Band Power Spectra in the [ITAL]COBE[/ITAL] DMR Four-Year Anisotropy Maps

Hinshaw, G.; Banday, A. J.; Bennett, C. L.; Górski, K. M.; Kogut, A.; Smoot, George F.; Wright, E. L.

doi:10.1086/310074

Cited by 103 publications

(92 citation statements)

References 19 publications

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“…428 K. This is consistent with the value predicted by a power-law "t to the power spectrum yields a quadrupole normalization of: Q U.1 "15.3> \ K [47,36]. (5) The power spectrum of large angular scale CMB measurements is consistent with an n"1 power-law [33,36,88].…”

Section: Summary Of 4-year Cobe Dmr Cmb Measurementssupporting

confidence: 79%

“…The combined dust and free}free emission contribute 10$4 K rms at both 53 and 90 GHz, well below the 30 K cosmic signal. These Galactic signal analyses are consistent with the fact that the "tted cosmological parameters are nearly una!ected by removal of modeled Galactic signals [33,36] with the notable exception of the quadrupole, which has signi"cant Galactic contamination [47]. A search by Banday et al [4] "nds no evidence for signi"cant extragalactic contamination of the DMR maps.…”

Section: The Cobe Dmr Instruments and Data Analysissupporting

confidence: 64%

“…(5) The power spectrum of large angular scale CMB measurements is consistent with an n"1 power-law [33,36,88]. If the e!ects of a standard cold dark matter model are included, COBE DMR should "nd n +1.1 for a n"1 universe.…”

Section: Summary Of 4-year Cobe Dmr Cmb Measurementsmentioning

confidence: 91%

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CMB anisotropy experiments

Smoot

2000

Physics Reports

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Anisotropies in the cosmic microwave background (CMB) encode information about the evolution and development of the universe. Quality observations of CMB anisotropies can provide a very strong test of cosmological models and provide high precision determination of major cosmological parameters. This paper provides a review of the COBE DMR results, the current status of the measurements of the CMB anisotropy power spectrum and then focuses current and future programs including both suborbital observations and the two selected satellite missions: the NASA MidEX mission MAP and the ESA M3 mission Max Planck Surveyor. This review includes both a description of the experimental programs and the expected quality level of results.

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Section: Summary Of 4-year Cobe Dmr Cmb Measurementssupporting

confidence: 79%

Section: The Cobe Dmr Instruments and Data Analysissupporting

confidence: 64%

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CMB anisotropy experiments

Smoot

2000

Physics Reports

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“…Curiously, the COBE data suggests a suppression, and perhaps even a bump-like feature in the low-ℓ multipoles. [6,7] The data is not decisive because the cosmic variance and experimental error are large for the low-ℓ multipoles. Forthcoming data from the MAP and Planck satellite experiments may lead to some improvement.…”

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confidence: 99%

Effects of the sound speed of quintessence on the microwave background and large scale structure

2003

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We consider how quintessence models in which the sound speed differs from the speed of light and varies with time affect the cosmic microwave background and the fluctuation power spectrum. Significant modifications occur on length scales related to the Hubble radius during epochs in which the sound speed is near zero and the quintessence contributes a non-negligible fraction of the total energy density. For the microwave background, we find that the usual enhancement of the lowest multipole moments by the integrated Sachs-Wolfe effect can be modified, resulting in suppression or bumps instead. Also, the sound speed can produce oscillations and other effects at wavenumbers k > 10 −2 h/Mpc in the fluctuation power spectrum.PACS numbers: PACS number(s): 98.80. 98.70.Vc, One of the greatest challenges in cosmology today is to identify the nature of the dark energy component that comprises most of the energy density of the universe and that is causing the expansion of the universe to accelerate.[1] Two candidates are a cosmological constant (or vacuum density) and quintessence,[2] a dynamical energy component with negative pressure. Distinguishing the two is important for cosmology in order to refine our knowledge of the composition of the universe and to trace more accurately its evolution. It is even more important for fundamental physics since it informs us how we must modify unified theories to incorporate dark energy.One way to distinguish whether the dark energy is due to a cosmological constant or quintessence is to measure the equation of state, w, the ratio of the pressure p to the energy density ρ. A cosmological constant always has w = −1 whereas a scalar field generally has a w(z) that differs from unity and varies with red shift z. Through measurements of supernovae, large-scale structure and the cosmic microwave background (cmb) anisotropy, the equation of state may be determined accurately enough in the next few years to find out whether w is different from −1 or not.A second way to distinguish the nature of dark energy is to measure its sound speed to determine if it is different from unity. The sound speed can be detected because it affects the perturbations in the quintessence energy distribution. This approach is less generic because the sound speed in many models of quintessence in the literature is equal to unity (the speed of light), e.g., models in which quintessence consists of a scalar field (φ) with canonical kinetic energy density (X ≡ 1 2 (∂ µ φ)2 ) and a positive potential energy density (V (φ)). However, in general, the sound speed can differ from unity and vary with time. Detecting these effects is an independent way of showing that dark energy does not consist of a cosmological constant.An important motivating example is k -essence. [3] In these models, the k -essence undergoes two transitions in its behavior, one beginning at the onset of matterdomination and a second when k -essence overtakes the matter density. During the radiation-dominated era, the k-essence energy tracks the rad...

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“…The requirement of a large non-baryonic dark matter component appears also substantiated by the CMB data analysis. After initial measurements at large angular scale by the COBE satellite [23], the BOOMERANG [24], MAXIMA [25], DASI [26], ARCHEOPS [27] and CBI [28] balloon and ground-based experiments have constrained the total cosmological density to be within ∼ 3% of the critical density. More recently, the WMAP satellite experiment [29] together with the SDSS and 2dF surveys [14] have further reduced the uncertainty on these cosmological parameters.…”

Section: Cosmological Constraintsmentioning

confidence: 99%

Dark Matter: Direct Detection

Chardin

2009

AIP Conference Proceedings

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Abstract. Solving the Dark Matter enigma represents one of the key objectives of contemporary physics. Recent astrophysical and cosmological measurements have unambiguously demonstrated that ordinary matter contributes to less than 5% of the energy budget of our Universe, and that the nature of the remaining 95% is unknown. Weakly Interacting Massive Particles (WIMPs) represent the best motivated candidate to fill the Dark Matter gap, and direct detection Dark Matter experiments have recently reached sensitivities allowing them to sample a first part of supersymmetric models compatible with accelerator constraints.Three cryogenic experiments currently provide the best sensitivity, by nearly one order of magnitude, to WIMP interactions. With systematic uncertainties far less severe than other present techniques, the next generation of cryogenic experiments promises two orders of magnitude increase in sensitivity over the next few years. The present results, perspectives and experimental strategies of the main direct detection experiments are presented. Challenges met by future ton-scale cryogenic experiments in deep underground sites, aiming at testing most of the SUSY parameter space, are critically discussed.The Dark Matter enigma was first formulated by Fritz Zwicky [1] in the early thirties. From observations of the velocity dispersion of eight galaxies in the Coma cluster, Zwicky found that the velocities of these galaxies were far too large to allow them to remain trapped in the cluster's gravitational well. Converting the observed velocity dispersion in terms of mass deficit, Zwicky concluded that visible stars only contribute 0.5% of the total mass present in the Coma cluster. Today, although the reevaluations of the distance scale and the Hubble parameter lead to a revised estimate of the missing mass factor, Zwicky's observations appear as one of the most astonishing and profound insights of modern physics.

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Band Power Spectra in the [ITAL]COBE[/ITAL] DMR Four-Year Anisotropy Maps

Cited by 103 publications

References 19 publications

CMB anisotropy experiments

CMB anisotropy experiments

Effects of the sound speed of quintessence on the microwave background and large scale structure

Dark Matter: Direct Detection

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