Low-frequency measurements of the cosmic background radiation spectrum

Smoot, George F.; Amici, Giovanni De; Friedman, S. D.; Witebsky, C.; Sironi, G.; Bonelli, G.; Mandolesi, N.; Cortiglioni, S.; Morigi, G.; Partridge, R. B.; Danese, L.; Zotti, G. de

doi:10.1086/184451

Cited by 65 publications

(20 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Moreover, between 1 and 0.5 GHz the large dispersion of the error bars assigned by different observers to their results suggests that sometimes in the past not all the systematic effects were recognized. The frequency dependence of the accuracy of T sky is especially evident in coordinated experiments like the multifrequency observations made by the White Mountain Collaboration (Smoot et al 1985), the South Pole Collaboration , and by ARCADE ( Kogut et al 2004). These experiments cover the frequency interval 2Y100 GHz and approach the frequency region close to 1 GHz where neither T CMB nor T Gal is dominant and the models of T Gal and T UERS are insufficient to extract with the desired accuracy the cosmological signal.…”

Section: Absolute Measurements Of Temperaturementioning

confidence: 99%

TRIS. I. Absolute Measurements of the Sky Brightness Temperature at 0.6, 0.82, and 2.5 GHz

Zannoni

Tartari

Gervasi

et al. 2008

Astrophysical Journal

Self Cite

View full text Add to dashboard Cite

At frequencies close to 1 GHz the sky diffuse radiation is a superposition of radiation of Galactic origin, the 3 K relic or cosmic microwave background radiation, and the signal produced by unresolved extragalactic sources. Because of their different origin and space distribution, the relative importance of the three components varies with frequency and depends on the direction of observation. With the aim of disentangling the components we built TRIS, a system of three radiometers, and studied the temperature of the sky at ¼ 0:6, 0.82, and 2.5 GHz using geometrically scaled antennas with identical beams (HPBW ¼ 18; 23 ). Observations included drift scans along a circle at constant declination ¼ þ42, which provided the dependence of the sky signal on the right ascension, and absolute measurement of the sky temperature at selected points along the same scan circle. TRIS was installed at Campo Imperatore (latitude ¼ 42 26 0 north, longitude ¼ 13 33 0 , elevation ¼ 2000 m a.s.l.) in central Italy, close to the Gran Sasso Laboratory.

show abstract

Section: Absolute Measurements Of Temperaturementioning

confidence: 99%

TRIS. I. Absolute Measurements of the Sky Brightness Temperature at 0.6, 0.82, and 2.5 GHz

Zannoni

Tartari

Gervasi

et al. 2008

Astrophysical Journal

Self Cite

View full text Add to dashboard Cite

show abstract

“…The first reliable detection of a dipole moment was that reported by Corey and Wilkinson (1976), who employed a radiometer operating at A = 1.5 cm carried aloft by a balloon (unfortunately the details of this experiment are not readily available, but see Cheng et a1 (1979)). By the late 1970s, four groups had measured the dipole component to a much higher precision, using instruments carried aloft by balloons or high-flying aircraft (Muehlner 1976, Smoot et al 1977, Fabbri et a1 1980a, Boughn et a1 1981. Two of these groups also reported evidence for a quadrupole component of -a the dipole amplitude (but see below).…”

Section: Resultsmentioning

confidence: 99%

Effects of Methyl Silsesquioxane Electron-Beam Curing on Device Characteristics of Logic and Four-Transistor Static Random-Access Memory

Lin

Tung

Feng

1999

Jpn. J. Appl. Phys.

View full text Add to dashboard Cite

The cosmic background radiation is thermal radiation with a temperature of 2.75 K still present throughout the universe, a relic of its hot, big bang, initial phase. Detailed studies of this radiation, and particularly its angular variations, can provide information obtainable in no other way about the global geometry and expansion of the universe, about the distribution of mass near our Galaxy, and about the process of galaxy formation. This review treats searches for such angular variations and the consequences of the resulting measurements of, or upper limits on, variations in the cosmic background radiation.The only unambiguously detected angular variation is the dipole component of the radiation, believed to arise from a Doppler shift due to the motion of the Earth; the inferred velocity of the Earth relative to the background is -350 km s-'. Searches for a quadrupole component have found none, with upper limits on the fractional variation, A T / T , of a few times IO-'. The absence of a significant quadrupole moment allows us to reject many models for the universe which include anisotropic expansion or shear. These constraints are reinforced by upper limits on the linear polarisation of the cosmic background radiation.Searches for smaller scale variations, at angles from arcseconds to degrees, have thus far failed to find any. At some angular scales, upper limits on temperature fluctuations have now reached a level of a few times Reviewed here are both the observational methods employed in such searches and some of the sources of statistical and systematic errors encountered. Several consequences of the upper limits on fluctuations in the radiation are examined. Among these are constraints on models for the formation of large astronomical systems like galaxies, and the support these observations lend to models for the very early expansion of the universe which arise from new theories in particle physics.An outline of big bang cosmology is contained in an appendix for readers unfamiliar with the nomenclature of cosmology.

show abstract

“…With the exception of FIRAS ( [2,25]) and the Gush experiment ( [26]) which cover continuously extended frequency intervals, the majority of the values of T (ν) in literature are discrete, isolated, single frequency points, obtained independently by different observers, at different sites, using different radiometers. Only after a few years of observations groups of observers began to coordinate their efforts, measuring the absolute temperature of the same region of sky, at different frequencies, from the same site using similar systems ( [18,[22][23][24] and a common reference source. This way of doing reduced the weight of systematic effects and improved the accuracy of the final results.…”

Section: Search Of Distortions By Absolute Measurements Of T (ν)mentioning

confidence: 99%

Challenges and prospects for better measurements of the CMB intensity spectrum

Sironi

2017

J. Cosmol. Astropart. Phys.

View full text Add to dashboard Cite

Abstract. Spectral distortions of the Cosmic Microwave Background (CMB) offer the possibility of probing processes which occurred during the evolution of our Universe going back up to Z 10 7 . Unfortunately all the attempts so far carried out for detecting distortions failed. All of them were based on comparisons among absolute measurements of the CMB temperature at different frequencies. We suggest a different approach: measurements of the frequency derivative of the CMB temperature over large frequency intervals instead of observations of the absolute temperature at few, well separated, frequencies as frequently done in the past, and, direct measurements of the foregrounds which hinder observations, at the same site and with the same radiometer prepared for the search of CMB distortions. We discuss therefore the perspectives of new observations in the next years from the ground, at very special sites, or in space as independent missions or part of other CMB projects

show abstract

Low-frequency measurements of the cosmic background radiation spectrum

Cited by 65 publications

References 0 publications

TRIS. I. Absolute Measurements of the Sky Brightness Temperature at 0.6, 0.82, and 2.5 GHz

TRIS. I. Absolute Measurements of the Sky Brightness Temperature at 0.6, 0.82, and 2.5 GHz

Effects of Methyl Silsesquioxane Electron-Beam Curing on Device Characteristics of Logic and Four-Transistor Static Random-Access Memory

Challenges and prospects for better measurements of the CMB intensity spectrum

Contact Info

Product

Resources

About