Cosmic microwave background CMB

We shall now describe an infrared bolometer operating at 0.3 K, built by Lange et al. in 1992 [80], We chose this example because such composite bolometer can be easily described from a cryogenic point of view, whereas the analysis of more recent devices would be quite complicated. Nevertheless the bolometer performances are very good, the NEP being less than 10-16 W/(Hz)1/2 and the time constant r = 11ms. It was used for the measurement of the cosmic microwave background (CMB) in an experiment on board of a stratospheric balloon [81]. 

The main goal of the Planck instrument is to improve the accuracy of the measurement of the cosmic microwave background (CMB), in order to extract cosmological parameters that remain poorly constrained after the results of WMAP (Wilkinson microwave anisotropy probe) and of the best ground-based experiments. The basic idea of HFI-Planck is to use all the information contained in the CMB radiation, i.e. to perform a radiometric measurement limited by the quantum fluctuations of the CMB radiation itself. In these conditions, the accuracy is only limited by the number of detectors and by the duration of the observation. 

The Cosmic Microwave Background (CMB) was first seen via its effect on the interstellar CN radical (Adams, 1941) but the significance of the this datum was not realized until after 1965 (Thaddeus, 1972 Kaiser and Wright, 1990). In fact, Herzberg, 1950 calculated a 2.3 K excitation temperature for the CN transition and said it had of course only a very restricted meaning. Later work by Roth et al., 1993 obtained a value for T0 = 2.729iJj Jjif i K at the CN 1-0 wavelength of 2.64 mm which is still remarkably accurate. 

Shortly after the Cosmic Microwave Background (CMB) was discovered, the first anisotropy in the CMB was seen the dipole pattern due to the motion of the observer relative to the rest of the Universe (Conklin, 1969). After confirmation by Henry, 1971 and by Corey and Wilkinson, 1976 the fourth discovery of the dipole (Smoot et al., 1977) showed a very definite cosine pattern as expected for a Doppler effect, and placed an upper limit on any further variations in Tcmb Further improvements in the measurement of the dipole anisotropy were made by the Differential Microwave Radiometers (DMR) experiment on COBE (Bennett et al., 1996 and by the Wilkinson Microwave... 

Observations with the Cosmic Background Explorer (COBE) have shown that, to a precision of better than 10 , the cosmic microwave background (CMB) is thermal, with a temperature of 2.73 K (Mather et al., 1994). 

We should acknowledge that there are two basic possibilities of variations of constants. One is a result of certain violation of LPl, while the other is an observational effect of the interaction with environment, such as the bath of Cosmic Microwave Background (CMB) radiation of photons, neutrinos, gravitons. Dark Matter (DM), matter, etc. 

Fig. 1.1 Schematic Spectral Eneigy Distributions (SED) of the most important (by intensity) backgrounds in the Universe, and their approximate brightness in nW m sr written in the boxes. Erom right to left the Cosmic Microwave Background (CMB), the Cosmic Infrared Background (CIB) tmd the Cosmic Optical Background (COB) [Credit Dole et al. A A, 451(2), 417-429,2006, reproduced with permission ESO]...

At the Detector Noise Moduie, the Noise Equivalent Power (NEP) associated to the detectors and the 1 // noise are calculated. In parallel, with the physical properties of the system defined, the Background Power Module calculates the background power noise due to the instmment and the Cosmic Microwave Background (CMB), Cosmic Infrared Background (CIB) and Zodiacal Light. 

Extremely low frequency region, 10 -10 Hz The gravitational waves produce quadrupole anisotropies in the cosmic microwave background (CMB) radiation. The wave spectrum is described by the fraction of energy density g f) (in a bandwidth /) needed to close the universe. From observations of the COBE satellite < 10 ° at 10 Hz. 

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