We present results from a test for the Gaussianity of the whole sky subdegree‐scale cosmic microwave background (CMB) temperature anisotropy measured by the Wilkinson Microwave Anisotropy Probe (WMAP). We calculate the genus from the foreground‐subtracted and Kp0‐masked WMAP maps and measure the genus shift parameters defined at negative and positive threshold levels (Δν− and Δν+) and the asymmetry parameter (Δg) to quantify the deviation from the Gaussian relation. At WMAP Q, V and W bands, the genus and genus‐related statistics imply that the observed CMB sky is consistent with a Gaussian random phase field. However, from the genus measurement on the Galactic northern and southern hemispheres, we have found two non‐Gaussian signatures at the W‐band resolution ( scale), i.e. the large difference of genus amplitudes between the north and the south and the positive genus asymmetry in the south, which are statistically significant at 2.6σ and 2.4σ levels, respectively. The large genus amplitude difference also appears in the WMAP Q‐ and V‐band maps, deviating from the Gaussian prediction with a significance level of about 2σ. The probability that the genus curves show such a large genus amplitude difference exceeding the observed values at all Q, V and W bands in a Gaussian sky is only 1.4 per cent. Such non‐Gaussian features are reduced as the higher Galactic cut is applied, but their dependence on the Galactic cut is weak. We discuss possible sources that can induce non‐Gaussian features, such as the Galactic foregrounds, the integrated Sachs–Wolfe and the Sunyaev–Zel'dovich effects, and the reionization‐induced low ℓ‐mode non‐Gaussianity that are aligned along the Galactic plane. We conclude that CMB data with higher signal‐to‐noise ratio and an accurate foreground model are needed to understand the non‐Gaussian signatures.

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Axion as a coherently oscillating scalar field is known to behave as a cold dark matter in all cosmologically relevant scales. For conventional axion mass with 10 −5 eV, the axion reveals a characteristic damping behavior in the evolution of density perturbations on scales smaller than the solar system size. The damping scale is inversely proportional to the square-root of the axion mass. We show that the axion mass smaller than 10 −24 eV induces a significant damping in the baryonic density power spectrum in cosmologically relevant scales, thus deviating from the cold dark matter in the scale smaller than the axion Jeans scale. With such a small mass, however, our basic assumption about the coherently oscillating scalar field is broken in the early universe. This problem is shared by other dark matter models based on the Bose-Einstein condensate and the ultra-light scalar field. We introduce a simple model to avoid this problem by introducing evolving axion mass in the early universe, and present observational effects of present-day low-mass axion on the baryon density power spectrum, the cosmic microwave background radiation (CMB) temperature power spectrum, and the growth rate of baryon density perturbation. In our low-mass axion model we have a characteristic small-scale cutoff in the baryon density power spectrum below the axion Jeans scale. The small-scale deviations from the cold dark matter model in both matter and CMB power spectra clearly differ from the ones expected in the cold dark matter model mixed with the massive neutrinos as a hot dark matter component. 95.35.+d

We constrain spatially-flat tilted and nonflat untilted scalar field (φ) dynamical dark energy inflation (φCDM) models by using Planck 2015 cosmic microwave background (CMB) anisotropy measurements and recent baryonic acoustic oscillation distance observations, Type Ia supernovae apparent magnitude data, Hubble parameter measurements, and growth rate data. We assume an inverse power-law scalar field potential energy density V (φ) = V 0 φ −α . We find that the combination of the CMB data with the four non-CMB data sets significantly improves parameter constraints and strengthens the evidence for nonflatness in the nonflat untilted φCDM case from 1.8σ for the CMB measurements only to more than 3.1σ for the combined data. In the nonflat untilted φCDM model current observations favor a spatially closed universe with spatial curvature contributing about two-thirds of a percent of the present cosmological energy budget. The flat tilted φCDM model is a 0.4σ better fit to the data than is the standard flat tilted ΛCDM model: current data allow for the possibility that dark energy is dynamical. The nonflat tilted φCDM model is in better accord with the Dark Energy Survey bounds on the rms amplitude of mass fluctuations now (σ 8 ) as a function of the nonrelativistic matter density parameter now (Ω m ) but it does not provide as good a fit to the larger-multipole Planck 2015 CMB anisotropy data as does the standard flat tilted ΛCDM model. A few cosmological parameter value measurements differ significantly when determined using the tilted flat and the untilted nonflat φCDM models, including the cold dark matter density parameter and the reionization optical depth. Subject headings: cosmological parameters -cosmic background radiation -large-scale structure of universe -inflation -observations -methods:statistical arXiv:1807.07421v2 [astro-ph.CO]

We have produced a cleaned map of the Wilkinson Microwave Anisotropy Probe (WMAP) three-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 ( Figure 4b, available on-line), we have investigated the known anomalies in CMB maps at large scales, namely the low quadrupole (l = 2) power, and the strong alignment and planarity of the quadrupole and the octopole (l = 3). Our estimates are consistent with the previous measurements. The quadrupole and the octopole powers measured from our ILC map are δT 2 2 = 276 +94 −126 µK 2 and δT 2 3 = 952 +64 −83 µK 2 , respectively. The 68% confidence limits are estimated from the ILC simulations and include the cosmic variance. The measured quadrupole power is lower than the value expected in the concordance ΛCDM model (1250 µK 2 ), in which the probability of finding a quadrupole power lower than the measured value is 5.7%. We have confirmed that the quadrupole and the octopole are strongly aligned with angle θ 23 = 11. • 8 +6.• 4 −8.• 0 , and are planar with high planarity parameters t = 0.98 +0.02 −0.02 for l = 2 and t = 0.91 +0.02 −0.03 for l = 3. The observed angular separation θ 23 is marginally statistically significant because the probability of finding the angular separation as low as the observed value is 4.3%. However, the observed planarity is not statistically significant. The probability of observing such a planarity as high as the measured t values is over 18%. The ILC simulations show that the residual foreground emission in the ILC map does not affect the estimated values significantly. The large scale modes (l = 2-8) of SILC400 shows anti-correlation with the Galactic foreground emission on the southern hemisphere. It is not clear whether such anti-correlation occurs due to the residual Galactic emission or by chance.

We use the physically-consistent tilted spatially-flat and untilted non-flat ΛCDM inflation models to constrain cosmological parameter values with the Planck 2015 cosmic microwave background (CMB) anisotropy data and recent Type Ia supernovae measurements, baryonic acoustic oscillations (BAO) data, growth rate observations, and Hubble parameter measurements. The most dramatic consequence of including the four non-CMB data sets is the significant strengthening of the evidence for non-flatness in the non-flat ΛCDM model, from 1.8σ for the CMB data alone to 5.1σ for the full data combination. The BAO data is the most powerful of the non-CMB data sets in more tightly constraining model parameter values and in favoring a spatially-closed Universe in which spatial curvature contributes about a percent to the current cosmological energy budget. The untilted non-flat ΛCDM model better fits the large-angle CMB temperature anisotropy angular spectrum and is more consistent with the Dark Energy Survey constraints on the current value of the rms amplitude of mass fluctuations (σ 8 ) as a function of the current value of the nonrelativistic matter density parameter (Ω m ) but does not provide as good a fit to the smaller-angle CMB temperature anisotropy data as does the tilted flat-ΛCDM model. Some measured cosmological parameter values differ significantly between the two models, including the reionization optical depth and the baryonic matter density parameter, both of whose 2σ ranges (in the two models) are disjoint or almost so. Subject headings: cosmological parameters -cosmic background radiation -large-scale structure of universe -inflation -observations -methods:statistical

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