Perturbations of a Cosmological Model and Angular Variations of the Microwave Background

Sachs, Rainer K.; Wolfe, Arthur M.

doi:10.1086/148982

Cited by 1,729 publications

(1,543 citation statements)

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“…On large angular scales, a major contribution to CMB anisotropies comes from gravitational redshifts and blueshifts of photon energies (Sachs and Wolfe, 1967). In a universe with Ω tot = Ω m = 1, potential fluctuations δΦ ∼ G δM/R stay constant because (in linear perturbation theory) δM and R both grow in proportion to a(t).…”

Section: The Integrated Sachs-wolfe Effectmentioning

confidence: 99%

Observational probes of cosmic acceleration

et al. 2013

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The accelerating expansion of the universe is the most surprising cosmological discovery in many decades, implying that the universe is dominated by some form of "dark energy" with exotic physical properties, or that Einstein's theory of gravity breaks down on cosmological scales. The profound implications of cosmic acceleration have inspired ambitious efforts to understand its origin, with experiments that aim to measure the history of expansion and growth of structure with percent-level precision or higher. We review in detail the four most well established methods for making such measurements: Type Ia supernovae, baryon acoustic oscillations (BAO), weak gravitational lensing, and the abundance of galaxy clusters. We pay particular attention to the systematic uncertainties in these techniques and to strategies for controlling them at the level needed to exploit "Stage IV" dark energy facilities such as BigBOSS, LSST, Euclid, and WFIRST. We briefly review a number of other approaches including redshift-space distortions, the Alcock-Paczynski effect, and direct measurements of the Hubble constant H 0 . We present extensive forecasts for constraints on the dark energy equation of state and parameterized deviations from General Relativity, achievable with Stage III and Stage IV experimental programs that incorporate supernovae, BAO, weak lensing, and cosmic microwave background data. We also show the level of precision required for clusters or other methods to provide constraints competitive with those of these fiducial programs. We emphasize the value of a balanced program that employs several of the most powerful methods in combination, both to cross-check systematic uncertainties and to take advantage of complementary information. Surveys to probe cosmic acceleration produce data sets that support a wide range of scientific investigations, and they continue the longstanding astronomical tradition of mapping the universe in ever greater detail over ever larger scales.

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Section: The Integrated Sachs-wolfe Effectmentioning

confidence: 99%

Observational probes of cosmic acceleration

et al. 2013

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“…This coupling to Φ a (or its energy-density counterpart) turned out to be essential for an adequate description of the matter power spectrum [43,44]. Generally speaking, for the behaviour of the gravitational potential such a coupling causes deviations from the ΛCDM model which are especially relevant from the viewpoint of the integrated Sachs-Wolfe (ISW) effect [50], where an integration ofΦ up to k → ∞ has to be performed. Numerical solutions of Eq.…”

Section: Eckart's Casementioning

confidence: 99%

Bulk viscous cosmology with causal transport theory

Piattella

Fabris

Zimdahl

2011

J. Cosmol. Astropart. Phys.

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Abstract. We consider cosmological scenarios originating from a single imperfect fluid with bulk viscosity and apply Eckart's and both the full and the truncated Müller-Israel-Stewart's theories as descriptions of the non-equilibrium processes. Our principal objective is to investigate if the dynamical properties of Dark Matter and Dark Energy can be described by a single viscous fluid and how such description changes when a causal theory (Müller-IsraelStewart's, both in its full and truncated forms) is taken into account instead of Eckart's non-causal theory. To this purpose, we find numerical solutions for the gravitational potential and compare its behaviour with the corresponding ΛCDM case. Eckart's and the full causal theory seem to be disfavoured, whereas the truncated theory leads to results similar to those of the ΛCDM model for a bulk viscous speed in the interval 10 −11 ≪ c 2 b 10 −8 . Tentatively relating such value to a square propagation velocity of the order of T /m of perturbations in a non-relativistic gas of particles with mass m at the epoch of matter-radiation equality, this may be compatible with a mass range 0.1 GeV m ≪ 100 GeV.

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“…Nonetheless, this free streaming may be altered if the CMB photons encounter potential wells which evolve in time. In this case, a non-zero net energy is gained (or lost) by the photons if the potential is becoming shallower (or deeper): this phenomenon, known as the integrated Sachs-Wolfe (ISW) effect [27], leaves an imprint on the larger scales of the CMB spectrum. In the standard ΛCDM theory, this effect is expected to be generated at late times as a consequence of the potential decay when the background starts accelerating.…”

Section: Introductionmentioning

confidence: 99%

New constraints on parametrised modified gravity from correlations of the CMB with large scale structure

Giannantonio

Martinelli

Silvestri

et al. 2010

J. Cosmol. Astropart. Phys.

119

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We study the effects of modified theories of gravity on the cosmic microwave background (CMB) anisotropies power spectrum, and in particular on its large scales, where the integrated SachsWolfe (ISW) effect is important. Starting with a general parametrisation, we then specialise to f (R) theories and theories with Yukawa-type interactions between dark matter particles. In these models, the evolution of the metric potentials is altered, and the contribution to the ISW effect can differ significantly from that in the standard model of cosmology. We proceed to compare these predictions with observational data for the CMB and the ISW, performing a full Monte Carlo Markov chain (MCMC) analysis. In the case of f (R) theories, the result is an upper limit on the lengthscale associated to the extra scalar degree of freedom characterising these theories. With the addition of data from the Hubble diagram of Type Ia supernovae, we obtain an upper limit on the lengthscale of the theory of B0 < 0.4, or correspondingly λ1 < 1900 Mpc/h at 95% c.l. improving previous CMB constraints. For Yukawa-type models we get a bound on the coupling 0.75 < β1 < 1.25 at the 95% c.l. We also discuss the implications of the assumed priors on the estimation of modified gravity parameters, showing that a marginally less conservative choice improves the f (R) constraints to λ1 < 1400 Mpc/h, corresponding to B0 < 0.2 at 95% c.l.

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Perturbations of a Cosmological Model and Angular Variations of the Microwave Background

Cited by 1,729 publications

References 0 publications

Observational probes of cosmic acceleration

Observational probes of cosmic acceleration

Bulk viscous cosmology with causal transport theory

New constraints on parametrised modified gravity from correlations of the CMB with large scale structure

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