COBE satellite

The development of new low-temperature detection technology and the launch of the Cosmic Background Explorer (COBE) satellite by NASA in 1989 helped to resolve this problem. The results from these observations were amazing - an almost perfect black body curve (Figure 2.3) with a black body temperature of 2.725 0.002 K and a maximum wavelength of the radiation at kmax = 1.05 mm. 

FIGURE 1.9 The representation of intensity of spectral energy density per unit wavelength in the micro-waves domain, for the residual temperature of the Universe, about 2.74K, as had been recorded by the COBE satellite in 1989 data assumed and processed from Mather et al. (1990) and further adapted from HyperPhysics (2010) and Putz (2010). 

Amplitudes of density fluctuations at different wavelengths follow independent Gaussian (also called normal) statistics (see Sect. 9.3.6, Chap. 9, Vol. 1), and their mean spectral power is distributed in an almost scale-invariant manner, described above. The absolute normalization was determined by the COBE satellite to be 1 part in 100,000. Their evolution can be analyzed initially with the help of the linearized gravitational equations. The classical analysis, originally performed by Jeans (1902), leads to the conclusion that fluctuations above the Jeans-scale are unstable and they are at the origin of the formation of the oldest structures (for a modern textbook on the subject, see Peacock 1999). 

The COBE Satellite and Very Precise Measurements That Illuminate Our Cosmic Past... 

In 1989, the Cosmic Background Explorer (COBE) satellite was developed by NASA s Goddard Space Flight Center to measure the background radiation more precisely. The COBE satellite determined that the backgroimd radiation corresponded to a universe with a temperature of 2.735 K. (Notice the difference in significant figures from the previous measurement.) It went on to measure tiny... 

A The COBE Satellite, launched in 1989 to measure background radiation. Background radiation is a remnant of the Big Bang—the expansion that is believed to have formed the universe. 

J.C. Mather et al., A preliminary measurement of the cosmic microwave background spectrum by the COsmic Background Explorer (COBE) satellite. ApJ 354, L37-L40 (1990)... 

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. 

On the last three decades, several space experiments with parts at very low temperatures have been flown. Among these, we mention IRAS (Infrared Astronomical Satellite) launched in 1983 (see Fig. 14.1), COBE (Cosmic Background Explorer) launched in 1989, ISO (Infrared Space Observatory) launched in 1995 and Astro-E (X-ray Observatory), launched in 2000 with instrumentation at 65 mK [35], Some cryogenic space missions are in the preparation or in final phase in Europe, USA and Japan. For example, ESA is going to fly Planck (for the mapping of the cosmic background radiation) and Herschel (called before FIRST Far Infrared and Submillimetre Telescope ) [36], These missions will carry experiments at 0.1 and 0.3 K respectively. 

The WMAP satellite, launched on 30 June 2001, released it first year results on 11 Feb 2003. Simultaneously the mission was renamed the Wilkinson Microwave Anisotropy Probe to honor the late David T. Wilkinson who was a key member of both the COBE and the WMAP teams until his death in September... 

COBE Cosmic Background Explorer an orbiting satellite launched in November 1989 for cosmological research. In 1992, statistical studies of measurements on the microwave bacl round radiation indicated the presence of weak temperature fluctuations thought to be imprints of quantum fluctuations in the early universe. See alsoVIMAP. 

Remarkably, for the temperature values around T = 3K there are obtained wavelength in order size of micro-waves (millimeters) X = [10" /w] = rnm which corresponds to the remnant background radiation of the Universe, systematically detected by the research satellite COBE (The Cosmic Backgroimd Explorer), launched in 1989, Figure 1.9. 

The first quantitative evidence for the temperature anisotropy of CMBR was provided by the COBE (Cosmic Background Explorer) satellite in 1992. The angular resolution of its detectors was 7°. This enabled the collaboration to determine the first 20 multipole moments of the fluctuating part of CMBR beyond its isotropic component. It has been established that the degree of anisotropy of CMBR is one part in one hundred thousand (10 ). There are two questions of extreme importance related to this anisotropy ... 

Following the success of the COBE mission several more refined (ground based and balloon) measurements of the CMBR fluctuations were performed between 1998 and 2001. An angular resolution of about 1° has been achieved, which was further refined to the arc-minute level by the satellite mission Wilkinson Microwave Anisotropy Probe (WMAP). The combined efforts of these investigations allowed the determination of the multipole projection of CMBR on the sky up to angular moments I = 2,000. The fluctuation information extracted... 

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