Kaluza-Klein Dark Matter, Electrons and Gamma Ray Telescopes

Kaluza-Klein dark matter particles can annihilate efficiently into electron-positron pairs, providing a discrete feature (a sharp edge) in the cosmic $e^+ e^-$ spectrum at an energy equal to the particle's mass (typically several hundred GeV to one TeV). Although this feature is probably beyond the reach of satellite or balloon-based cosmic ray experiments (those that distinguish the charge and mass of the primary particle), gamma ray telescopes may provide an alternative detection method. Designed to observe very high-energy gamma-rays, ACTs also observe the diffuse flux of electron-induced electromagnetic showers. The GLAST satellite, designed for gamma ray astronomy, will also observe any high energy showers (several hundred GeV and above) in its calorimeter. We show that high-significance detections of an electron-positron feature from Kaluza-Klein dark matter annihilations are possible with GLAST, and also with ACTs such as HESS, VERITAS or MAGIC.Comment: 10 pages, 2 figure

Two photon annihilation of Kaluza-Klein dark matter

We investigate the fermionic one-loop cross section for the two photon annihilation of Kaluza-Klein (KK) dark matter particles in a model of universal extra dimensions (UED). This process gives a nearly mono-energetic gamma-ray line with energy equal to the KK dark matter particle mass. We find that the cross section is large enough that if a continuum signature is detected, the energy distribution of gamma-rays should end at the particle mass with a peak that is visible for an energy resolution of the detector at the percent level. This would give an unmistakable signature of a dark matter origin of the gamma-rays, and a unique determination of the dark matter particle mass, which in the case studied should be around 800 GeV. Unlike the situation for supersymmetric models where the two-gamma peak may or may not be visible depending on parameters, this feature seems to be quite robust in UED models, and should be similar in other models where annihilation into fermions is not helicity suppressed. The observability of the signal still depends on largely unknown astrophysical parameters related to the structure of the dark matter halo. If the dark matter near the galactic center is adiabatically contracted by the central star cluster, or if the dark matter halo has substructure surviving tidal effects, prospects for detection look promising.Comment: 17 pages, 3 figures; slightly revised versio

The Role of Antimatter Searches in the Hunt for Supersymmetric Dark Matter

We analyze the antimatter yield of supersymmetric (SUSY) models with large neutralino annihilation cross sections. We introduce three benchmark scenarios, respectively featuring bino, wino and higgsino-like lightest neutralinos, and we study in detail the resulting antimatter spectral features. We carry out a systematic and transparent comparison between current and future prospects for direct detection, neutrino telescopes and antimatter searches. We demonstrate that often, in the models we consider, antimatter searches are the only detection channel which already constrains the SUSY parameter space. Particularly large antiprotons fluxes are expected for wino-like lightest neutralinos, while significant antideuteron fluxes result from resonantly annihilating binos. We introduce a simple and general recipe which allows to assess the visibility of a given SUSY model at future antimatter search facilities. We provide evidence that upcoming space-based experiments, like PAMELA or AMS, are going to be, in many cases, the unique open road towards dark matter discovery.Comment: 34 pages, 18 figures; V2: misprints in the labels of fig. 2,3 and 5 correcte

Determining the WIMP mass using the complementarity between direct and indirect searches and the ILC

We study the possibility of identifying dark matter properties from XENON-like 100 kg experiments and the GLAST satellite mission. We show that whereas direct detection experiments will probe efficiently light WIMPs, given a positive detection (at the 10% level for $m_{\chi} \lesssim 50$ GeV), GLAST will be able to confirm and even increase the precision in the case of a NFW profile, for a WIMP-nucleon cross-section $\sigma_{\chi-p} \lesssim 10^{-8}$ pb. We also predict the rate of production of a WIMP in the next generation of colliders (ILC), and compare their sensitivity to the WIMP mass with the XENON and GLAST projects.Comment: 32 pages, new figures and a more detailed statistical analysis. Final version to appear in JCA

Direct versus indirect detection in mSUGRA with self-consistent halo models

We perform a detailed analysis of the detection prospects of neutralino dark matter in the mSUGRA framework. We focus on models with a thermal relic density, estimated with high accuracy using the DarkSUSY package, in the range favored by current precision cosmological measurements. Direct and indirect detection rates are computed implementing two models for the dark matter halo, tracing opposite regimes for the phase of baryon infall, with fully consistent density profiles and velocity distribution functions. This has allowed, for the first time, a fully consistent comparison between direct and indirect detection prospects. We discuss all relevant regimes in the mSUGRA parameter space, underlining relevant effects, and providing the basis for extending the discussion to alternative frameworks. In general, we find that direct detection and searches for antideuterons in the cosmic rays seems to be the most promising ways to search for neutralinos in these scenarios.Comment: 26 pages, 9 figure

Results from PAMELA, ATIC and FERMI : Pulsars or Dark Matter ?

It is well known that the dark matter dominates the dynamics of galaxies and clusters of galaxies. Its constituents remain a mystery despite an assiduous search for them over the past three decades. Recent results from the satellite-based PAMELA experiment detect an excess in the positron fraction at energies between 10-100 GeV in the secondary cosmic ray spectrum. Other experiments namely ATIC, HESS and FERMI show an excess in the total electron (\ps + \el) spectrum for energies greater 100 GeV. These excesses in the positron fraction as well as the electron spectrum could arise in local astrophysical processes like pulsars, or can be attributed to the annihilation of the dark matter particles. The second possibility gives clues to the possible candidates for the dark matter in galaxies and other astrophysical systems. In this article, we give a report of these exciting developments.Comment: 27 Pages, extensively revised and significantly extended, to appear in Pramana as topical revie

Determining Supersymmetric Parameters With Dark Matter Experiments

In this article, we explore the ability of direct and indirect dark matter experiments to not only detect neutralino dark matter, but to constrain and measure the parameters of supersymmetry. In particular, we explore the relationship between the phenomenological quantities relevant to dark matter experiments, such as the neutralino annihilation and elastic scattering cross sections, and the underlying characteristics of the supersymmetric model, such as the values of mu (and the composition of the lightest neutralino), m_A and tan beta. We explore a broad range of supersymmetric models and then focus on a smaller set of benchmark models. We find that by combining astrophysical observations with collider measurements, mu can often be constrained far more tightly than it can be from LHC data alone. In models in the A-funnel region of parameter space, we find that dark matter experiments can potentially determine m_A to roughly +/-100 GeV, even when heavy neutral MSSM Higgs bosons (A, H_1) cannot be observed at the LHC. The information provided by astrophysical experiments is often highly complementary to the information most easily ascertained at colliders.Comment: 46 pages, 76 figure

Probing Neutralino Resonance Annihilation via Indirect Detection of Dark Matter

The lightest neutralino of R-parity conserving supersymmetric models serves as a compelling candidate to account for the presence of cold dark matter in the universe. In the minimal supergravity (mSUGRA) model, a relic density can be found in accord with recent WMAP data for large values of the parameter $\tan\beta$, where neutralino annihilation in the early universe occurs via the broad s-channel resonance of the pseudoscalar Higgs boson $A$. We map out rates for indirect detection of neutralinos via 1. detection of neutrinos arising from neutralino annihilation in the core of the earth or sun and 2. detection of gamma rays, antiprotons and positrons arising from neutralino annihilation in the galactic halo. If indeed $A$-resonance annihilation is the main sink for neutralinos in the early universe, then signals may occur in the gamma ray, antiproton and positron channels, while a signal in the neutrino channel would likely be absent. This is in contrast to the hyperbolic branch/focus point (HB/FP) region where {\it all} indirect detection signals are likely to occur, and also in contrast to the stau co-annihilation region, where {\it none} of the indirect signals are likely to occur.Comment: 12 pages including 4 eps figure

Adiabatic compression and indirect detection of supersymmetric dark matter

Recent developments in the modelling of the dark matter distribution in our Galaxy point out the necessity to consider some physical processes to satisfy observational data. In particular, models with adiabatic compression, which include the effect of the baryonic gas in the halo, increase significantly the dark matter density in the central region of the Milky Way. On the other hand, the non-universality in scalar and gaugino sectors of supergravity models can also increase significantly the neutralino annihilation cross section. We show that the combination of both effects gives rise to a gamma-ray flux arising from the Galactic Center largely reachable by future experiments like GLAST. We also analyse in this framework the EGRET excess data above 1 GeV, as well as the recent data from CANGAROO and HESS. The analysis has been carried out imposing the most recent experimental constraints, such as the lower bound on the Higgs mass, the \bsg branching ratio, and the muon $g-2$. In addition, the recently improved upper bound on $B(B_s \to \mu^+ \mu^-)$ has also been taken into account. The astrophysical (WMAP) bounds on the dark matter density have also been imposed on the theoretical computation of the relic neutralino density through thermal production.Comment: 32 pages, 11 figures, final version to appear in JCA

Fitting the Gamma-Ray Spectrum from Dark Matter with DMFIT: GLAST and the Galactic Center Region

We study the potential of GLAST to unveil particle dark matter properties with gamma-ray observations of the Galactic center region. We present full GLAST simulations including all gamma-ray sources known to date in a region of 4 degrees around the Galactic center, in addition to the diffuse gamma-ray background and to the dark matter signal. We introduce DMFIT, a tool that allows one to fit gamma-ray emission from pair-annihilation of generic particle dark matter models and to extract information on the mass, normalization and annihilation branching ratios into Standard Model final states. We assess the impact and systematic effects of background modeling and theoretical priors on the reconstruction of dark matter particle properties. Our detailed simulations demonstrate that for some well motivated supersymmetric dark matter setups with one year of GLAST data it will be possible not only to significantly detect a dark matter signal over background, but also to estimate the dark matter mass and its dominant pair-annihilation mode.Comment: 37 pages, 16 figures, submitted to JCA