Signature of the interaction between dark energy and dark matter in galaxy clusters

We investigate the influence of an interaction between dark energy and dark matter upon the dynamics of galaxy clusters. We obtain the general Layser–Irvine equation in the presence of interactions, and find how, in that case, the virial theorem stands corrected. Using optical, X-ray and weak lensing data from 33 relaxed galaxy clusters, we put constraints on the strength of the coupling between the dark sectors. Available data suggests that this coupling is small but positive, indicating that dark energy might be decaying into dark matter. Systematic effects between the several mass estimates, however, should be better known, before definitive conclusions on the magnitude and significance of this coupling could be established.     

Constraints on the interaction between dark matter and Baryons from cooling flow clusters

Other nongravitational heating processes are needed to resolve the disagreement between the absence of cool gas components in the centers of galaxy clusters revealed recently by Chandra and XMM observations and the expectations of conventional radiative cooling models. We propose that the interaction between dark matter and baryonic matter may act as an alternative for the reheating of intracluster medium (ICM) in the inner regions of clusters, in which kinetic energy of dark matter is transported to ICM to balance radiative cooling. Using the Chandra and XMM data, we set a useful constraint on the dark-matter-baryon cross section: sigma(xp)/m(x) approximately 1x10(-25) cm(2) GeV-1, where m(x) is the mass of dark matter particles.     

Light neutralino dark matter in the pMSSM

We present an investigation of the dependence of searches for boosted Higgs bosons using jet substructure on the perturbative and non-perturbative parameters of the Herwig++ Monte Carlo event generator. Values are presented for a new tune of the parameters of the event generator, together with the an estimate of the uncertainties based on varying the parameters around the best-fit values.     

Gamma rays from heavy neutralino dark matter

We consider the gamma-ray spectrum from neutralino dark matter annihilations and show that internal bremsstrahlung of pair final states gives a previously neglected source of photons at energies near the mass of the neutralino. For masses larger than about 1 TeV, and for present day detector resolutions, this results in a characteristic signal that may dominate not only over the continuous spectrum from W fragmentation, but also over the gammagamma and gammaZ line signals which are known to give large rates for heavy neutralinos. Observational prospects thus seem promising.     

Explosive dark matter annihilation

In this Letter we study pair annihilation processes of dark matter (DM) in the Universe, in the case that the DM is an electroweak gauge nonsinglet. In the current Universe, in which the DM is highly nonrelativistic, the nonperturbative effect may enhance the DM annihilation cross sections, especially for that to two photons, by several orders of magnitude. We also discuss sensitivities in future searches for anomalous gamma rays from the galactic center, which originate from DM annihilation.     

Neutrino indirect detection of neutralino dark matter in the CMSSM

We study potential signals of neutralino dark matter indirect detection by neutrino telescopes in a wide range of CMSSM parameters. We also compare with direct detection potential signals taking into account in both cases present and future experiment sensitivities. Only models with neutralino annihilation into gauge bosons can satisfy cosmological constraints and current neutrino indirect detection sensitivities. For both direct and indirect detection, only next generation experiments will be able to really test this kind of models. Received: 12 April 2002 / Revised version: 16 July 2002 / Published online: 18 October 2002 RID="a" ID="a" e-mail: bertin@cppm.in2p3.fr RID="b" ID="b" e-mail: nezri@in2p3.fr RID="c" ID="c" e-mail: orloff@in2p3.fr     

Nonabelian dark matter with resonant annihilation

Journal of High Energy Physics - This paper shows that the positive-energy and non-renormalization theorems of traditional supersymmetry survive the addition of Lorentz violating interactions. The...     

On the interaction of high-energy cosmic leptons with neutralino dark matter

The interaction of neutralino cold dark matter with cosmic-ray electrons is considered in terms of the supersymmetric Standard Model. The production of heavy supersymmetric particles in collisions and their decay are shown to give rise to leptons and neutrinos with certain energies and to relativistic neutralinos. The possibility of detecting dark matter through its interaction with cosmic rays is discussed.     

Implications of the pseudo-scalar Higgs boson in determining the neutralino dark matter

In the framework of the constrained minimal supersymmetric standard model (CMSSM) we discuss the impact of the pseudo-scalar Higgs boson in delineating regions of the parameters which are consistent with cosmological data and E821 data on the anomalous magnetic moment of the muon. For the large values of the parameter , cosmologically allowed corridors of large are opened, due to the s-channel pseudo-scalar exchange in the pair annihilation of the lightest of the neutralinos to or , which dominates in this region. However, no such corridors are found for values . Combining cosmological and E821 data puts severe upper limits on the sparticle masses. We find that at LHC, but even at a linear collider with center of mass energy GeV, such as TESLA, supersymmetry can be discovered, if it is based on the CMSSM. Received: 22 July 2001 / Revised version: 13 November 2001 / Published online: 18 January 2002     

Monochromatic neutrino signals from dark matter annihilation

Dark matter (DM) annihilations in the Sun to neutrino–antineutrino pairs are known to have potentially observable signatures in neutrino telescopes such as IceCube and KM3. We propose a model independent analysis in which the monochomatic neutrino signal from dark matter (DM) annihilations in the Sun is related to the direct detection spin-independent and spin-dependent cross sections rather than assuming cross sections from a particular model. We propagate the neutrinos from the center of the Sun to the Earth taking into account matter effects on neutrino oscillations. For DM capture in the Sun via a large spin-dependent DM capture cross section the discovery prospects of the IceCube experiment are found to be promising.     

Constraints on dark matter annihilation from M87

As the largest mass concentrations in the local Universe, nearby clusters of galaxies and their central galaxies are prime targets in searching for indirect signatures of dark matter annihilation (DMA). We seek to constrain the dark matter annihilation emission component from multi-frequency observations of the central galaxy of the Virgo cluster. The annihilation emission component is modeled by the prompt and inverse-Compton gamma rays from the hadronization of annihilation products from generic weakly interacting dark matter particles. This component is fitted to the excess of the observed data above the spectral energy distribution (SED) of the jet in M87, described with a best-fit synchrotron-self-Compton (SSC) spectrum. While this result is not sufficiently significant to claim a detection, we emphasize that a dark matter “double hump signature” can be used to unambiguously discriminate the dark matter emission component from the variable jet-related emission of M87 in future, more extended observation campaigns.     

Spin in the dark matter problem

Weakly interacting massive particles (WIMPs) are among the main candidates for the relic dark matter (DM). The idea of direct DM detection relies on elastic spin-dependent (SD) and spin-independent (SI) interaction of WIMPs with target nuclei. In this review, formulas for the DM event rate calculations are collected. The importance of the SD WIMP-nucleus interaction for reliable DM detection is argued and the spin nuclear structure functions relevant to DM search are discussed. The effective low-energy minimal supersymmetric standard model (MSSM) is used for calculation of the DM cross sections, provided the lightest neutralino is the WIMP. It is shown that the absolute lower bound for the rate of direct DM detection is due to the SD WIMP-nucleon interaction and a new-generation experiment aimed at detecting DM with sensitivity higher than 10⁻⁵ event/day/kg should have a non-zero-spin target to avoid missing of the DM signal. The mixed spin-scalar couplings approach is argued. Prospects of DM experiments with high-spin Ge-73 are discussed in the mixed coupling scheme. The DAMA experiment has claimed observation of WIMPs due to annual signal modulation. Some important consequences of the DAMA claim for the other DM searches as well as for collider physics are considered. The text was submitted by the author in English.