First Intrinsic Anisotropy Observations with the Cosmic Background Imager

Padin, S.; Cartwright, J. K.; Mason, B. S.; Pearson, T. J.; Readhead, A. C. S.; Shepherd, M. C.; Sievers, Jonathan; Udomprasert, P. S.; Holzapfel, W. L.; Myers, S. T.; Carlstrom, J. E.; Leitch, E. M.; Joy, M.; Bronfman, L.; May, J.

doi:10.1086/319142

Cited by 153 publications

(130 citation statements)

References 29 publications

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“…2) strongly favors a flat universe with a non-zero value of cosmological constant, with preferred values Ω m ≈ 0. 28, Ω Λ ≈ 0.72 Fig. 2.…”

Section: Cosmological Constraintsmentioning

confidence: 92%

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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“…2) strongly favors a flat universe with a non-zero value of cosmological constant, with preferred values Ω m ≈ 0. 28, Ω Λ ≈ 0.72 Fig. 2.…”

Section: Cosmological Constraintsmentioning

confidence: 92%

Dark Matter: Direct Detection

Chardin

2009

AIP Conference Proceedings

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“…3. This effect has been used previously to constrain N ν using data from the best present day experiments [41][42][43][44], namely Boomerang [45], Maxima [46], CBI [47] and DASI [48]. Unfortunately the data is not yet of sufficient accuracy to yield constraints anywhere near as strong as BBN.…”

Section: Cosmological Neutrino Lepton Asymmetrymentioning

confidence: 99%

Neutrino Physics From Cosmological Observations

Hannestad

2004

Beyond the Desert 2003

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We review the current status of neutrino cosmology, focusing mainly on the question of the absolute values of neutrino masses and the possibility of a cosmological neutrino lepton asymmetry. Neutrino massesThe absolute value of neutrino masses are very difficult to measure experimentally. On the other hand, mass differences between neutrino mass eigenstates, (m 1 , m 2 , m 3 ), can be measured in neutrino oscillation experiments. Observations of atmospheric neutrinos suggest a squared mass difference of δm 2 ≃ 3 × 10 −3 eV 2 [1,2]. While there are still several viable solutions to the solar neutrino problem the so-called large mixing angle solution gives by far the best fit with δm 2 ≃ 5×10 In the simplest case where neutrino masses are hierarchical these results suggest that m 1 ∼ 0, m 2 ∼ δm solar , and m 3 ∼ δm atmospheric . If the hierarchy is inverted [5-10] one instead finds m 3 ∼ 0, m 2 ∼ δm atmospheric , and m 1 ∼ δm atmospheric . However, it is also possible that neutrino masses are degenerate [11][12][13][14][15][16][17][18][19][20][21], m 1 ∼ m 2 ∼ m 3 ≫ δm atmospheric , in which case oscillation experiments are not useful for determining the absolute mass scale.Experiments which rely on kinematical effects of the neutrino mass offer the strongest probe of this overall mass scale. Tritium decay measurements have been able to put an upper limit on the electron neutrino mass of 2.2 eV (95% conf.) [22] (see also the contribution by Ch. Weinheimer in the present volume). However, cosmology at present yields an even stronger limit which is also based on the kinematics of neutrino mass.Neutrinos decouple at a temperature of 1-2 MeV in the early universe, shortly before electron-positron annihilation. Therefore their temperature is lower than the photon temperature by a factor (4/11) 1/3 . This again means that the total neutrino number density is related to the photon number density byMassive neutrinos with masses m ≫ T 0 ∼ 2.4 × 10 −4 eV are non-relativistic at present and therefore contribute to the cosmological matter density [23][24][25]]calculated for a present day photon temperature T 0 = 2.728K. Here, m ν = m 1 + m 2 + m 3 . However, because they are so light these neutrinos free stream on a scale of roughly k ≃ 0.03m eV Ω 1/2 [26][27][28]. Below this scale neutrino perturbations are completely erased and therefore the matter power spectrum is suppressed, roughly by ∆P/P ∼ −8Ω ν /Ω m [28].This power spectrum suppression allows for a determination of the neutrino mass from measurements of the matter power spectrum on large scales. This matter spectrum is related to the galaxy correlation spectrum measured in large scale structure (LSS) surveys via the bias parameter, b 2 ≡ P g (k)/P m (k). Such analyses have been performed several times before [29,30], most recently using data from the 2dF galaxy survey [31]. This investigation finds an upper limit of 1.8-2.2 eV for the sum of neutrino masses. However, this result is based on a relatively limited cosmological parameter space. For the same data and an ...

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“…According to observational data on the temperature variations in the cosmic microwave background (CMB) that became in public at that epoch (de Bernardis et al 2000;Jaffe et al 2001;Padin et al 2001;Stompor et al 2001;Netterfield et al 2002), now, we are quite confident that the Universe can be adequately described by a spatially flat Robertson-Walker (RW) cosmological model.…”

Section: Introductionmentioning

confidence: 99%

A conventional approach to the dark-energy concept

Kleidis

Spyrou

2011

A&A

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Motivated by results implying that the constituents of dark matter (DM) might be collisional, we consider a cosmological (toy-) model, in which the DM itself possesses some sort of thermodynamic properties. In this case, not only can the matter content of the Universe (the baryonic component, which is tightly gravitationally-bounded to the dark one, also being included) be treated as a classical gravitating fluid of positive pressure, but, together with all its other physical characteristics, the energy of this fluid's internal motions should be taken into account as a source of the universal gravitational field. In principle, this form of energy can compensate for the extra (dark) energy, needed to compromise spatial flatness, while the post-recombination Universe remains ever-decelerating. What is more interesting, is that, at the same time (i.e., in the context of the collisional-DM approach), the theoretical curve representing the distance modulus as a function of the cosmological redshift, μ(z), fits the Hubble diagram of a multi-used sample of supernova Ia events quite accurately. A cosmological model filled with collisional DM could accommodate the majority of the currently-available observational data (including, also, those from baryon acoustic oscillations), without the need for either any dark energy (DE) or the cosmological constant. However, as we demonstrate, this is not the case for someone who, although living in a Universe filled with self-interacting DM, insists on adopting the traditional, collisionless-DM approach. From the point of view of this observer, the cosmologically-distant light-emitting sources seem to lie farther (i.e., they appear to be dimmer) than expected, while the Universe appears to be either accelerating or decelerating, depending on the value of the cosmological redshift. This picture, which, nowadays, represents the common perception in observational cosmology, acquires a more conventional interpretation within the context of the collisional-DM approach.

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First Intrinsic Anisotropy Observations with the Cosmic Background Imager

Cited by 153 publications

References 29 publications

Dark Matter: Direct Detection

Dark Matter: Direct Detection

Neutrino Physics From Cosmological Observations

A conventional approach to the dark-energy concept

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