Based on the postulate that photon propagation is governed by an SU(2) gauge principle we numerically compute the one‐loop dispersion for thermalized photon propagation on the radiatively induced mass shell. Formerly, the dispersion was addressed by assuming p2 = 0. While this approximation turns out to be excellent for temperatures ≤ 2 TCMB the exact result exhibits a much faster (power‐like) shrinking of the gap in the black‐body spectral intensity with rising temperature. Our previous statements on anomalous large‐angle CMB temperature‐temperature correlations, obtained in the approximation p2 = 0, remain valid. 相似文献
A review of the spatially flat cosmological model SU(2)CMB, minimally induced by the postulate that the cosmic microwave background (CMB) is subject to an SU(2) rather than a U(1) gauge principle, is given. Cosmological parameter values, which are determined from the Planck CMB power spectra at small angular scales, are compared to their values in spatially flat ΛCDM from both local and global extractions. As a global model SU(2)CMB leans toward local ΛCDM cosmology and is in tension with some global ΛCDM parameter values. Spectral antiscreening / screening effects in SU(2)CMB radiance are presented within the Rayleigh– Jeans regime in dependence on temperature and frequency. Such radiance anomalies can cause CMB large-angle anomalies. Therefore, it is pointed out how SU(2)CMB modifies the Boltzmann equation for the perturbations of the photon phase space distribution at low redshift and why this requires to the solve the ℓ-hierarchy on a comoving momentum grid (q-grid) for all z. 相似文献
Recent released WMAP data show a low value of quadrupole in the CMB temperature fluctuations, which confirms the early observations by COBE. In this Letter we consider a model of two inflatons with different masses,
, m1>m2 and study its effects on CMB of suppressing the primordial power spectrum P(k) at small k. Inflation is driven in this model firstly by the heavier inflaton φ1, then the lighter field φ2. But there is no interruption in between. We numerically calculate the scalar and tensor power spectra with mode by mode integrations, then fit the model to WMAP temperature correlations TT and the TE temperature-polarization spectra. Our results show that with m11014 GeV and m21013 GeV, this model solves the problems of flatness, etc. and the CMB quadrupole predicted can be much lower than the standard power-law ΛCDM model. 相似文献
To minimize instrumentally the induced systematic errors, cosmic microwave background (CMB) anisotropy experiments measure
temperature differences across the sky using pairs of horn antennas, temperature map is recovered from temperature difference
obtained in sky survey through a map-making procedure. To inspect and calibrate residual systematic errors in the recovered
temperature maps is important as most previous studies of cosmology are based on these maps. By analyzing pixel-ring coupling
and latitude dependence of CMB temperatures, we find notable systematic deviation from CMB Gaussianity in released Wilkinson
Microwave Anisotropy Probe (WMAP) maps. The detected deviation cannot be explained by the best-fit LCDM cosmological model
at a confidence level above 99% and cannot be ignored for a precision cosmology study.
Supported by the National Natural Science Foundation of China (Grant No. 10533020), the National Basic Research Program of
China (Grant No. 2009CB-824800), and the Directional Research Project of the Chinese Academy of Sciences (Grant No. KJCX2-YW-T03)
Contributed by LI TiPei 相似文献
Based on the postulate that photon propagation is governed by a dynamically broken SU(2) gauge symmetry (scale ∼10-4 eV) we make predictions for temperature offsets due to a low-temperature (a few times the present CMB temperature) spectral
anomaly at low frequencies. Temperature offsets are extracted from least-square fits of the anomalous black-body spectra to
their conventional counterparts. We discuss statistical errors, compare our results with those obtained from calibration data
of the FIRAS instrument, and point out that our predicted offsets are screened by experimental errors given the frequency
range used by FIRAS to perform their spectral fits. We also make contact with the WMAP observation by blueshifting their frequency
bands. Although our results hint towards a strong dynamical component in the CMB dipole and an explanation of low-l suppression,
it is important in view of its particle-physics implications that the above postulate be verified/falsified by an independent
low-temperature black-body precision experiment. 相似文献
This paper presents the application of the Szekeres Swiss Cheese model to the analysis of observations of the cosmic microwave
background (CMB) radiation. The impact of inhomogeneous matter distribution on the CMB observations is in most cases studied
within the linear perturbations of the Friedmann model. However, since the density contrast and the Weyl curvature within
the cosmic structures are large, this issue is worth studying using another approach. The Szekeres model is an inhomogeneous,
non-symmetrical and exact solution of the Einstein equations. In this model, light propagation and matter evolution can be
exactly calculated, without such approximations as small amplitude of the density contrast. This allows to examine in more
realistic manner the contribution of the light propagation effect to the measured CMB temperature fluctuations. The results
of such analysis show that small-scale, non-linear inhomogeneities induce, via Rees-Sciama effect, temperature fluctuations
of amplitude 10−7–10−5 on angular scale ϑ < 0.24° (ℓ > 750). This is still much smaller than the measured temperature fluctuations on this angular scale. However, local and uncompensated
inhomogeneities can induce temperature fluctuations of amplitude as large as 10−3, and thus can be responsible the low multipoles anomalies observed in the angular CMB power spectrum. 相似文献
The lowest multipole moments of the cosmic microwave background (CMB) are smaller than expected for a scale-invariant power spectrum. One possible explanation is a cutoff in the primordial power spectrum below a comoving scale of k(c) approximately equal to 5.0 x 10(-4) Mpc(-1). Such a cutoff would increase significantly the cross correlation between the large-angle CMB and cosmic-shear patterns. The cross correlation may be detectable at >2sigma which, combined with the low CMB moments, may tilt the balance between a 2sigma result and a firm detection of a large-scale power-spectrum cutoff. The cutoff also increases the large-angle cross correlation between the CMB and the low-redshift tracers of the mass distribution. 相似文献
We examine the effect of the thermal vacuum on the power spectrum of inflation by using the thermal field dynamics. We find that the thermal effect influences the CMB anisotropy at large length scale. After removing the divergence by using the holographic cutoff, we observe that the thermal vacuum explains well the observational CMB result at low multipoles. This shows that the temperature dependent factor should be considered in the study of power spectrum in inflation, especially at large length scale. 相似文献
Presuming that CMB photons are described by the deconfining phase of an SU(2) Yang‐Mills theory with the critical temperature for the deconfining‐preconfining phase transition matching the present CMB temperature K (SU(2)CMB), we investigate how CMB temperature T connects with the cosmological scale factor a in a Friedmann‐Lemaître‐Robertson‐Walker Universe. Owing to a violation of conformal scaling at late times, the tension between the (instantaneous) redshift of reionisation from CMB observation () and quasar spectra () is repealed. Also, we find that the redshift of CMB decoupling moves from to which questions ΛCDM cosmology at high redshifts. Adapting this model to the conventional physics of three flavours of massless cosmic neutrinos, we demonstrate inconsistency with the value Neff ~ 3.36 extracted from Planck data. Interactions between cosmic neutrinos and the CMB implies a common temperature T of (no longer separately conserved) CMB and neutrino fluids. Neff ~ 3.36 then entails a universal, temperature induced cosmic neutrino mass with . Our above results on zre and zdec, derived from SU(2)CMB alone, are essentially unaffected when including such a neutrino sector.
For the first time, measurements of the cosmic microwave background radiation (CMB) alone favor cosmologies with w = -1 dark energy over models without dark energy at a 3.2-sigma level. We demonstrate this by combining the CMB lensing deflection power spectrum from the Atacama Cosmology Telescope with temperature and polarization power spectra from the Wilkinson Microwave Anisotropy Probe. The lensing data break the geometric degeneracy of different cosmological models with similar CMB temperature power spectra. Our CMB-only measurement of the dark energy density Ω(Λ) confirms other measurements from supernovae, galaxy clusters, and baryon acoustic oscillations, and demonstrates the power of CMB lensing as a new cosmological tool. 相似文献
According to inflationary cosmology, the CMB anisotropy gives an opportunity to test predictions of new physics hypotheses. The initial state of quantum fluctuations is one of the important options at high energy scale, as it can affect observables such as the CMB power spectrum. In this study a quasi-de Sitter inflationary background with approximate de Sitter mode function built over the Bunch-Davies mode is applied to investigate the scale-dependency of the CMB anisotropy. The recent Planck constraint on spectral index motivated us to examine the effect of a new excited mode function(instead of pure de Sitter mode) on the CMB anisotropy at large angular scales. In so doing, it is found that the angular scale-invariance in the CMB temperature fluctuations is broken and in the limit 200 a tiny deviation appears. Also, it is shown that the power spectrum of CMB anisotropy is dependent on a free parameter with mass dimension H M* Mp and on the slow-roll parameter. 相似文献
We propose a new technique for high-accuracy reconstruction of the cosmic microwave background (CMB) anisotropy from observations contaminated by unresolved extragalactic point sources and pixel noise. The fundamental difference of this technique from the methods suggested before consists in reconstructing the CMB temperature fluctuations in regions contaminated by point sources with allowance for a priori information on the boundedness and spherical symmetry of the spatial power spectrum of the CMB anisotropy, which obeys the Gaussian statistics. The problems of deconvolving the initial maps, localizing point sources, and interpolating the CMB values in the holes are solved by using effective modifications of the well-known maximum entropy method. The results of simulations demonstrate the possibility of achieving the highest accuracy. 相似文献
A digitalized temperature map is recovered from the first light sky survey image published by the Planck team, from which an angular power spectrum of the cosmic microwave background (CMB) is derived. The amplitudes of the low multipoles (low-l) measured from the preliminary Planck power spectrum are significantly lower than those reported by the WMAP team. Possible systematical effects are far from enough to explain the observed low-l differences. 相似文献
The apparent low power in the cosmic microwave background (CMB) temperature anisotropy power spectrum derived from the Wilkinson Microwave Anisotropy Probe motivated us to consider the possibility of a nontrivial topology. We focus on simple spherical multiconnected manifolds and discuss their implications for the CMB in terms of the power spectrum, maps, and the correlation matrix. We perform a Bayesian model comparison against the fiducial best-fit cold dark matter model with a cosmological constant based both on the power spectrum and the correlation matrix to assess their statistical significance. We find that the first-year power spectrum shows a slight preference for the truncated cube space, but the three-year data show no evidence for any of these spaces. 相似文献
We investigate the effect of variation in the value of the fine-structure constant (alpha) at high redshifts (recombination > z > 30) on the absorption of the cosmic microwave background (CMB) at 21 cm hyperfine transition of the neutral atomic hydrogen. We find that the 21 cm signal is very sensitive to the variations in alpha and it is so far the only probe of the fine-structure constant in this redshift range. A change in the value of alpha by 1% changes the mean brightness temperature decrement of the CMB due to 21 cm absorption by >5% over the redshift range z < 50. There is an effect of similar magnitude on the amplitude of the fluctuations in the brightness temperature. The redshift of maximum absorption also changes by approximately 5%. 相似文献
A theory of Coherent Magnetic Breakdown (CMB) is presented here. CMB is observed at low temperatures in pure metallic samples. Different phenomena are being considered in conditions of MB: high frequency phenomena, sound absorption etc. 相似文献
Besides the Hubble expansion of the universe, the main evidence in favor of the big-bang theory was the discovery, by Penzias
and Wilson, of the cosmic microwave background (hereafter CMB) radiation. In 1990, the COBE satellite (Cosmic Background Explorer)
revealed an accurate black-body behavior with a temperature around 2.7 K. Although the microwave background is very smooth,
the COBE satellite did detect small variations—at the level of one part in 100 000—in the temperature of the CMB from place
to place in the sky. These ripples are caused by acoustic oscillations in the primordial plasma. While COBE was only sensitive
to long-wavelength waves, the Wilkinson Microwave Anisotropy Probe (WMAP)—with its much higher resolution—reveals that the
CMB temperature variations follow the distinctive pattern predicted by cosmological theory. Moreover, the existence of the
microwave background allows cosmologists to deduce the conditions present in the early stages of the big bang and, in particular,
helps to account for the chemistry of the universe. This report summarizes the latest measurements and studies of the CMB
with the new calculations about the formation of primordial molecules. The PLANCK mission—planned to be launched in 2009—is
also presented. 相似文献
One of the main challenges facing upcoming Cosmic Microwave Background (CMB) experiments aiming at measuring temperature anisotropies with great accuracy will be to assess the contamination of CMB measurements by galactic and extragalactic foregrounds. On the extragalactic side, confusion noise from extragalactic sources hampers the detection of intrinsic CMB anisotropies at small angular scales. Secondary CMB anisotropies must also be carefully accounted for in order to isolate the primordial fluctuations. We present in this article a brief overview of the extragalactic contributions to the CMB. The galactic foregrounds are discussed elsewhere (Giard and Lagache, this issue). To cite this article: G. Lagache, N. Aghanim, C. R. Physique 4 (2003).相似文献
The thermal evolution of the cosmic gas decoupled from that of the cosmic microwave background (CMB) at a redshift z approximately 200. Afterwards and before the first stars had formed, the cosmic neutral hydrogen absorbed the CMB flux at its resonant 21 cm spin-flip transition. We calculate the evolution of the spin temperature for this transition and the resulting anisotropies that are imprinted on the CMB sky due to linear density fluctuations during this epoch. These anisotropies, at an observed wavelength of 10.56[(1+z)/50] m, contain an amount of information that is orders of magnitude larger than any other cosmological probe. 相似文献