Powerful constraints on theories can already be inferred from existing CMB anisotropy data. But performing an exact analysis of available data is a complicated task and may become prohibitively so for upcoming experiments with 104 pixels. We present a method for approximating the likelihood that takes power spectrum constraints, e.g., "band-powers," as inputs. We identify a bias which results if one approximates the probability distribution of the band-power errors as Gaussian—as is the usual practice. This bias can be eliminated by using specific approximations to the non-Gaussian form for the distribution specified by three parameters (the maximum likelihood or mode, curvature or variance, and a third quantity). We advocate the calculation of this third quantity by experimenters, to be presented along with the maximum-likelihood band-power and variance. We use this non-Gaussian form to estimate the power spectrum of the CMB in 11 bands from multipole moment l = 2 (the quadrupole) to l = 3000 from all published band-power data. We investigate the robustness of our power spectrum estimate to changes in these approximations as well as to selective editing of the data.

Radical Compression of Cosmic Microwave Background Data

Observations of the microwave sky using the Python telescope in its fifth season of operation at the Amundsen-Scott South Pole Station in Antarctica are presented. The system consists of a 0.75 m off-axis telescope instrumented with a HEMT amplifier-based radiometer having continuum sensitivity from 37 to 45 GHz in two frequency bands. With a 091 × 102 beam, the instrument fully sampled 598 deg2 of sky, including fields measured during the previous four seasons of Python observations. Interpreting the observed fluctuations as anisotropy in the cosmic microwave background, we place constraints on the angular power spectrum of fluctuations in eight multipole bands up to l ~ 260. The observed spectrum is consistent with both the COBE experiment and previous Python results. There is no significant contamination from known foregrounds. The results show a discernible rise in the angular power spectrum from large (l ~ 40) to small (l ~ 200) angular scales. The shape of the observed power spectrum is not a simple linear rise, but has a sharply increasing slope starting at l ~ 150.

Anisotropy in the Cosmic Microwave Background at Degree Angular Scales: Python V Results

We present the analysis of the first 18 months of data obtained with the COSMOSOMAS (COSMOlogical Structures On Medium Angular Scales) experiment at the Teide Observatory (Tenerife). Three maps have been obtained at 12.7, 14.7 and 16.3 GHz covering 9000 deg 2 each with a resolution of ∼ 1 ° and with sensitivities 49, 59 and 115 μK beam -1 , respectively. These data in conjunction with the Wilkinson Microwave Anisotropy Probe (WMAP) first year maps have revealed that the cosmic microwave background (CMB) is the dominant astronomical signal at high galactic latitude (|b| > 40°) in the three COSMOSOMAS channels with an average amplitude of 29.7 ± 1.0 μK (68 per cent c.1. not including calibration errors). This value is in agreement with the predicted CMB signal in the COSMOSOMAS maps using the best-fitting A-CDM model to the WMAP power spectrum. Cross-correlation analysis of the 408-MHz map and the COSMOSOMAS data at high galactic latitudes give values in the range 17.0-14.4 μK from 12.7 to 16.3 GHz. Removing detected point sources in this template, reduces the amplitude of the correlated signal to 8-9 μK. The mean spectral index of the correlated signal between the 408 MHz desourced and the COSMOSOMAS maps is between -3.20 and -2.94 at |b| > 40° which indicates that this signal is due to synchrotron emission. Cross-correlation of COSMOSOMAS data with the Diffuse Infrared Background Experiment (DIRBE) map at 100 μm shows the existence of a common signal with amplitude 7.4 ± 1.1, 7.5 ± 1.1 and 6.5 ± 2.3 μK in the 12.7, 14.7 and 16.3 GHz COSMOSOMAS maps at |b| > 30°. Using the WMAP data, we find this DIRBE correlated signal rises from high to low frequencies flattening below ∼20 GHz. At higher galactic latitudes the average amplitude of the correlated signal with the DIRBE maps decreases slightly. The frequency behaviour of the COSMOSOMAS/WMAP correlated signal with DIRBE is not compatible with the expected tendency for thermal dust. A study of the Ha emission maps do not support free-free as a major contributor to that signal. Our results provide new evidence of a Galactic foreground with properties compatible with predictions by spinning dust models.

/pdf/observations-of-the-cosmic-microwave-background-and-galactic-4e8tf6wxd2.pdf

Observations of the cosmic microwave background and galactic foregrounds at 12–17-GHz with the COSMOSOMAS experiment

We use data from the ARGO cosmic microwave background (CMB) anisotropy experiment to constrain cosmogonies. We account for the ARGO beamwidth and calibration uncertainties, and we marginalize over the offset removed from the data. Our derived amplitudes of the CMB anisotropy detected by the ARGO experiment are smaller than those derived previously. We consider open and spatially flat-Λ cold dark matter cosmogonies, with the clustered-mass density parameter Ω0 in the range 0.1-1, the baryonic-mass density parameter ΩB in the range 0.005-0.029 h−2, and the age of the universe t0 in the range 10-20 Gyr. Marginalizing over all parameters but Ω0, the ARGO data favor an open (spatially flat-Λ) model with Ω0=0.23 (0.1). However, these numerical values are model dependent. At the 2 σ confidence level, model normalizations deduced from the ARGO data are consistent with those drawn from the UCSB South Pole 1994, MAX 4+5, White Dish, and SuZIE data sets. The ARGO open-model normalizations are also consistent with those deduced from the Differential Microwave Radiometer (DMR) data. However, for most spatially flat-Λ models, the DMR normalizations are more than 2 σ above the ARGO ones.

https://iopscience.iop.org/article/10.1086/306577/pdf

ARGO Cosmic Microwave Background Anisotropy Measurement Constraints on Open and Flat-Λ Cold Dark Matter Cosmogonies

We study the effects of diffuse Galactic, far-infrared extragalactic source, and radio point source emission on the cosmic microwave background (CMB) anisotropy data anticipated from the MAP experiment. We focus on the correlation function and genus statistics measured from mock MAP foreground-contaminated CMB anisotropy maps generated in a spatially-flat cosmological constant dominated cosmological model. Analyses of the simulated MAP data at 90 GHz (0.3 deg FWHM resolution smoothed) show that foreground effects on the correlation function are small compared with cosmic variance. However, the Galactic emission, even just from the region with |b| > 20 deg, significantly affects the topology of CMB anisotropy, causing a negative genus shift non-Gaussianity signal. Given the expected level of cosmic variance, this effect can be effectively reduced by subtracting existing Galactic foreground emission models from the observed data. IRAS and DIRBE far-infrared extragalactic sources have little effect on the CMB anisotropy. Radio point sources raise the amplitude of the correlation function considerably on scales below 0.5 deg. Removal of bright radio sources above a 5 \sigma detection limit effectively eliminates this effect. Radio sources also result in a positive genus curve asymmetry (significant at 2 \sigma) on 0.5 deg scales. Accurate radio point source data is essential for an unambiguous detection of CMB anisotropy non-Gaussianity on these scales. Non-Gaussianity of cosmological origin can be detected from the foreground-subtracted CMB anisotropy map at the 2 \sigma level if the measured genus shift parameter |\Delta\nu| >= 0.02 (0.04) or if the measured genus asymmetry parameter |\Delta g| >= 0.03 (0.08) on a 0.3 (1.0) deg FWHM scale.

https://arxiv.org/pdf/astro-ph/0107004.pdf

Effects of Foreground Contamination on the Cosmic Microwave Background Anisotropy Measured by MAP

During the fifth flight of the Microwave Anisotropy Experiment (MAX5), we revisited a region with significant dust emission near the star Mu Pegasi. A 3.5 cm$^{-1}$ low frequency channel has been added since the previous measurement (\cite{mei93a}). The data in each channel clearly show structure correlated with IRAS 100 \micron\ dust emission. The spectrum of the structure in the 6, 9 and 14 cm$^{-1}$ channels is described by $I_{\nu}\propto\nu^{\beta}B_{\nu}(T_{dust})$, where $\beta$ = 1.3 and $T_{dust}$ = 19~K and $B_{\nu}$ is the Planck function. However, this model predicts a smaller amplitude in the 3.5 cm$^{-1}$ band than is observed. Considering only linear combinations of the data independent of the best fit foreground spectrum for the three lower channels, we find an upper limit to CMBR fluctuations of $\Delta T/T = \langle \frac{C_l~l(l+1)}{2\pi}\rangle^{\frac{1}{2}} \leq 1.3\times 10^{-5}$ at the 95\% confidence level. The result is for a flat band power spectrum and does not include a 10\% uncertainty in calibration. It is consistent with our previous observation in the region.

https://arxiv.org/pdf/astro-ph/9605142.pdf

The Second Measurement of Anisotropy in the Cosmic Microwave Background Radiation at 0\fdg5 Scales near the Star Mu Pegasi

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The Second Measurement of Anisotropy in the Cosmic Microwave Background Radiation at 0\fdg5 Scales near the Star Mu Pegasi