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In this paper, we estimate the Cosmic Microwave Background (CMB) temperature using the data of the monopole spectrum from the Cosmic Background Explorer/ Far-Infrared Absolute Spectrophotometer (COBE/FIRAS). Utilising the idea of straight-line fitting, we obtain the temperature and chemical potential. The temperature of the CMB is found to be (2.725007 ± 0.000024) K (only statistical error) by using the monopole spectrum. Handling the data of the monopole spectrum the chemical potential is obtained as (-1.1 ± 3.4) × 10 –5 with an upper bound |µ| < 5.7 × 10 –5  (95% confidence level). The amplitude of the CMB dipole is found to be, T amp  = (3.47 ± 0.11) mK. We estimate an upper limit for the rms value of the fluctuation in chemical potential as Δµ < 1.2 × 10 –4 (95% confidence level). The upper limit of y- distortion is calculated as y < 1.0 × 10 –4 (95% confidence level).

The cosmic microwave background (CMB) radiation, the relic afterglow of the Big Bang, has become one of the most useful and precise tools in modern precision cosmology. In this article, we employ Tsallis non-extensive statistical framework to calculate the cosmic microwave background (CMB) temperature and its probability distribution by utilising a recently proposed blackbody radiation inversion (BRI) technique and the cosmic background explorer/ far infrared absolute spectrophotometer (COBE/FIRAS) dataset. Here, we have used the best-fit values of q = 0.99888 ± 0.00016 and q = 1.00012 ± 0.00001, obtained by fitting COBE/FIRAS data with two different versions of non-extensive models. We compare the results with the more conventional extensive statistical analysis i.e. for q = 1.

We report near-infrared polarization of the zodiacal light (ZL) measured from space by the Diffuse Infrared Background Experiment (DIRBE) on board the Cosmic Background Explorer in photometric bands centered at 1.25, 2.2, and 3.5 \\(\\mu\\)m. To constrain the physical properties of interplanetary dust (IPD), we use DIRBE Weekly Sky Maps to investigate the solar elongation (\\(\\epsilon\\)), ecliptic latitude (\\(\\beta\\)), and wavelength (\\(\\lambda\\)) dependence of ZL polarization. We find that the polarization of the ZL varies as a function of \\(\\epsilon\\) and \\(\\beta\\), consistent with observed polarization at \\(\\lambda\\) = 550 nm. While the polarization dependence with wavelength at \\((\\epsilon\\), \\(\\beta)=(90^{\\circ}\\), \\(0^{\\circ})\\) is modest (increasing from 17.7 \\(\\pm\\) 0.2% at 1.25 \\(\\mu\\)m to 21.0 \\(\\pm\\) 0.3% at 3.5 \\(\\mu\\)m), the variation is more pronounced at the North Ecliptic Pole (23.1 \\(\\pm\\) 1.6, 35.1 \\(\\pm\\) 2.0 and 39.3 \\(\\pm\\) 2.1% at 1.25, 2.2 and 3.5 \\(\\mu\\)m, respectively). The variation of ZL polarization with wavelength is not explained by either Rayleigh scattering or by absorptive particles larger than 10 \\(\\mu\\)m.

We report observation of isotropic interplanetary dust (IPD) by analyzing the infrared (IR) maps of Diffuse Infrared Background Experiment (DIRBE) onboard the Cosmic Background Explorer (COBE) spacecraft. To search for the isotropic IPD, we perform new analysis in terms of solar elongation angle (\\(\\epsilon\\)), because we expect zodiacal light (ZL) intensity from the isotropic IPD to decrease as a function of \\(\\epsilon\\). We use the DIRBE weekly-averaged maps covering \\(64^\\circ \\lesssim \\epsilon \\lesssim 124^\\circ\\) and inspect the \\(\\epsilon\\)-dependence of residual intensity after subtracting conventional ZL components. We find the \\(\\epsilon\\)-dependence of the residuals, indicating the presence of the isotropic IPD. However, the mid-IR \\(\\epsilon\\)-dependence is different from that of the isotropic IPD model at \\(\\epsilon \\gtrsim 90^\\circ\\), where the residual intensity increases as a function of \\(\\epsilon\\). To explain the observed \\(\\epsilon\\)-dependence, we assume a spheroidal IPD cloud showing higher density further away from the sun. We estimate intensity of the near-IR extragalactic background light (EBL) by subtracting the spheroidal component, assuming the spectral energy distribution from the residual brightness at \\(12\\,{\\rm \\mu m}\\). The EBL intensity is derived as \\(45_{-8}^{+11}\\), \\(21_{-4}^{+3}\\), and \\(15\\pm3\\,{\\rm nWm^{-2}sr^{-1}}\\) at \\(1.25\\), \\(2.2\\), and \\(3.5\\,{\\rm \\mu m}\\), respectively. The EBL is still a few times larger than integrated light of normal galaxies, suggesting existence of unaccounted extragalactic sources.

This interesting book reviews WMAP's main results (2003) and discusses in detail how the accurate qualitative results for the “age” of the universe and the Hubble constant were anticipated in an article published five years before in Acta Cosmologica, Krakow. In the final chapter on “Cosmic Numbers”, it is shown that, as a result of the coincidence at decoupling time between atom formation and matter/radiation equality, a reasonable cosmic justification for the mass ratio of protons and electrons is obtained.

This work presents a summary of major cosmological results from the COBE (Cosmic Background Explorer) satellite mission. The results include a precise measurement of the Cosmic Microwave Background (CMB) radiation intensity, discovery and maps of the CMB anisotropy, large scale observations of the CMB polarization, and the detection and measurement of the diffuse infrared background. This summary was occassioned by and is part of the proceedings for the 3K Cosmology Conference held at Rome in October 1998.

Small departures from a homogeneous isotropic spacetime create observable features in the large-scale anisotropy of the cosmic microwave background. We cross-correlate the maps of the cosmic microwave background anisotropy from the Cosmic Background Explorer (COBE) Differential Microwave Radiometers (DMR) 4-year data set with template maps from Bianchi VII_h cosmological models to limit global rotation or shear in the early universe. On the largest scales, spacetime is well described by the Friedmann-Robertson-Walker metric, with departures from isotropy about each spatial point limited to shear sigma/H_0 < 10^{-9} and rotation omega/H_0 < 6 x 10^{-8} for 0.1 < Omega_0 < 1.

We have refined the analysis of the data from the FIRAS (Far InfraRed Absolute Spectrophotometer) on board the COBE (COsmic Background Explorer). The FIRAS measures the difference between the cosmic microwave background and a precise blackbody spectrum. We find new tighter upper limits on general deviations from a blackbody spectrum. The RMS deviations are less than 50 parts per million of the peak of the CMBR. For the Comptonization and chemical potential we find \\(|y| < 15\\times10^{-6}\\) and \\(|\\mu| < 9\\times10^{-5}\\) (95\\% CL). There are also refinements in the absolute temperature, 2.728 \\(\\pm\\) 0.004 K (95\\% CL), and dipole direction, \\((\\ell,b)=(264.14^\\circ\\pm0.30, 48.26^\\circ\\pm0.30)\\) (95\\% CL), and amplitude, \\(3.372 \\pm 0.007\\) mK (95\\% CL). All of these results agree with our previous publications.

\"It has observed the universe as it was at its birth,\" Dr. [John Mather] said. \"It's done everything we asked it to do, and it's a proud day for us to declare our flight operations complete.\" A second instrument found long-sought temperature variations in the radiation that existed 300,000 years after the Big Bang. The fluctuations were faint, only about one 30-millionth of a degree warmer or cooler than the rest of the sky. The cold spots were denser matter that could condense into huge clouds of galaxies; the hot spots were thinner regions that eventually contained no galaxies, NASA said.

The Differential Microwave Radiometers (DMR) instrument aboard the Cosmic Background Explorer (COBE) has mapped the full microwave sky to mean sensitivity 26 uK per 7 deg field of view. The absolute calibration is determined to 0.7% with drifts smaller than 0.2% per year. We have analyzed both the raw differential data and the pixelized sky maps for evidence of contaminating sources such as solar system foregrounds, instrumental susceptibilities, and artifacts from data recovery and processing. Most systematic effects couple only weakly to the sky maps. The largest uncertainties in the maps result from the instrument susceptibility to the Earth's magnetic field, microwave emission from the Earth, and upper limits to potential effects at the spacecraft spin period. Systematic effects in the maps are small compared to either the noise or the celestial signal: the 95% confidence upper limit for the pixel-pixel rms from all identified systematics is less than 6 uK in the worst channel. A power spectrum analysis of the (A-B)/2 difference maps shows no evidence for additional undetected systematic effects.