List of Abstracts

L. Amati, C. Guidorzi, M. della Valle, F. Frontera, F. Finelli, E. Montanari, R. Landi

Measuring cosmological parameters with the Ep,i-Eiso correlation of Gamma-Ray Bursts

Thanks to their huge luminosities (up to more than 10^53 erg/s) and their redshift distribution extending from about 0.1 to at least 6.3, Gamma-Ray Bursts (GRB)are a very powerful tool for cosmology. We have used the correlation between the photon energy at which the nuFnu spectrum peaks (Ep,i) and the total isotropic-equivalent radiated energy (Eiso)("Amati" correlation) to measure the cosmological parameter Omega_M. By exploiting the dependence of the scatter of the correlation on cosmological parameters, we constrain (for a flat universe) Omega_M to 0.02--0.40 (68% confidence level). Our approach makes no assumptions on the Ep,i-Eiso correlation and it does not use indirect calibrators to set the ``zero' point of the relation; therefore our treatment of the data is not affected by circularity and our results are independent of those derived via different cosmological probes (e.g., type Ia SNe). If we release the assumption of a flat universe, we still find evidence for a low value of Omega_M and a weak dependence of the dispersion of the Ep,i-Eiso correlation on Omega_Lambda (with an upper limit of 1.05). Simulations based on realistic extrapolations of ongoing (and future) GRB experiments (e.g., Swift, GLAST, SVOM) show that: i) the uncertainties on cosmological parameters can be significantly reduced, ii) future data will allow us to constrain the ``dark energy'' evolution.

Alexandre Arbey

Dark Energy vs. Dark Matter: Towards a unifying scalar field?

The Dark Matter and Dark Energy problems are presently two of the most important questions in cosmology. Many theoretical models try to determine the nature of these two components, however none of them has until now given a fully satisfying answer. In this talk, I will describe a scalar field model able to explain at the same time indirect observations of dark matter and of dark energy, therefore enabling to unify both components into a unique dark fluid, and I will use quantum field theory to build an adequate potential for this scalar field.

G Belanger, E. Nezri, A. Pukhov

Dark matter candidates and direct detection

The predictions for direct dark matter detection rates in various models for new physics are summarized. We discuss observables that would allow to distinguish between models, in particular the impact of improved sensitivities in the measurement of the spin-dependent WIMP-nuclei interactions is emphasized.

Boguslaw Broda, Piotr Bronowski, Marcin Ostrowski, Michal Szanecki

Quantum vacuum and accelerated expansion

It has been shown that an improved estimation of quantum vacuum energy can yield not only acceptable but also experimentally sensible results. The very idea consists in a straightforward extraction of gravitationally interacting part of the full quantum vacuum energy by means of gauge transformations. The implementation of the idea has been performed in the formalism of effective action, in the language of Schwinger's proper time and the Seeley-DeWitt heat kernel expansion, in the background of the Friedmann-Robertson-Walker geometry.

Marie-Noëlle Célérier

Challenging dark energy with exact inhomogeneous models

The dimming of the SN Ia apparent luminosity is generally ascribed to the influence of a `mysterious' dark energy component, which is supposed to yield a late- time acceleration of the Universe expansion rate. However, this interpretation assumes we are leaving in an homogeneous Universe where the influence of the inhomogeneities is negligible at all scales. Now, the last years have experienced an increase in the papers devoted to the study of such an influence and two main types of methods have been developed to deal with this problem: one is directed at evaluating backreaction effects with averaging strategies, the other makes use of models which are exact solutions of Einstein's equations and which, as they become more and more sophisticated, are able to reproduce the largest possible data sets (not only the supernovae). We will here focus our interest upon the later method and review the most achieved among the latest contributions available in the literature.

Doron Chelouche

Compact Astrophysical Objects as Direct Dark Matter Probes

We demonstrate that spectroscopic observations of compact objects - such as pulsars, magnetars, X-ray binaries, and quasars - can be used to search for photon- particle (e.g., axion) oscillation features. We show that this approach can be as much as 4(!) orders of magnitude more sensitive to oscillations than current terrestrial experiments in the mass range most relevant to dark matter searches. We discuss the implications of our results for dark matter physics.

Y. Copin (on behalf of the Nearby Supernova Factory)

The Nearby Supernova Factory: first results

The Nearby Supernova Factory (SNfactory) is an international project to discover and study a large sample of type Ia supernovae in the redshift range 0.03 < z < 0.08. Follow-up spectro-photometric observations are performed using the dedicated Supernovae Integral-Field Spectrograph (SNIFS), mounted since 2004 on 2.2 m UH telescope. The goal is to acquire for each SN and over its full life-time (more than 10 epochs) high spectro-photometric quality spectra over the extended optical range (320-1000 nm). I will present the current status of the SNfactory project, from search efficiency to first scientific results, with an emphasis on the spectro-photometric calibration issues and achievements.

C. Coppi, C. Ciemniak, F. von Feilitzsch, A. Guütlein, C. Isaila, J.-C. Lanfranchi*, S. Pfister, W. Potzel, W. Rau, S. Roth, M. Stark, W. Westphal, J. Jochum, M. Kimmerle, K. Rottler, C. Sailer, S. Scholl, I. Usherov

CRESST

The CRESST-II direct Dark Matter search is located in the Gran Sasso underground laboratories. CaWO4 crystals have been used as scintillating targets for WIMP (weakly interacting massive particle) interactions. They are operated as cryogenic calorimeters in combination with a second cryogenic detector (this combination is called a detector module) used to measure the scintillation light produced in the target crystal. For each particle interaction, the combination of phonon and light signals enables an event by event discrimination which allows distinguishing known particles (alphas, betas, gammas, neutrons) from the expected signal of WIMPs. A ma jor upgrade of the setup comprises modifications of the shielding, installation of a muon-veto, and new read out electronics, as well as a new detector-support structure to accomodate up to 33 detector modules, i.e.,10kg of target mass.The experiment was thereafter successfully commissioned in 2007. Data obtained during this commissioning phase from 2 detector modules are presented here. Combining the data collected with these two detector modules with the data from one single module obtained during the CRESST-I phase, the experiment could already place a limit of ~6 x 107 pb for the spin independent WIMP-nucleon scattering cross section at a WIMP mass of 60 GeV/c2 mass.Finally, a brief report on the status of the ongoing data taking phase with 17 detector modules installed will be given.

* Presenting author.

Till Eifert (on behalf of the ATLAS Speakers Committee)

Searches for SUSY at the LHC and its implication with Dark Matter

We present searches for generic SUSY models with R-parity conservation in the ATLAS detector at the LHC, based on signatures including missing transverse momentum from undetected neutralinos, multiple jets and leptons or b and tau jets. We show the corresponding discovery reach for the first fb-1 of ATLAS data and discuss possible measurements for extracting the masses of the involved SYSY particles including the undetected neutralino.

George Ellis

Closing Reflections

J.C.Fabris, W. Zimdahl, S.V.B. Goncalves and H. Velten

Matter power spectrum in the Generalized Chaplygin gas model

Using the 2dFGRS and SDSS data for the matter power spectrum, we constrain the free parameters of the generalized Chaplygin gas model, that is,  c, m and vs2.We use a newtonian approach.We find that a closed universe is preferred, with a very high value for $alpha$, and with a moderate value for the sound speed vs2. In general, the unification scenario, with no dark matter, is not preferred. But, the introducing of some priors change considerably this result.

Paul Hunt

Constraints on large scale voids from WMAP-5 and SDSS

Measurements of the Hubble expansion rate which suggest that the universe is accelerating due to the effect of dark energy may be biased because we are located in a large underdense `void'. The global Hubble parameter can then be ~20% smaller than its locally measured value and this allows the precision WMAP-5 data on cosmic microwave background anisotropies to be fitted without requiring dark energy, if there is also excess power in the spectrum of primordial perturbations on a scale of ~100 Mpc. The SDSS data on galaxy clustering can be fitted, in addition, if there is a 10% component of hot dark matter e.g. in the form of 0.5 eV neutrinos. We show that the variance of the Hubble parameter and the matter density in such a universe is not however large enough to do away with dark energy if the primordial fluctuations are gaussian. By the same token the void said to be responsible for the WMAP `cold spot' is extremely unlikely in a gaussian density field.

Philippe Jetzer

Limits on dark matter and cosmological constant from solar system dynamics

I will discuss the influence of the cosmological constant on the gravitational equations of motion of bodies with arbitrary masses and eventually solve the two- body problem. Observational constraints are derived from measurements of the periastron advance in stellar systems, in particular binary pulsars and the solar system. For the latter we consider also the change in the mean motion due to the cosmological constant. Up to now, Earth and Mars data give the best constraint, ~10-36 km-2. If properly accounting for the gravito-magnetic effect, this upper limit on  could greatly improve in the near future thanks to new data from planned or already operating space-missions. Dark matter or modifications of the Newtonian inverse-square law in the solar system are discussed as well. Variations in the 1/r2 behavior are considered in the form of either a possible Yukawa-like interaction or a modification of gravity of MOND type.

Julien Lavalle

Cosmological dark matter sub-halos and searches for annihilation signatures in the antimatter cosmic rays

The particle solution to the dark matter problem is very attractive because it answers some fundamental questions either in particle physics, in astrophysics and cosmology. Antimatter cosmic rays are powerful messengers to survey annihilation processes, because they are only scarcely produced in standard astrophysical phenomena. Nevertheless, some large enhancement factors are needed to make the current predictions relevant, which have been attributed to DM substructures in the past. We present some analytical studies on the enhancement that one can obtain by considering the presence of sub-halos in the Galaxy, as well as predictions directly performed on a N-body data set from the HORIZON project. We will show that no significant boost factor is expected, and underline the still interesting regions to survey in the available parameter space.

Nan Li

Signatures of cosmological backreaction

We study cosmological backreaction as a function of averaging scale in perturbation theory to higher orders. The dominant contribution comes from the averaged spatial curvature, observable up to scales of 200 Mpc. The cosmic variance of the local Hubble rate is 10% (5%) for regions of 45 (60) Mpc in linear size. We compare our result to the one from Newtonian cosmology and Hubble Space Telescope Key Project data.

A. S. Majumdar

Primordial black holes as dark matter in alternate gravity theories

We discuss the possibility of the survival of primordial black holes as dark matter candidates in various alternate gravity theories motivated from extra- dimensional scenarios. We show that in particular, braneworld black holes, as well as black holes in scalar-tensor models can survive up to late times by efficient accretion of radiation in the early universe. Possibilities of observational tests of such black holes through gravitational lensing are suggested.

F. Mayet

MIMAC : a microTPC detector for non-baryonic dar matter search

The MIMAC project aims at developing a micro-TPC matrix of He3 and CF4 chambers for direct dark matter search. The double detection (ionization and tracks) will assure the electron-recoil discrimination, and the directionnality of the tracks will open a unique way to distinguish WIMP from any background. The MIMAC project will be presented together with the first measurement of the quenching factor of He down to sub-keV energies.

Holger Motz for the ANTARES collaboration

Search for Dark Matter with the ANTARES Neutrino Telescope

ANTARES (Astronomy with a Neutrino Telescope and Abyss environmental RESearch) is the largest neutrino detector currently operating in the Northern Hemisphere. The detection principle relies on the observation of Cerenkov light emitted by muons resulting from charged current neutrino interactions in the water surrounding the detector and the seafloor below. The detector will consist of twelve lines (each carrying 75 photomultipliers) placed at a depth of about 2480 meters 40 km off the coast of Toulon, France. Ten strings are taking data since December 2007. The detector is expected to be completed in the course of 2008. ANTARES is built to search for astrophysical neutrino point sources and for neutrinos produced in self-annihilation of Dark-Matter particles. A likely source of the latter type of neutrino emission would be the Sun, where Dark Matter particles are expected to accumulate. Predictions of the high energy neutrino flux originating from the Sun have been made based on the minimal Supergravity (mSugra) model including the effect of neutrino oscillations. Within mSugra the lightest supersymmetric particle, if a neutralino, is a possible candidate for cold Dark Matter. Using the general features of ANTARES in the energy range from 10 GeV to 400 GeV the exclusion limits corresponding to three years of data taking have been calculated.

Kentaro Miuchi

Direction-sensitive Dark Matter Search --NEWAGE--

We developed a fine-pitch gaseous tracking detector for a direction-sensitive dark matter search. Our prototype detector is based on a 30×30cm2 2-dimensional imaging device and a 30cm-drift length makes the detection volume. We use a 150-torr CF4 gas as the target gas. Due to the motion of the solar system relative to the galaxy, nuclear recoils by dark matters is expected to show a very distinct direction distribution. We performed a first direction-sensitive dark matter search experiment in a surface laboratory [1]. We set a first direction-sensitive limit. We installed our detector in Kamioka underground laboratory in January 2007 and have been measuring the background there. We present the methods of our experiment and results of the 1-year underground measurement.
[1] Miuchi et.al. Phys. Lett. B654 (2007)58

Masahiro Morikawa and Takeshi Fukuyama

Early inflation and recent accelerated universe based on Bose-Einstein condensation

Cosmologists have revealed that the universe experienced the accelerated cosmic expansion twice at least; an extreme inflationary acceleration in the early universe and the recent mild acceleration. We would like to figure out the basic physics behind these accelerations and reveal the inevitability of such accelerations.
By introducing the Bose-Einstein condensation (BEC) phase of some boson field, we have already developed a unified model of dark energy (DE) and dark matter (DM). In this scenario, DE is identified with the condensation of the bosons and DM is the excited gas of the bosons. This unified model successfully explains the mild acceleration phase as the attractor. It also predicts several rapid collapses of BEC which triggers large scale structure formation and huge black holes in high redshift regime.
We extend this BEC cosmology to the early universe without introducing any new ingredients nor changing the parameter values. In our model, the inflation naturally initiates by the condensation of bosons with the huge vacuum energy of arbitrary amplitude. This inflation autonomously terminates due to the stagflation stage which inevitably takes place exactly at zero energy density. At the stagflation point, particle production and the decay of BEC take place. The former successfully connects the universe into the standard hot big bang stage and the latter guarantees the vanishingly small cosmological constant after the inflation. Further, we have calculated the density fluctuations produced in this model, which turns out to be in the range allowed by the present observational data.

Subhendra Mohanty

Fourth generation neutrino as dark matter

We investigate the possibility of a heavy fourth generation neutrino as dark matter. A lepton asymmetry in the early can give rise to a non-zero chemical potential and a closure density of heavy neutrinos. Bounds from direct searches can be evaded by (a) making them pseudo-dirac with a mass splitting of KeV order or (b) making the dark matter collapse into a compact heavy neutrino stars.

Akika Nakamichi and Masahiro Morikawa

Cosmological dark turbulence and scaling relations in self-gravitating systems

Many scaling relations have been observed for self-gravitating systems (SGS) in the universe. We explore a consistent understanding of them from a simple principle based on the proposal that the collision-less dark matter fluid terns into a turbulent state, i.e. dark turbulence, after crossing the caustic surface in the non- linear stage. After deriving Kolmogorov scaling laws from Navier-Stokes equation by the method of Smoluchowski coagulation equation, we apply this to several observations such as the scale-dependent velocity dispersion, mass-luminosity ratio, and mass- angular momentum relation. They all point the concordant value for the constant energy flow per mass: 0.3cm2 /sec3 which may be understood as the speed of the hierarchical coalescence process in the cosmic structure formation.

Jeffrey A. Newman

Calibrating Photometric Redshifts for Dark Energy Experiments with Cross-Correlation Techniques

To place constraints on the dark energy equation of state, many proposed experiments will rely critically on redshift distributions determined from photometric redshifts. The requirements are very stringent - redshift calibration uncertainties must be below 0.002(1+z) for Stage IV experiments. It is unlikely that it is possible to obtain such a robust calibration using conventional methods, as all deep spectroscopic samples are substantially (typically 10%-50% or more) incomplete, in a manner that depends on galaxy luminosity and color, even at magnitudes much shallower than future experiments will probe. In this talk, I present a new method which can meet the calibration requirements for future experiments with existing and currently-planned spectroscopic datasets; incomplete spectroscopy of the brightest objects at a given z is sufficient for this technique. Specifically, the clustering between galaxies in a photometric redshift bin and a spectroscopic sample, measured as a function of spectroscopic z, allows one to determine the true redshift distribution of objects in the bin to high accuracy, meeting or exceeding the calibration requirements of Stage IV experiments with realistic redshift samples.

Tony J. Noble

Status of SNOLAB Dark Matter Search Programme

SNOLAB is a new International Facility for underground Astroparticle Physics, currently nearing completion in Sudbury, Canada. This facility includes several new experimental halls and experimental support infrastructure. The main elements of the SNOLAB programme include a variety of experiments on low-energy solar neutrinos, dark matter, neutrinoless double beta decay, and supernovae. The status of SNOLAB as well as the status of the Dark Matter experimental programme will be discussed. The experiments approved, or being reviewed for installation at SNOLAB include DEAP/CLEAN, PICASSO, MiniClean and SuperCDMS.

Aseem Paranjape, T. P. Singh

Structure Formation, Backreaction and Weak Gravitational Fields

There is an ongoing debate in the literature as to whether the effects of averaging out inhomogeneities (``backreaction'') in Cosmology can be large enough to account for the acceleration of the scale factor in the FLRW models. In particular, some simple models of structure formation studied in the literature seem to indicate that this is indeed possible, and it has also been suggested that the perturbed FLRW framework is no longer a good approximation during structure formation, when the density contrast becomes nonlinear. In this work we attempt to clarify the situation to some extent, using a fully relativistic model of pressureless spherical collapse. We find that whereas averaging during structure formation can lead to acceleration via a selective choice of averaging domains, the acceleration is not present when more generic domains are used for averaging. Further, we show that for most of the duration of the collapse, matter velocities remain small, and the perturbed FLRW form of the metric can be explicitly recovered, in the structure formation phase. We also discuss the fact that the magnitude of the average effects of inhomogeneities depends on the scale of averaging, and while it may not be completely negligible on intermediate scales, it is expected to remain small when averaging on suitably large scales.

Piergiorgio Picozza

Dark Matter research with the PAMELA Mission

The PAMELA satellite-borne experiment was launched from the Baikonur launch site on the 15th of June 2006, and it is collecting data since July 2006. The core of the instrument is a silicon-microstrip magnetic spectrometer combined with a TOF system, a silicon-tungsten electromagnetic calorimeter, a neutron detector and a set of anticoincidence scintillators. The primary scientific goal is the measurement of the antiproton and positron energy spectra in order to search for exotic sources, such as dark matter particle annihilations. Preliminary results concerning antiparticle measurements and dark-matter indirect searches will be presented.

Matt Pyle and the CDMS collaboration

Challenges faced in CDMS II and their consequences in the future

We will present the most recent and current world leading limits for spin independent wimp interaction with baryonic matter from the Cryogenic Dark Matter Search (CDMS II) with particular emphasis on the difficulties/challenges faced during design, fabrication, deployment and analysis of the current experiment. We'll then look to the future, and discuss ways to mitigate these problems in the next larger generation.

S. Rasanen

The effect of structure formation on the expansion of the Universe

When structure formation is taken into account, it is possible for the expansion of the universe to accelerate without dark energy or modified gravity. I will discuss recent work on calculating the expansion rate in a statistically homogeneous and isotropic universe with evolving non-linear structures. One of the main results is that a preferred time of 10-100 billion years for the change in the expansion rate emerges without any free parameters.

Anais Rassat for the Euclid collaboration

Combined Analysis of Dark Energy with Euclid

The Dark UNiverse Explorer (DUNE) is a wide-field space imager whose primary goal is the study of dark energy and dark matter with unprecedented precision. The mission is optimised for weak gravitational lensing, and also uses Baryon Accoustic Oscillations, cluster counts and the Integrated Sachs Wolfe effect as complementary cosmological probes. Immediate secondary goals concern the evolution of galaxies, the detailed structure of the Milky Way and nearby galaxies, and the demographics of Earth-mass planet. DUNE is an Medium-class mission with limited risks and costs consisting of a 1.2m telescope with a combined visible/NIR field-of-view of 1 sq. deg. DUNE will carry out an all-sky survey in one visible and three NIR bands which will form a unique legacy for astronomy and will make full use of synergies with ground based facilities. DUNE is a realisation of the wide-field imaging mission recommended by the ESO/ESA Working Group on Fundamental Cosmology. DUNE has recently been selected by ESA as one of the concept to be studied for an Assessment Phase within its Cosmic Vision programme. DUNE addresses multiple goals of this programme, including fundamental cosmology, galaxy evolution, and extrasolar planet search, and will yield major advances in a broad range of fields in astrophysics and cosmology.

Véronique Sanglard

Status of EDELWEISS-II

EDELWEISS is a direct dark matter search situated in the low radioactivity environment of the Modane Underground Laboratory. The experiment uses Ge detectors at very low temperature in order to identify eventual rare nuclear recoils induced by elastic scattering of WIMPs from our Galactic halo. We present results of the commissioning of the second phase of the experiment, involving more than 7 kg of Ge, that has been completed in 2007. We describe two new type of detectors with active rejection of events due to surface contamination, which is a requirement for achieving the physics goals of the present phase.

Frank Steiner

CMB and the Present Status of Cosmic Topology

The present status of cosmic topology is reviewed. The analysis is based on extensive simulations of CMB sky maps for Friedmann-Lemai^tre universes with flat, positive or negative spatial curvature, and a detailed comparison with the WMAP data.

Paolo Salucci

The Universal Rotation Curve of Spiral Galaxies.

In the current LambdaCDM cosmological scenario, N-body simulations provide us with a Universal mass profile, and consequently a Universal equilibrium circular velocity of the virialized objects, e.g. galaxies. I will show how, by combining kinematical data of their inner regions with global observational properties, we can derive the Universal Rotation Curve (URC) of disk galaxies and the corresponding distribution of the dark and luminous mass, out to their virial radii. I will finally discuss the various agreements and disagreements between the observational and CDM theorethical scenarios of the mass distribution in galaxies.

Szydlowski, A. Kurek, A. Krawiec

The sensitivity of dark energy parameters on a prior choice

We examine the dependence of the Bayesian evidence on a prior choice for the FRW model with different forms of dark energy. We also study differences between the Bayesian evidence and BIC with respect to accuracy of parameters. We point out that the advantage of the Bayesian evidence is sensitive to accuracy of parameter estimation. We illustrate the sensitivity of estimation of quintessence models (the equation of state parameter w(z)) with respect to the choice of prior on initial condition for the scalar field and its derivative.

Mathieu Vivier

HESS

The H.E.S.S instrument is an array of four imaging atmospheric Cherenkov telescopes (IACT) dedicated to the detection of very high energy gamma-rays in the TeV regime. Since the annihilation of WIMPs can lead to high energy gamma-rays in the final state, H.E.S.S. is an interesting instrument for the indirect detection of Dark Matter (DM). Potential targets are large DM density astrophysical objects such as galactic centers. Constraints on the WIMP velocity-weighted annihilation cross-section given by the observations of three targets: the Galactic Center, the Sagittarius and the Canis Major dwarf spheroidal galaxies will be discussed. Constraints on the velocity-weighted annihilation cross-section in the framework of DM mini-spikes scenarios around Intermediate Mass Black Hole (IMBHs) will be also briefly presented.

David L. Wiltshire

Gravitational energy as dark energy: Towards concordance cosmology without Lambda

A decade of observations suggest that the universe is currently undergoing accelerated expansion, driven by a mysterious vacuum energy. I will present an alternative, unexpected, explanation for dark energy, purely within general relativity [1]. Cosmic acceleration is explained quantitatively, as an apparent effect due to quasilocal gravitational energy differences that arise in the decoupling of bound systems from the global expansion of the universe. Although the universe was initially very smooth, today it is very inhomogeneous on scales less than 200 Mpc, with clusters of galaxies strung in filaments and bubbles surrounding huge voids. Accounting for spatial curvature and gravitational energy gradients between galaxies and the volume average location in voids from first principles, leads to a recalibration of average cosmological parameters, and a rewriting of the standard model of cosmology. I present an observationally viable model [1,2] of the universe based on this proposal, which passes three key independent cosmological tests [3]: supernova luminosity distances, the angular scale of the sound horizon in the cosmic microwave background (CMB) and the baryon acoustic oscillation scale in galaxy clustering statistics - and simultaneously resolves particular anomalies, including primordial lithium abundances and CMB ellipticity. The expansion age is increased allowing more time for structure formation. Best-fit parameters are cosmological parameters are presented, including an age of the universe of 14.7 billion years measured in galaxies, a ratio of non-baryonic dark matter to baryonic matter of 3:1, and a void volume fraction of 76%. Other unique predictions are made, including a quantifiable variance in the Hubble flow below the scale of apparent homogeneity, consistent with the observed „Hubble bubble“ feature, and with the potential to offer new observational tests.
References
[1] D.L. Wiltshire, New J. Phys. 9 (2007) 377, Cosmic clocks, cosmic variance and cosmic averages
[2] D.L. Wiltshire, Phys. Rev. Lett. 99 (2007) 251101, Exact solution to the averaging problem in cosmology
[3] B.M. Leith, S.C.C. Ng and D.L. Wiltshire, Astrophys. J. 672 (2008) L91, Gravitational energy as dark energy: Concordance of cosmological tests
[4] D.L. Wiltshire, arxiv:0712.3984, Dark energy without dark energy