emission has been detected at intermediate and high (b < -20°) Galactic latitudes, and is morphologically similar to the dust emission mapped by the IRAS satellite at 3000 GHz and by the DIRBE instrument on COBE at 1250 GHz. We show that the 410 GHz channel of BOOMERanG is a good monitor of dust emission, and that at 150 GHz the contamination is negligible with respect to the anisotropy of the cosmic microwave background (CMB) detected by the same instrument.

The BOOMERANG experiment provided the first high resolution map of the Cosmic Microwave Background (CMB) radiation. In this paper we summarize the main parts of the instrument, including bolometers, cryogenics, optics and pointing system. We show then how the instrument is designed to be robust to systematic effects.

Interstellar dust (ISD) emission is present in the mm-wave maps obtained by the BOOMERanG experiment at intermediate and high Galactic latitudes. We find that, while being sub-dominant at the lower frequencies (90, 150, 240 GHz), thermal emission from ISD is dominant at 410 GHz, and is well correlated with the IRAS map at 100 μm. We find also that the angular power spectrum of ISD fluctuations at 410 GHz is a power law, and its level is negligible with respect to the angular power spectrum of the Cosmic Microwave Background (CMB) at 90 and 150 GHz.

We describe the new BOOMERanG payload, which is being prepared for a new circum-antarctic flight, with the aim to detect the linear polarization of the Cosmic Microwave Background (CMB). In addition to polarization capabilities, obtained by means of special bolometers, the instrument has been improved in the attitude reconstruction system and in the calibration system.

In this paper we report a short description of the BOOMERANG experiment explaining his scientific goal and the technologies implied. We concentrate then on the analysis of the noise properties discussing in particular the scan synchronous noise. Finally we present the calibration technique and the sensitivity of all the channels.

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., Comment: changes to reflect version accepted by ApJ

The BOOMERanG experiment has recently produced detailed maps of the Cosmic Microwave Background, where sub-horizon structures are resolved with good signal to noise ratio. A power spectrum (spherical harmonics) analysis of the maps detects three peaks, at multipoles ℓ = (213_(-13)^(+10)),(541_(-32)^(+20))(845_(-25)^(+12)). In this paper we discuss the data analysis and the implications of these results 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: $\Omega_{\rm tot} = 1.02^{+0.06}_{-0.05}$ {\it vs.} $1.04 \pm 0.05$, $\Omega_b h^2 = 0.022^{+0.004}_{-0.003}$ {\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., Comment: 15 pages, 6 figures, submitted to Ap.J

The anisotropy of the cosmic microwave background radiation contains information about the contents and history of the universe. We report new limits on cosmological parameters derived from the angular power spectrum measured in the first Antarctic flight of the Boomerang experiment. Within the framework of models with adiabatic perturbations, and using only weakly restrictive prior probabilities on the age of the universe and the Hubble expansion parameter h, we find that the curvature is consistent with flat and that the primordial fluctuation spectrum is consistent with scale invariant, in agreement with the basic inflation paradigm. We find that the data prefer a baryon density Ωbh2 above, though similar to, the estimates from light element abundances and big bang nucleosynthesis. When combined with large scale structure observations, the Boomerang data provide clear detections of both dark matter and dark energy contributions to the total energy density Ωtot, independent of data from high-redshift supernovae.

The CMB is the fundamental tool to study the properties of the early universe and of the universe at large scales. In the framework of the Hot Big Bang model, when we look to the CMB we look back in time to the end of the plasma era, at a redshift ~ 1000, when the universe was ~ 50000 times younger, ~ 1000 times hotter and ~ 10^9 times denser than today. The image of the CMB can be used to study the physical processes there, to infer what happened before, and also to study the background geometry of our Universe.

BOOMERanG has recently resolved structures on the last scattering surface at redshift ˜ 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.

We report the first results from the BOOMERanG experiment, which mapped at 90, 150, 240 and 410 GHz a wide (3%) region of the microwave sky with minimal local contamination. From the data of the best 150 GHz detector we find evidence for a well defined peak in the power spectrum of temperature fluctuations of the Cosmic Microwave Background, localized at $\ell = 197 \pm 6$, with an amplitude of $(68 \pm 8) \mu K_{CMB}$. The location, width and amplitude of the peak is suggestive of acoustic oscillations in the primeval plasma. In the framework of inflationary adiabatic cosmological models the measured spectrum allows a Bayesian estimate of the curvature of the Universe and of other cosmological parameters. With reasonable priors we find $\Omega = (1.07 \pm 0.06)$ and $n_s = (1.00 \pm 0.08)$ (68%C.L.) in excellent agreement with the expectations from the simplest inflationary theories. We also discuss the limits on the density of baryons, of cold dark matter and on the cosmological constant., Comment: Proc. of the CAPP2000 conference, Verbier, 17-28 July 2000

We have performed a likelihood analysis of the recent data on the Cosmic Microwave Background Radiation (CMBR) anisotropy taken by the Boomerang experiment. We find that this data places a strong upper bound on the radiation density present at recombination. Expressed in terms of the equivalent number of neutrino species the $2\sigma$ bound is N_nu < 13, and the standard model prediction, N_nu = 3.04, is completely consistent the the data. This bound is complementary to the one found from Big Bang nucleosynthesis considerations in that it applies to any type of radiation, i.e. it is not flavour sensitive. It also applies to the universe at a much later epoch, and as such places severe limits on scenarios with decaying neutrinos. The bound also yields a firm upper limit on the lepton asymmetry in the universe., Comment: 4 pages, 2 postscript figures, matches version to appear in PRL

We use the angular power spectrum of the Cosmic Microwave Background, measured during the North American test flight of the BOOMERANG experiment, to constrain the geometry of the universe. Within the class of Cold Dark Matter models, we find that the overall fractional energy density of the universe, Omega, is constrained to be 0.85 < Omega < 1.25 at the 68% confidence level. Combined with the COBE measurement and the high redshift supernovae data we obtain new constraints on the fractional matter density and the cosmological constant., 4 pages, 3 figures LaTeX, emulateapj.sty

We describe a measurement of the angular power spectrum of anisotropies in the Cosmic Microwave Background (CMB) from 0.3 degrees to ~10 degrees from the North American test flight of the BOOMERANG experiment. BOOMERANG is a balloon-borne telescope with a bolometric receiver designed to map CMB anisotropies on a Long Duration Balloon flight. During a 6-hour test flight of a prototype system in 1997, we mapped > 200 square degrees at high galactic latitudes in two bands centered at 90 and 150 GHz with a resolution of 26 and 16.6 arcmin FWHM respectively. Analysis of the maps gives a power spectrum with a peak at angular scales of ~1 degree with an amplitude ~70 uK., 5 pages, 1 figure LaTeX, emulateapj.sty

The existence and anisotropy of the cosmic microwave background (CMB), the large scale distribution of Galaxies, the expansion of the Universe and the abundance of light elements can be all be explained with a single cosmological model. In this paper we focus on the CMB anisotropy maps produced by the BOOMERanG experiment and on their impact on cosmology. The images are consistent with the result of acoustic oscillations of the photons-matter plasma in the pre-recombination Universe (z ≳ 1000). We show how the instrument and the observations have been optimized and how the basic parameters of the model are derived from the data. These observations of the CMB are gaussian and point to a low curvature Universe (ω ∼ 1), as expected in the inflation scenario. In order to fit these observations and other cosmological evidence, the composition of the Universe must have significant contributions from dark matter (ω m ∼ 0.3) and dark energy (ωΛ ∼ 0.7).

The BOOMERanG experiment has recently detected temperature fluctuations the Cosmic Microwave Background (CMB), the otherwise isotropic radiation coming from the early Universe. These anisotropies have a low contrast (about 30 ppm) and feature a peculiar angular power spectrum at angles corresponding to sub-horizon scales at recombination. In the current cosmological model, these structures result from acoustic oscillations in the primeval plasma. In the framework of the Hot Big Bang theory with the inflationary hypothesis, the statistical properties of the image of the CMB allow us to measure most of the cosmological parameters.

The BOOMERanG experiment is a stratospheric balloon telescope intended to measure the Cosmic Microwave Background anisotropy at angular scales between a few degrees and ten arcminutes. The experiment features a wide focal plane with 16 detectors in the frequency bands centered at 90, 150, 220, 400 GHz, with FWHM ranging between 18 and 10 arcmin. It will be flown on a long duration (7-14 days) flight circumnavigating Antarctica at the end of 1998. The instrument was flown with a reduced focal plane (6 detectors, 90 and 150 GHz bands, 25 to 15 arcmin FWHM) on a qualification flight from Texas, in August 1997. A wide (~300 sq. deg, i.e. about 5000 independent beams at 150 GHz) sky area was mapped in the constellations of Capricornus, Aquarius, Cetus, with very low foreground contamination. The instrument was calibrated using the CMB dipole and observations of Jupiter. The LDB version of the instrument has been qualified and shipped to Antarctica., 12 pages, 9 figures

We describe the BOOMERanG experiment, a stratospheric balloon telescope intended to measure the Cosmic Microwave Background anisotropy at angular scales between a few degrees and ten arcminutes. The experiment has been optimized for a long duration (7 to 14 days) flight circumnavigating Antarctica at the end of 1998. A test flight was performed on Aug.30, 1997 in Texas. The level of performance achieved in the test flight was satisfactory and compatible with the requirements for the long duration flight., 11 pages, 6 figures

In the 1998-99 flight, BOOMERanG has produced maps of $\sim 4 %$ of the sky at high Galactic latitudes, at frequencies of 90, 150, 240 and 410 GHz, with resolution $\simgt 10'$. The faint structure of the Cosmic Microwave Background at horizon and sub-horizon scales is evident in these maps. These maps compare well to the maps recently obtained at lower frequencies by the WMAP experiment. Here we compare the amplitude and morphology of the structures observed in the two sets of maps. We also outline the polarization sensitive version of BOOMERanG, which was flown early this year to measure the linear polarization of the microwave sky at 150, 240 and 350 GHz., Comment: IAU Symposium 216: Maps of the Cosmos. Sydney 14-17 July 2003 - ASP Conference Series