The WMAP satellite has made available high quality maps of the sky in five frequency bands ranging from 22 to 94 GHz, with the main scientific objective of studying the anisotropies of the Cosmic Microwave Background (CMB). These maps, however, contain a mixture of emissions from various astrophysical origins, superimposed on CMB emission. The objective of the present work is to make a high resolution CMB map in which contamination by such galactic and extra-galactic foregrounds, as well as by instrumental noise, is as low as possible. The method used is an implementation of a constrained linear combination of the channels with minimum error variance, and of Wiener filtering, on a frame of spherical wavelets called needlets, allowing localised filtering in both pixel space and harmonic space. We obtain a low contamination low noise CMB map at the resolution of the WMAP W channel, which can be used for a range of scientific studies. We obtain also a Wiener-filtered version with minimal integrated error. The resulting CMB maps offer significantly better rejection of galactic foregrounds than previous CMB maps from WMAP data. They can be considered as the most precise full-sky CMB temperature maps to-date.
We present a circular cross-correlation tests for the phases of the Internal Linear Combination Map (ILC) and {\it WMAP}'s foregrounds for all K--W frequency bands at the range of multipoles $\ell\le 50$. We have found significant deviations from the expected Poissonian statistics for the ILC and the foregrounds phases. Our analysis shows that the low multipole range of the ILC power spectrum contains some of the foregrounds residues.
WMAP has provided CMB maps of the full sky. The raw data is subject to foreground contamination, in particular near to the Galactic plane. Foreground cleaned maps have been derived, e.g., the internal linear combination (ILC) map of Bennett et al. and the reduced foreground TOH map of Tegmark et al. Using S statistics we examine whether residual foreground contamination is left over in the foreground cleaned maps. In particular, we specify which parts of the foreground cleaned maps are sufficiently accurate for the circle-in-the-sky signature. We generalise the S statistic, called D statistic,…
We present an analysis of the foreground emission present in the WMAP 3-year data as determined by the method of Independent Component Analysis. We derived coupling coefficients between the WMAP data and foreground templates which are then used to infer the spectral behaviour for three foreground components -- synchrotron, anomalous dust-correlated emission and free-free. For the first two components, we find values consistent with previous results although slightly steeper. We confirm the inconsistency in the scaling between the Ha template and free-free emission at K- and Ka-bands where an e…
We present circular and linear cross-correlation tests and the "friend-of-friend" analysis for phases of the Internal Linear Combination Map (ILC) and the WMAP foregrounds for all K--W frequency bands at the range of multipoles $\ell\le100$. We compare also Tegmark, de Oliveira-Costa and Hamilton (2003) and Naselsky et al. (2003) cleaned maps with corresponding foregrounds. We have found significant deviations from the expected Poissonian statistics for all the cleaned maps and foregrounds. Our analysis shows that, for a low multipole range of the cleaned maps, power spectra contains some of t…
We present an application of the fast Independent Component Analysis (FastICA) to the WMAP 3yr data with the goal of extracting the CMB signal. We evaluate the confidence of our results by means of Monte Carlo simulations including CMB, foreground contaminations and instrumental noise specific of each WMAP frequency band. We perform a complete analysis involving all or a subset of the WMAP channels in order to select the optimal combination for CMB extraction, using the frequency scaling of the reconstructed component as a figure of merit. We found that the combination KQVW provides the best C…
We present a detailed analysis on the phases of the WMAP foregrounds (synchrotron, free-free and dust emission) of the WMAP K-W bands in order to estimate the significance of the variation of the spectral indices at different components. We first extract the spectral-index varying signals by assuming that the invariant part among different frequency bands have 100% cross-correlation of phases. We then use the minimization of variance, which is normally used for extracting the CMB signals, to extract the frequency independent signals. Such a common signal in each foreground component could play…
Recently a symmetry-based method to test for statistical isotropy of the cosmic microwave background was developed. We apply the method to template-cleaned 3-year and 5-year WMAP-$DA$ maps. We examine a wide range of angular multipoles from $2 < l < 300$. The analysis detects statistically signicant signals of anisotropy inconsistent with an isotropic CMB in some of the foreground cleaned maps. We are unable to resolve whether the anomalies have a cosmological, local astrophysical or instrumental origin. Assuming the anisotropy arises due to residual foreground contamination, we estimate the r…
We analyse the temperature-polarization cross-correlation in the Galactic synchrotron template that we have recently developed, and between the template and CMB temperature maps derived from WMAP data. Since the polarized synchrotron template itself uses WMAP data, we can estimate residual synchrotron contamination in the CMB $C_\ell^{TE}$ angular spectrum. While $C_2^{TE}$ appears to be contamined by synchrotron, no evidence for contamination is found in the multipole range which is most relevant for the fit of the cosmological optical depth.
Cosmologists have suggested a number of intriguing hypotheses for the origin of the "WMAP cold spot", the coldest extended region seen in the CMB sky, including a very large void and a collapsing texture. Either hypothesis predicts a distinctive CMB lensing signal. We show that the upcoming generation of high resolution CMB experiments such as ACT and SPT should be able to detect the signatures of either textures or large voids. If either signal is detected, it would have profound implications for cosmology.
We investigate the effect of foreground residuals in the WMAP data (Bennet et al. 2004) by adding foreground contamination to Gaussian ensembles of CMB signal and noise maps. We evaluate a set of non-Gaussian estimators on the contaminated ensembles to determine with what accuracy any residual in the data can be constrained using higher order statistics. We apply the estimators to the raw and cleaned Q, V, and W band first year maps. The foreground subtraction method applied to clean the data in Bennet et al. (2004a) appears to have induced a correlation between the power spectra and normalize…
The statistical expectation values of the temperature fluctuations of cosmic microwave background (CMB) are assumed to be preserved under rotations of the sky. We investigate the statistical isotropy of the CMB anisotropy maps recently measured by the Wilkinson Microwave Anisotropy Probe (WMAP) using bipolar spherical harmonic power spectrum proposed in Hajian & Souradeep 2003. The Bipolar Power Spectrum (BiPS) is estimated for the full sky CMB anisotropy maps of the first year WMAP data. The method allows us to isolate regions in multipole space and study each region independently. This searc…
We perform an independent foreground analysis of the WMAP maps to produce a cleaned CMB map (available online) useful for cross-correlation with, e.g., galaxy and X-ray maps. We use a variant of the Tegmark & Efstathiou (1996) technique that is completely blind, making no assumptions about the CMB power spectrum, the foregrounds, WMAP detector noise or external templates. Compared with the foreground-cleaned internal linear combination map produced by the WMAP team, our map has the advantage of containing less non-CMB power (from foregrounds and detector noise) outside the Galactic plane. The …
We perform a blind multi-component analysis of the WMAP 1 year foreground cleaned maps using SMICA (Spectral Matching Independent Component Analysis). We provide a new estimate of the CMB power spectrum as well as the amplitude of the CMB anisotropies across frequency channels. We show that the CMB anisotropies are compatible with temperature fluctuations as expected from the standard paradigm. The analysis also allows us to identify and separate a weak residual galactic emission present significantly in the Q-band outside of the Kp2 mask limits, and mainly concentrated at low galactic latitud…
We present a new method based on phase analysis for the Galaxy and foreground component separation from the cosmic microwave background (CMB) signal. This method is based on a prevailing assumption that the phases of the underlying CMB signal should have no or little correlation with those of the foregrounds. This method takes into consideration all the phases of each multipole mode (l <= 50, -l <= m <=l) from the whole sky without galactic cut, masks or any dissection of the whole sky into disjoint regions. We use cross correlation of the phases to illustrate that significant correlations of …
We study a specific correlation in spherical harmonic multipole domain for cosmic microwave background (CMB) analysis. This group of correlation between Δl=4n, n=1,2... is caused by symmetric signal in the Galactic coordinate system. An estimator targeting such correlation therefore helps remove the localized bright point-like sources in the Galactic plane and the strong diffused component down to the CMB level. We use 3 toy models to illustrate the significance of these correlations and apply this estimator on some derived CMB maps with foreground residuals. In addition, we show that our prop…
The non--Gaussian cold spot in the 1-year WMAP data, described in Vielva et al. and Cruz et al., is analysed in detail in the present paper. First of all, we perform a more rigorous calculation of the significance of the non-zero kurtosis detected in WMAP maps by Vielva et al. in wavelet space, mainly generated by the Spot. We confirm the robustness of that detection, since the probability of obtaining this deviation by chance is 0.69%. Afterwards, the morphology of the Spot is studied by applying Spherical Mexican Hat Wavelets with different ellipticities. The shape of the Spot is found to be…
In recent years the goal of estimating different cosmological parameters precisely has set new challenges in the effort to accurately measure the angular power spectrum of CMB. This has required removal of foreground contamination as well as detector noise bias with reliability and precision. Recently, a novel {\em model-independent} method for the estimation of CMB angular power spectrum solely from multi-frequency observations has been proposed and implemented on the first year WMAP data by Saha et al. 2006. All previous estimates of power spectrum of CMB are based upon foreground templates …
Polarization is the next frontier of CMB analysis, but its signal is dominated over much of the sky by foregrounds which must be carefully removed. To determine the efficacy of this cleaning it is necessary to have sensitive tests for residual foreground contamination in polarization sky maps. The dominant Galactic foregrounds introduce a large-scale anisotropy on to the sky, so it makes sense to use a statistic sensitive to overall directionality for this purpose. Here we adapt the rapidly computable D statistic of Bunn and Scott to polarization data, and demonstrate its utility as a foregrou…
We present a new estimate of foreground emission in the WMAP data, using a Markov chain Monte Carlo (MCMC) method. The new technique delivers maps of each foreground component for a variety of foreground models, error estimates of the uncertainty of each foreground component, and provides an overall goodness-of-fit measurement. The resulting foreground maps are in broad agreement with those from previous techniques used both within the collaboration and by other authors. We find that for WMAP data, a simple model with power-law synchrotron, free-free, and thermal dust components fits 90% of th…
We apply a Cross-correlation (CC) method developed previously for detecting gamma-ray point sources to the WMAP first year data by using the Point-Spread Function of WMAP and obtain a full sky CC coefficient map. Analyzing this map, we find that the CC method is a powerful tool to examine the WMAP foreground residuals which can be further cleaned accordingly. Evident foreground signals are found in WMAP foreground cleaned maps and Tegmark cleaned map. In this process 101 point-sources are detected, and 26 of them are new sources besides the originally listed WMAP 208 sources. We estimate the f…
B-modes of Cosmic Microwave Background (CMB) polarization can be created by a primordial gravitational wave background. If this background was created by Inflation, then the amplitude of the polarization signal is proportional the energy density of the universe during inflation. The primordial signal will be contaminated by polarized foregrounds including dust and synchrotron emission within the galaxy. In light of the WMAP polarization maps, we consider the ability of several hypothetical CMB polarization experiments to separate primordial CMB B-mode signal from galactic foregrounds. We also …
We have estimated the CMB variance from the three-year WMAP data, finding a value which is significantly lower than the one expected from Gaussian simulations using the WMAP best-fit cosmological model, at a significance level of 98.7 per cent. This result is even more prominent if we consider only the north ecliptic hemisphere (99.8 per cent). Different analyses have been performed in order to identify a possible origin for this anomaly. In particular we have studied the behaviour of single radiometers and single year data as well as the effect of residual foregrounds and 1/f noise, finding t…
The WMAP first year detection of a high redshift reionization through its imprints on CMB anisotropy T and TE mode angular power spectra calls for a better comprehension of the universe ionization and thermal history after the standard recombination. Different reionization mechanisms predict different signatures in the CMB, both in temperature and polarization anisotropies and in spectral distortions. The Planck capability to distinguish among different scenarios through its sensitivity to T, TE, and E mode angular power spectra is discussed. Perspectives open by future high sensitivity experi…
We cross correlate the Wilkinson Microwave Anisotropy Probe (WMAP) first year data and the diffuse gamma-ray intensity maps from the Energetic Gamma Ray Experiment Telescope (EGRET) using spherical wavelet approaches. Correlations at 99.7% significance level have been detected, at scales around $15^{\circ}$ in the WMAP foreground cleaned W-band and Q-band maps, based on data from regions that are outside the most conservative WMAP foreground mask; no significant correlation is found with the Tegmark cleaned map. The detected correlation is most likely of Galactic origin, and thus can help us p…
Using a Gibbs sampling algorithm for joint CMB estimation and component separation, we compute the large-scale CMB and foreground posteriors of the 3-yr WMAP temperature data. Our parametric data model includes the cosmological CMB signal and instrumental noise, a single power law foreground component with free amplitude and spectral index for each pixel, a thermal dust template with a single free overall amplitude, and free monopoles and dipoles at each frequency. This simple model yields a surprisingly good fit to the data over the full frequency range from 23 to 94 GHz. We obtain a new esti…
Accurate measurements of angular power spectrum of Cosmic Microwave Background (CMB) radiation has lead to marked improvement in the estimates of different cosmological parameters. This has required removal of foreground contamination as well as detector noise bias with reliability and precision. We present the estimation of CMB angular power spectrum from the multi-frequency observations of WMAP using a novel {\em model-independent} method. The primary product of WMAP are the observations of CMB in 10 independent difference assemblies (DA) that have uncorrelated noise. Our method utilizes max…
We investigate a possible asymmetry in the statistical properties of the cosmic microwave background temperature field and to do so we construct an estimator aiming at detecting a dipolar modulation. Such a modulation is found to induce correlations between multipoles with $Δ\ell=1$. Applying this estimator, to the V and W bands of the WMAP data, we found a significant detection in the V band. We argue however that foregrounds and in particular point sources are the origin of this signal.
It has been suggested by Roukema and coworkers (hereafter R04) that the topology of the Universe as probed by the ``matched circles'' method using the first year release of the WMAP CMB data, might be that of the Poincaré dodecahedral space (PDS) model. An excess in the correlation of the ``identified circles'' was reported by R04, for circles of angular radius of ~11 deg for a relative phase twist -36deg, hinting that this could be due to a Clifford translation, if the hypothesized model were true. R04 did not however specify the statistical significance of the correlation signal. We investig…
We perform multi-scale non-Gaussianity detection and localization to the Wilkinson Microwave Anisotropy Probe (WMAP) first-year data in both wavelet and real spaces. Such an analysis is facilitated by spherical wavelet transform and inverse transform techniques developed by the YAWtb team. Skewness and kurtosis as test statistics are calculated on scales from about $1^{\circ}$ to $30^{\circ}$ on the sky as well as toward different directions using anisotropic spherical Morlet wavelet (SMW). A maximum deviation from Gaussian simulations with a right tail probability of $\sim 99.9%$ is detected …
We have derived whole-sky CMB polarization maps from the WMAP 5 year polarization data, using the Harmonic Internal Linear Combination (HILC) method. Our HILC method incorporates spatial variability of linear weights in a natural way and yields continuous linear weights over the entire sky. To estimate the power spectrum of HILC maps, we have derived a unbiased quadratic estimator, which is similar to the WMAP team's cross power estimator, but in a more convenient form for HILC maps. From our CMB polarization map, we have obtained TE correlation and E mode power spectra without applying any ma…
Full sky maps are made in five microwave frequency bands to separate the temperature anisotropy of the CMB from foreground emission. We define masks that excise regions of high foreground emission. The effectiveness of template fits to remove foreground emission from the WMAP data is examined. These efforts result in a CMB map with minimal contamination and a demonstration that the WMAP CMB power spectrum is insensitive to residual foreground emission. We construct a model of the Galactic emission components. We find that the Milky Way resembles other normal spiral galaxies between 408 MHz and…
We study the SZ-effect-induced non-Gaussianity in the cosmic microwave background (CMB) fluctuation maps. If a CMB map is contaminated by the SZ effect of galaxies or galaxy clusters, the CMB maps should have similar non-Gaussian features as the galaxy and cluster fields. Using the WMAP data and 2MASS galaxy catalog we show that the non-Gaussianity of the 2MASS galaxies is imprinted on WMAP maps. The signature of non-Gaussianity can be seen with the 4^{th} order cross correlation between the wavelet variables of the WMAP maps and 2MASS clusters. The intensity of the 4^{th} order non-Gaussian f…
The existing analysis of WMAP data is based on approximations for the likelihood function, which is likely to be inaccurate on large scales. Here we present exact evaluations of the likelihood of the low multipoles by direct inversion of the theoretical covariance matrix for low resolution WMAP maps. We project out the unwanted galactic contaminants rather than subtract them, which can remove some of the cosmological signal and may lead to a suppression of power. We find an increase in power at low multipoles. For the quadrupole the maximum likelihood values are rather uncertain and vary betwe…
Recent analyses of the WMAP data have suggested that the low-order multipoles of the CMB anisotropy distribution show cosmologically interesting and unexpected morphologies and amplitudes. In this paper, we apply a power equalization (PE) filter to the high-latitude WMAP data in order to reconstruct these low-l multipoles free from the largest Galactic foreground modelling uncertainties in the Galactic plane. The characteristic spatial distributions of the modes of order l=2,3,4,5 have been determined as a function of frequency, sky coverage and two methods for foreground correction: using the…
Many recent analyses have indicated that large scale WMAP data display anomalies that appear inconsistent with the standard cosmological paradigm. However, the effects of foreground contamination, which require elimination of some fraction of the data, have not been carefully investigated due to the complexity in the analysis. Here we develop a general formalism of how to incorporate these effects in any analysis of this type. Our approach is to compute the full multi-dimensional probability distribution function of all possible sky realizations that are consistent with the data and with the a…
We are presenting an Internal Linear Combination (ILC) CMB map, in which the foreground is reduced through harmonic variance minimization. We have derived our method by converting a general form of pixel-space approach into spherical harmonic space, maintaining full correspondence. By working in spherical harmonic space, spatial variability of linear weights is incorporated in a self-contained manner and our linear weights are continuous functions of position over the entire sky. The full correspondence to pixel-space approach enables straightforward physical interpretation on our approach. In…
The issue of non-Gaussianity is not only related to distinguishing the theories of the origin of primordial fluctuations, but also crucial for the determination of cosmological parameters in the framework of inflation paradigm. We present an advenced method for testing non-Gaussianity on the whole-sky CMB anisotropies. This method is based on the Kuiper's statistic to probe the two-dimensional uniformity on a periodic mapping square associating phases: return mapping of phases of the derived CMB (similar to auto correlation) and cross correlations between phases of the derived CMB and foregrou…
Several accurate analyses of the CMB temperature maps from the Wilkinson Microwave Anisotropy Probe (WMAP) have revealed a set of anomalous results, at large angular scales, that appears inconsistent with the statistical isotropy expected in the concordance cosmological model $Λ$CDM. Because these anomalies seem to indicate a preferred direction in the space, here we investigate the signatures that a primordial magnetic field, possibly present in the photon-baryon fluid during the decoupling era, could have produced in the large-angle modes of the observed CMB temperature fluctuations maps. To…
The Correlated Component Analysis (CCA) allows us to estimate how the different diffuse emissions mix in CMB experiments, exploiting also complementary information from other surveys. It is especially useful to deal with possible additional components. An application of CCA to WMAP maps assuming that only the canonical Galactic emissions are present, highlights the widespread presence of a spectrally flat "synchrotron" component, largely uncorrelated with the synchrotron template, suggesting that an additional foreground is indeed required. We have tested various spectral shapes for such compo…
ABRIDGED: We introduce and analyze a method for testing statistical isotropy and Gaussianity and apply it to the WMAP CMB foreground reduced, temperature maps, and cross-channel difference maps. We divide the sky into regions of varying size and shape and measure the first four moments of the one-point distribution within these regions, and using their simulated spatial distributions we test the statistical isotropy and Gaussianity hypotheses. By randomly varying orientations of these regions, we sample the underlying CMB field in a new manner, that offers a richer exploration of the data cont…
The recent study of BOOMERanG 150 GHz Cosmic Microwave Background (CMB) radiation maps have detected ellipticity of the temperature anisotropy spots independent on the temperature threshold. The effect has been found for spots up to several degrees in size, where the biases of the ellipticity estimator and of the noise are small. To check the effect, now we have studied, with the same algorithm and in the same sky region, the WMAP maps. We find ellipticity of the same average value also in WMAP maps, despite of the different sensitivity of the two experiments to low multipoles. Large spot elon…
We estimate the accuracy with which various cosmological parameters can be determined from the CMB temperature and polarization data when various galactic unpolarized and polarized foregrounds are included and marginalized using the multi-frequency Wiener filtering technique. We use the specifications of the future CMB missions MAP and PLANCK for our study. Our results are in qualitative agreement with earlier results obtained without foregrounds, though the errors in most parameters are higher because of degradation of the extraction of polarization signal in the presence of foregrounds.
The recent WMAP data represents a milestone in cosmology and helps constrain cosmological parameters with unprecedented accuracy. In this work we combine the WMAP data with previous CMB anisotropy measurements at smaller angular scales to characterize the shape of the CMB anisotropy power spectrum. We carry out a phenomenological analysis of the data. By allowing non-physical shapes of the power spectrum we analyse high and low frequency experiments separately and together. We find that WMAP dramatically constrains the power spectrum up to l \~ 700. On smaller scales, the data show discrepanci…
We perform a wavelet analysis of the temperature and polarization maps of the Cosmic Microwave Background (CMB) delivered by the WMAP experiment in search for a parity violating signal. Such a signal could be seeded by new physics beyond the standard model, for which the Lorentz and CPT symmetries may not hold. Under these circumstances, the linear polarization direction of a CMB photon may get rotated during its cosmological journey, a phenomenon also called cosmological birefringence. Recently, Feng et al. have analyzed a subset the WMAP and BOOMERanG 2003 angular power spectra of the CMB, d…
We present the analysis on the quadrupole phases of the Internal Linear Combination map, ILC(I) and (III) derived by the WMAP team (1 and 3-year data release). This approach allows us to see the global trend of non-Gaussianity of the quadrupoles for the ILC(III) map through phase correlations with the foregrounds. Significant phase correlations is found in between the ILC(III) quadrupole and the WMAP foregrounds phases for K-W band: the phases of the ILC(III) quadrupole xi_{2,1}, xi_{2,2} and those of the foregrounds at K-W bands Phi_{2,1}, Phi_{2,2} display significant symmetry: xi_{2,1}+Phi_…
Although individual observational groups vigorously test their data sets for systematic errors, the pre-WMAP CMB observational data set has not yet been collectively tested. Under the assumption that the concordance model is the correct model, we have explored residuals of the observational data with respect to this model to see if any patterns emerge that can be identified with systematic errors. We found no significant trends associated with frequency, frequency channels, calibration source, pointing uncertainty, instrument type, platform and altitude. We did find some evidence at the ~ 1 to…
Local scaling properties of the co-added foreground-cleaned three-year Wilkinson Microwave Anisotropy Probe (WMAP) data are estimated using weighted scaling indices. The scaling index method (SIM) is - for the first time - adapted and applied to the case of spherical symmetric spatial data. The results are compared with 1000 Monte Carlo simulations based on Gaussian fluctuations with a best fit $Λ$CDM power spectrum and WMAP-like beam and noise properties. Statistical quantities based on the scaling indices, namely the moments of the distribution and probability-based measures are determined. …
The quadrupole power of cosmic microwave background (CMB) temperature anisotropies seen in the WMAP data is puzzlingly low. In this paper we demonstrate that Minimum Variance Optimization (MVO), a technique used by many authors (including the WMAP science team) to separate the CMB from contaminating foregrounds, has the effect of forcing the extracted CMB map to have zero statistical correlation with the foreground emission. Over an ensemble of universes the true CMB and foreground are indeed expected to be uncorrelated, but any particular sky pattern (such as the one we happen to observe) wil…
We apply spherical needlets to the Wilkinson Microwave Anisotropy Probe 5-year cosmic microwave background (CMB) dataset, to search for imprints of non-isotropic features in the CMB sky. We use the needlets localization properties to resolve peculiar features in the CMB sky and to study how these features contribute to the anisotropy power spectrum of the CMB. In addition to the now well-known "cold spot" of the CMB map in the southern hemisphere, we also find two hot spots at greater than 99% confidence level, again in the southern hemisphere and closer to the Galactic plane. While the cold s…
We present a full-sky model of polarized Galactic microwave emission based on three years of observations by the Wilkinson Microwave Anisotropy Probe (WMAP) at frequencies from 23 to 94 GHz. The model compares maps of the Stokes Q and U components from each of the 5 WMAP frequency bands in order to separate synchrotron from dust emission, taking into account the spatial and frequency dependence of the synchrotron and dust components. This simple two-component model of the interstellar medium accounts for at least 97% of the polarized emission in the WMAP maps of the microwave sky. Synchrotron …
Almost the totality of the bright foreground sources in the WMAP CMB maps are blazars, a class of sources that show usually also X-ray emission. However, 23 objects in a flux-limited sample of 140 blazars of the WMAP catalog (first year) were never reported before as X-ray sources. We present here the results of 41 Swift observations which led to the detection of all these 23 blazars in the 0.3-10 keV band. We conclude that all micro-wave selected blazars are X-ray emitters and that the distribution of the micro-wave to X-ray spectral slope $α_{mu x}$ of LBL blazars is very narrow, confirming …
We address the extended problem of component separation for CMB applications when a mixture of both astrophysical and instrumental components are present in the observations, and show how standard methods can be adapted to handle this more complex inversion problem.
The amplitudes of the quadrupole and octopole measured from the Wilkinson Microwave Anisotropy Probe (WMAP) appear to be lower than expected according to the concordance Lambda CDM cosmology. However, the pseudo-Cl estimator used by the WMAP team is non-optimal. In this paper, we discuss the effects of Galactic cuts on pseudo-Cl and quadratic maximum likelihood estimators. An application of a quadratic maximum likelihood estimator to Galaxy subtracted maps produced by the WMAP team and Tegmark, de Oliveira-Costa and Hamilton (2003) shows that the amplitudes of the low multipoles are stable to …
We use a simple model to investigate the effect of polarized Galactic foreground emission on the ability of planned CMB missions to detect and model CMB polarization. Emission from likely polarized sources (synchrotron and spinning dust) would dominate the polarization of the microwave sky at frequencies below 90 GHz if known Galactic foregrounds are at least 10% polarized at high latitude (|b| > 30 deg). Maps of polarization at frequencies below 90 GHz will likely require correction for foreground emission to enable statistical analysis of the individual Stokes Q or U components. The temperat…
Several accurate analyses have revealed a statistically significant North-South ecliptic asymmetry in the large-angle correlations strength of the Cosmic Microwave Background (CMB) radiation temperature field data from the Wilkinson Microwave Anisotropy Probe (WMAP). This asymmetry is inconsistent with the statistical isotropy expected in the concordance cosmological model LCDM. It has been suggested that a possible cause-effect relationship exists between this large-angle anisotropy and the anomalous CMB quadrupole-octopole planes alignment. In turn, this later phenomenon (or both) would be a…
A primordial cosmological magnetic field induces and supports vorticity or Alfven waves, which in turn generate cosmic microwave background (CMB) anisotropies. A homogeneous primordial magnetic field with fixed direction induces correlations between the $a_{l-1,m}$ and $a_{l+1,m}$ multipole coefficients of the CMB temperature anisotropy field. We discuss the constraints that can be placed on the strength of such a primordial magnetic field using CMB anisotropy data from the WMAP experiment. We place 3 $σ$ upper limits on the strength of the magnetic field of $B < 15$ nG for vector perturbation…
[Abridged] We have produced a cleaned map of the Wilkinson Microwave Anisotropy Probe (WMAP) 3-year data using an improved foreground subtraction technique. We perform an internal linear combination (ILC) to subtract the Galactic foreground emission from the temperature fluctuations observed by the WMAP. We divide the whole sky into hundreds of pixel groups with similar foreground spectral indices over a range of WMAP frequencies, apply the ILC for each group, and obtain a CMB map with foreground emission effectively reduced. With the resulting foreground-reduced ILC map, we have investigated …
One of the main obstacles in extracting the Cosmic Microwave Background (CMB) signal from observations in the mm-submm range is the foreground contamination by emission from galactic components: mainly synchrotron, free-free and thermal dust emission. Due to the statistical nature of the intrinsic CMB signal it is essential to minimize the systematic errors in the CMB temperature determinations. Following the available knowledge of the spectral behavior of the galactic foregrounds simple, power law-like spectra have been assumed. The feasibility of using a simple neural network for extracting …
We apply a previously developed Gibbs sampling framework to the foreground corrected 3-yr WMAP polarization data and compute the power spectrum and residual foreground template amplitude posterior distributions. We first analyze the co-added Q- and V-band data, and compare our results to the likelihood code published by the WMAP team. We find good agreement, and thus verify the numerics and data processing steps of both approaches. However, we also analyze the Q- and V-bands separately, allowing for non-zero EB cross-correlations and including two individual foreground template amplitudes trac…
We address the effect of an extended local foreground on the low-l anomalies found in the CMB. Recent X-ray catalogues point us to the existence of very massive superstructures at the 100 h^(-1) Mpc scale that contribute significantly to the dipole velocity profile. Being highly non-linear, these structures provide us a natural candidate to leave an imprint on the CMB sky via a local Rees-Sciama effect. We show that the Rees-Sciama effect of local foregrounds can induce CMB anisotropy of DeltaT/T ~ 10^(-5) and we analyse its impact on multipole power as well as the induced phase pattern on lar…
