We explore the dependence of the radial alignment of subhalos on the mass of the host halo they orbit in. We have 25 well resolved host dark matter halos at our disposal ranging from 1015h-1M๏ down to 1012h-1M๏. We note that the radial alignment is independent of host halo mass and the distribution of cosθ is well fitted by a simple power law P(cosθ) ∝ cos4θ.

Using two complementary X-ray galaxy cluster studies we present new cosmological constraints on dark energy. Using Chandra measurements of the X-ray gas mass fraction, fgas, we obtain a detection of the effects of dark energy comparable in significance to recent type Ia supernovae (SNIa) studies. Using X-ray luminosity function (XLF) data from galaxy cluster surveys, we obtain the first interesting determination of the dark energy equation of state from measurements of the growth of cosmic structure in clusters. Both of our experiments provide strong, independent support to the ΛCDM paradigm.

A new cosmology based on the Bose-Einstein condensation is proposed. This is a unified model of Dark Energy and Dark Matter, and predicts several collapses of BEC, followed by the final acceleration which successfully describes the recent observational results. Furthermore, this model can be extended to the early inflationary regime, and explains natural initiation of the inflation, autonomous termination of the inflation, inevitable initiation of the reheating process, autonomous adjustment of the cosmological constant to zero, and acceptable generation of density fluctuations.

The standard model of cosmology suggests the existence of two components, “dark matter” and “dark energy”, which determine the fate of the Universe. Their nature is still under investigation, and no direct proof of their existences has emerged yet. There exist alternative models which reinterpret the cosmological observations, for example by replacing the dark energy/dark matter hypothesis by the existence of a unique dark component, the dark fluid, which is able to mimic the behaviour of both components. After a quick review of the cosmological constraints on this unifying dark fluid, we will present a model of dark fluid based on a complex scalar field and discuss the problem of the choice of the potential.

A new approach to extraction of quantum vacuum energy, in the context of the accelerated expansion, is proposed, and it is shown that experimentally realistic orders of values can be derived. The idea has been implemented in the framework of the Friedmann–Lemaître–Robertson–Walker geometry in the language of the effective action in the relativistic formalism of Schwinger's proper time and Seeley–DeWitt's heat kernel expansion.

Large amounts of invisible matter have been discovered back in 1933 when the Swiss astronomer Fritz Zwicky measured for the first time the velocity dispersion of individual galaxies inside the Coma cluster. Since then, this pioneering observation has been confirmed on scales ranging from galactic radii to cosmological distances. The existence of the so–called astronomical dark matter is now well established. The puzzle lies in the fact that this essential component of the universe is not made of ordinary atoms and electrons. The astronomical dark matter is indeed non–baryonic. Its nature is still an unresolved issue. Many theoretical ideas and proposals have flourished in the past thirty years and yet none of them provides a definite answer. I have the challenging task to introduce the cohort of these dark matter candidates to you. They make up a bestiary of exotic species which have been recently proliferating. Instead of a liste à la Prévert, I will present a tentative classification of the various models.

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.

A pseudo-Dirac neutrino of mass 50–100 GeV and mass splitting of 5 GeV can be a good candidate for dark matter. The number density of such dark matter should be close the the baryon density in order to get a dark matter density Ωm ~ 0.25. Production of heavy neutrinos by electro-weak sphaleron processes can ensure that the heavy neutrino asymmetry be of the same order as the baryon asymmetry. A mass splitting of the order.

Predictions for the direct detection rates in a variety of models with dark natter candidates are summarised. We emphasise the importance of making measurements with different spin dependent and spin independent detectors to discriminate various dark matter candidates.

Supersymmetry (SUSY) is a theoretically attractive scenario for physics beyond the Standard Model which provides a suitable Dark Matter candidate in case R-parity is conserved. If SUSY is realized at the TeV scale, as favored by several arguments, it will be accessible at the Large Hadron Collider (LHC) at CERN within the first few years of data taking. We present search strategies for generic SUSY models with R-parity conservation with the ATLAS detector at the LHC. These inclusive search strategies are 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 needed to extract the masses of SUSY particles including the undetected neutralino.

We have investigated the matter density fluctuations, δM(a), in the running ΛCDM and ΛXCDM models. The latter was proposed as an interesting solution to the cosmic coincidence problem. It includes an extra dynamical component, the “cosmon” X, which interacts with a running Λ, but not with matter. Adopting a dark energy (DE) “picture”, in which the total DE and matter components are conserved separately, the growth of density fluctuations ${\cal G}(a) = δM(a)/a can be written in terms of the effective equation of state. We made use of the measured galaxy fluctuation power spectrum, PGG, and of the linear bias parameter b2(z = 0) = PGG/PMM, where PMM ∝ δM2 is the matter power spectrum of the model under consideration. According to the 2dFGRS survey, bΛ2(z$\simeq$ 0) = 1 within a 10% accuracy for the ΛCDM model. We adopted this limit to put constraints on the fundamental parameter, ν, of the running ΛCDM model. We found an agreement with previous estimates obtained by a number of different methods and authors. This provided a good test of the procedure, which we used then to determine the physical region of the ΛXCDM parameter space.

Observations on all fronts strongly support the view of a universe composed of >96% invisible matter and energy. The invisible matter is non-baryonic, cold and likely in the form of new particles generically referred to as Weakly Interacting Massive Particles (WIMPs), relics from the early universe. One way to detect WIMPs is to measure the nuclear recoils produced in their rare elastic collisions with ordinary matter. The predicted interaction rate ranges from the best sensitivity of existing experiments of ~1 evts/kg/yr to ~1 evts/1000 kg/yr. Efforts are underway worldwide to realize sensitive direct detection experiments, with large target mass and improved background rejection capabilities. In this talk I will review experiments headed in this direction with the use of cryogenic noble liquids, focusing on those experiments which use the common technique of a dual-phase (liquid/gas) time projection chamber to measure simultaneously the ionization and the scintillation signals produced by radiation in a large volume of liquid xenon or liquid argon. These include experiments such as XENON, ZEPLIN, WARP and ArDM.

The CRESST-II direct Dark Matter search is located in the Gran Sasso underground laboratories, Italy. CaWO4 crystals are used as scintillating targets for WIMP (weakly interacting massive particle) interactions. They are operated as cryogenic calorimeters in combination with a second cryogenic detector used to measure the scintillation light produced in the target crystal. For each particle interaction, the combination of phonon and light signals provides an event by event discrimination which allows to distinguish known particles (alphas, betas, gammas, neutrons) from the expected signal of WIMPs. A major 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 accommodate up to 33 detector modules, i.e. 10 kg 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 data from one single module obtained during the CRESST-I phase, the experiment could already place a limit of ~6 × 10-7 pb for the spin independent WIMP-nucleon scattering cross section at a WIMP mass of ~60 GeV/c2.

EDELWEISS is a direct dark matter search experiment 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 types of detectors with active rejection of events due to surface contamination. This active rejection is required in order to achieve the physics goals of 10-8 pb cross-section measurement for the current phase.

Directional information should play a significant role for a firm detection of the galactic dark matter. We developed a prototype three-dimensional gaseous tracking device for a direction-sensitive dark matter direct detection. We investigated the performance of the prototype detector and demonstrated a direction-sensitive dark matter search experiment in a surface laboratory. We set the first limit on the spin-dependent WIMP (Weakly Interacting Massive Particles)-proton cross s ection by a direction-sensitive method.

EURECA (European Underground Rare Event Calorimeter Array) is an astro-particle physics facility aiming to directly detect galactic dark matter. The Laboratoire Souterrain de Modane has been selected as host laboratory. The EURECA collaboration unites CRESST, EDELWEISS and the Spanish-French experiment ROSEBUD, thus concentrating and focussing effort on cryogenic detector research in Europe into a single facility. EURECA will use a target mass of up to one ton, enough to explore WIMP – nucleon scalar scattering cross sections in the region of 10-9 – 10-10 picobarn. A major advantage of EURECA is the planned use of more than just one target material (multi target experiment for WIMP identification).

SNOLAB is a new international facility for Underground Physics that has just begun operations in Sudbury, Canada. In the following we present the current status of the facility construction and operational readiness. We also describe the experimental program and the infrastructure available to support the program, with a focus on the direct dark matter search experiments.

The MIMAC project is multi-chamber detector for Dark Matter search, aiming at measuring both track and ionization with a matrix of micromegas μTPC filled with 3He and CF4. Recent experimental results on the first measurements of the Helium quenching factor at low energy (1 keV recoil) are presented.

CRESST is an experiment for the direct detection of dark matter (WIMPs) via nuclear recoil measurement. The expected very low event rates and the low energy transfer in the keV range demand low background rates and extremely sensitive detectors. Thus the need for detector crystals with good optical and phonon properties combined with high radioactive purity arises. To achieve these goals, the control over the raw materials and their processing, in particular the crystal growth, is important. A new Czochralski furnace has been installed at the crystal laboratory of the Physik-Department in Garching to meet the delicate conditions required to grow CaWO4 crystals of sufficient size.

The current and future experimental status of indirect searches for non baryonic Dark Matter is reviewed in this article.