O. V. Verkhodanov

Non-Gaussianity of the Derived Maps from the First-Year Wilkinson Microwave Anisotropy Probe Data

We present non-Gaussianity testing on recently-released derived maps from the first-year WMAP data by Tegmark, de Oliveria-Costa and Hamilton. Our test is based on a phase mapping technique which has the advantage of testing non-Gaussianity at separate multipole bands. We show that their foreground-cleaned map is against the random-phase hypothesis at all 4 multipole bands centered around l = 150, 290, 400 and 500. Their Wiener-filtered map, on the other hand, is Gaussian for l 350 as we detect certain degrees of phase coupling, hence against the random-phase hypothesis. Our phase mapping technique is particularly useful for testing the accuracy of component separation methods.We present non-Gaussianity testing on derived maps from the recently released first-year Wilkinson Microwave Anisotropy Probe data by Tegmark, de Oliveria-Costa, & Hamilton. Our test is based on a phase-mapping technique that has the advantage of testing non-Gaussianity at separate multipole bands. We show that their foreground-cleaned map is against the random-phase hypothesis at all four multipole bands centered around l = 150, 290, 400, and 500. Their Wiener-filtered map, on the other hand, is Gaussian for l 350 as we detect certain degrees of phase coupling, hence against the random-phase hypothesis. Our phase-mapping technique is particularly useful for testing the accuracy of component separation methods.

The Gauss-Legendre Sky Pixelization for the CMB polarization (GLESP-pol). Errors due to pixelization of the CMB sky

We present the development of the method for numerical analysis of polarization in the Gauss–Legendre sky pixelization (GLESP) scheme for CMB maps. This incorporation of the polarization transforms in the pixelization scheme GLESP completes the creation of our new method for numerical analysis of CMB maps. A comparison of GLESP and HEALPix calculations is done.

Understanding the WMAP Cold Spot mystery

The Cold Spot (CS) at galactic coordinates (b = −57°, l = 209°) was discovered in the Wilkinson Microwave Anisotropy Probe (WMAP)data as a cosmic background anomaly. In order to assess the cosmological significance of the Spot, we examine its properties using the cluster analysis of the local extrema in the cosmic microwave background (CMB) signal. We also check the hypothesis that the CMB signal has a non-Gaussian tail, localized in the low-multipole components. We constructed a linear filter, dividing the signal into two parts: non-Gaussian and Gaussian. Using the filter scale as a variable, we can maximize the skewness and kurtosis of the smoothed signal and minimize these statistics. We discovered that the shape of the CS is formed primarily by the components of the CMB signal represented by the multipoles between 10 ≤ ℓ ≤ 20, with a corresponding angular scale of about 5°–10°. This signal leads to the modulation of the CMB on the whole sky, clearly seen at |b| > 30° in both the ILC andWCM maps, rather than in a single localized feature. After subtraction of this modulation, the remaining part of the CMB signal appears to be consistent with statistical homogeneity and Gaussianity. We therefore infer that the mystery of the WMAP Cold Spot reflects directly the peculiarities of low multipoles of the CMB signal, rather than a single local (isolated) defect or the manifestations of a globally anisotropic cosmology.

Instability of reconstruction of the low CMB multipoles

We discuss the problem of the bias of the Internal Linear Combination (ILC) CMB map and show that it is closely related to the coefficient of cross-correlation K(ℓ) of the true CMB and the foreground for each multipole ℓ. We present analysis of the cross-correlation for the WMAP ILC quadrupole and octupole from the first (ILC(I)) and the third (ILC(III)) year data releases and show that these correlations are ∼ −0.52–0.6. Analysing 104 Monte Carlo simulations of the random Gaussian CMB signals, we show that the distribution function for the corresponding coefficient of the cross-correlation has a polynomial shape P(K, ℓ) ∝ (1 − K2)ℓ−1. We show that the most probable value of the cross-correlation coefficient of the ILC and foreground quadrupole has two extrema at K ≃ ±0.58. Thus, the ILC(III) quadrupole represents the most probable value of the coefficient K. We analyze the problem of debiasing of the ILC CMB and pointed out that reconstruction of the bias seems to be very problematic due to statistical uncertainties. In addition, instability of the debiasing illuminates itself for the quadrupole and octupole components through the flip-effect, when the even ℓ + m modes can be reconstructed with significant error. This error manifests itself as opposite, in respect to the true sign of even low multipole modes, and leads to significant changes of the coefficient of cross-correlation with the foreground. We show that the CMB realizations, whose the sign of quadrupole (2, 0) component is negative (and the same, as for all the foregrounds), the corresponding probability to get the positive sign after implementation of the ILC method is about 40%.

Tessellated mapping of cosmic background radiation correlations and source distributions

We offer a method of correlations mapping on the full celestial sphere that allows to check the quality of reconstructed maps, their non-Gaussianity and conduct experiments in various frequency ranges. The method was evaluated on the WMAP data, both on the reconstructed maps and foreground components, and on the NRAO VLA Sky Survey (NVSS) data. We detected a significant shift in the correlation data of the dust component, which can be preconditioned by a more complex dust model than the one currently in use for component separation. While studying the NVSS correlation data, we demonstrated that the statistics of the coinciding spots in the microwave background and in the NVSS survey corresponds to the one expected in the ΛCDM model. This can testify for a chance coincidence of the spots in the NVSS and WMAP data in the CMB Cold Spot region. Our method is software-implemented in the GLESP package. PACS: 95.75.-z, 98.62.Ve, 98.70.Dk, 98.70.Vc, 98.80.-kWe offer a method of correlations mapping on the full celestial sphere that allows to check the quality of reconstructed maps, their non-Gaussianity and conduct experiments in various frequency ranges. The method was evaluated on the WMAP data, both on the reconstructed maps and foreground components, and on the NRAO VLA Sky Survey (NVSS) data. We detected a significant shift in the correlation data of the dust component, which can be preconditioned by a more complex dust model than the one currently in use for component separation. While studying the NVSS correlation data, we demonstrated that the statistics of the coinciding spots in the microwave background and in the NVSS survey corresponds to the one expected in the ΛCDM model. This can testify for a chance coincidence of the spots in the NVSS and WMAP data in the CMB Cold Spot region. Our method is software-implemented in the GLESP package.

RC J0311+0507: A candidate for superpowerful radio galaxies in the early universe at redshift z = 4.514

A strong emission line at 6703 Å has been detected in the optical spectrum for the host galaxy (R = 23.1) of the radio source RC J0311+0507 (4C+04.11). This radio galaxy, with a spectral index of 1.31 in the frequency range 365–4850 MHz, is one of the ultrasteep-spectrum objects from the deep survey of a sky strip conducted with RATAN-600 in 1980–1981. We present arguments in favor of the identification of this line with Lyα at redshift z = 4.514. In this case, the object belongs to the group of extremely distant radio galaxies of ultrahigh radio luminosity (P1400 = 1.3 × 1029 W Hz−1). Such power can be provided only by a fairly massive black hole (∼109M⊙) that formed in a time less than the age of the Universe at the observed z (1.3 Gyr) or had a primordial origin.

Dominant Multipoles in WMAP5 Mosaic Data Correlation Maps

The method of correlation mapping on the full sphere is used to study the properties of the ILC map, as well as the dust and synchrotron background components. An anomalous correlation of the components with the ILC map in the main plane and in the poles of the ecliptic and equatorial coordinate systems was discovered. Apart from the bias, a dominant quadrupole contribution in the power spectrum of the mosaic correlation maps was found in the pixel correlation histogram. Various causes of the anomalous signal are discussed.The method of correlation mapping on the full sphere is used to study the properties of the ILC map, as well as the dust and synchrotron background components. An anomalous correlation of the components with the ILC map in the main plane and in the poles of the ecliptic and equatorial coordinate systems was discovered. Apart from the bias, a dominant quadrupole contribution in the power spectrum of the mosaic correlation maps was found in the pixel correlation histogram. Various causes of the anomalous signal are discussed.

Catalog of radio galaxies with z > 0.3. I: Construction of the sample

The procedure of the construction of a sample of distant (z > 0.3) radio galaxies using NED, SDSS, and CATS databases for further application in statistical tests is described. The sample is assumed to be cleaned from objects with quasar properties. Primary statistical analysis of the list is performed and the regression dependence of the spectral index on redshift is found.

Foreground analysis from the 1-year Wilkinson Microwave Anisotropy Probe (WMAP) data

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 a significant role for any kind of component separation methods, because the methods cannot discriminate frequency independent foregrounds and CMB.

Faraday rotation as a diagnostic of Galactic foreground contamination of cosmic microwave background maps

The contribution from the residuals of the foreground can have a significant impact on the temperature maps of the Cosmic Microwave Background (CMB). Mostly, the focus has been on the galactic plane, when foreground cleaning has taken place. However, in this paper, we will investigate the possible foreground contamination, from sources outside the galactic plane in the CMB maps. We will analyze the correlation between the Faraday rotation map and the CMB temperature map. The Faraday rotation map is dependent on the galactic magnetic field, as well as the thermal electron density, and both may contribute to the CMB temperature. We find that the standard deviation for the mean cross correlation deviate from that of simulations at the 99.9% level. Additionally, a comparison between the CMB temperature extrema and the extremum points of the Faraday rotation is also performed, showing a general overlap between the two. Also we find that the CMB Cold Spot is located at an area of strong negative cross correlation, meaning that it may be explained by a galactic origin. Further, we investigate nearby supernova remnants in the galaxy, traced by the galactic radio loops. These super nova remnants are located at high and low galactic latitude, and thus well outside the galactic plane. We find some correlation between the Faraday Rotation and the CMB temperature, at select radio loops. This indicate, that the galactic foregrounds may affect the CMB, at high galactic latitudes