Using gamma-ray data from observations of the Milky Way, Andromeda (M31), and the cosmic background, we calculate conservative upper limits on the dark matter self-annihilation cross section to monoenergetic gamma rays, <sigma_A v>_{gamma gamma}, over a wide range of dark matter masses. (In fact, over most of this range, our results are unchanged if one considers just the branching ratio to gamma rays with energies within a factor of a few of the endpoint at the dark matter mass.) If the final-state branching ratio to gamma rays, Br(gamma gamma), were known, then <sigma_A v>_{gamma gamma} / Br(gamma gamma) would define an upper limit on the total cross section; we conservatively assume Br(gamma gamma) > 10^{-4}. An upper limit on the total cross section can also be derived by considering the appearance rates of any Standard Model particles; in practice, this limit is defined by neutrinos, which are the least detectable. For intermediate dark matter masses, gamma-ray-based and neutrino-based upper limits on the total cross section are comparable, while the gamma-ray limit is stronger for small masses and the neutrino limit is stronger for large masses. We comment on how these results depend on the assumptions about astrophysical inputs and annihilation final states, and how GLAST and other gamma-ray experiments can improve upon them.
Annihilation of clumped superheavy dark matter provides an interesting explanation for the origin of ultrahigh energy cosmic rays. The predicted anisotropy signal provides a unique signature for this scenario.
We discuss the detectability of dark matter clumps in the Milky Way halo due to neutralino annihilation. We then focus on a known ``clump'', the Large Magellanic Cloud.
We re-examine collisional annihilation of superheavy dark matter particles in dark matter density spikes in the galactic halo as a possible source of ultrahigh energy cosmic rays. We estimate the possible flux in a way that does not depend on detailed assumptions about the density profiles of dark matter clumps. The result confirms that collisional annihilation is compatible with annihilation cross sections below the unitarity bounds for superheavy dark matter if the particles can form dense cores in dark matter substructure, and it provides estimates for core sizes and densities. The ensuing …
The neutralino, the lightest stable supersymmetric particle, is a strong theoretical candidate for the missing astronomical ``dark matter''. A profusion of such neutralinos can accumulate near the Sun when they lose energy upon scattering and are gravitationally captured. Pair-annihilations of those neutralinos may produce very high energy (VHE, above $100 GeV$) gamma-rays. Milagro is an air shower array which uses the water Cherenkov technique to detect extensive air showers and is capable of observing VHE gamma-rays from the direction of the Sun with an angular resolution of $0.75^{\circ}$. …
We investigate the possibility that ultra-high energy cosmic rays (UHECRs) originate from the annihilation of relic superheavy (SH) dark matter in the Galactic halo. In order to fit the data on UHECRs, a cross section of $<σ_Av>\sim 10^{-26}\textrm{cm}^2 (M_X/10^{12} \textrm{GeV})^{3/2}$ is required if the SH dark matter follows a Navarro--Frenk--White (NFW) density profile. This would require extremely large-$l$ contributions to the annihilation cross section. An interesting finding of our calculation is that the annihilation in sub-galactic clumps of dark matter dominates over the annihilati…
The majority of mass in the universe has not been observed optically and is termed dark matter. The supersymmetric neutralino provides an interesting dark matter candidate, which may self-annihilate in our galaxy, producing particles visible in the cosmic ray spectrum. During a ten day space shuttle flight, the AMS-01 detector recorded over 100 million cosmic ray events. This analysis searches for the products of neutralino annihilation in the AMS-01 Z=-1 spectrum, and uses the results to place limits on which supersymmetric and dark matter halo distribution models are compatible.
Intermediate Mass Black Holes (IMBHs) are candidates to seed the Supermassive Black Holes (SMBHs), and some could still wander in the Galaxy. In the context of annihilating dark matter (DM), they are expected to drive huge annihilation rates, and could therefore significantly enhance the primary cosmic rays (CRs) expected from annihilation of the DM of the Galactic halo. In this proceeding (the original paper is Brun et al. 2007), we briefly explain the method to derive estimates of such exotic contributions to the anti-proton and positron CR spectra, and the associated statistical uncertainti…
Cosmic rays with energies exceeding $10^{20}\eV$ have been detected. The origin of these highest energy cosmic rays remains unknown. Established astrophysical acceleration mechanisms encounter severe difficulties in accelerating particles to these energies. Alternative scenarios where these particles are created by the decay of cosmic topological defects have been suggested in literature. In this paper we study the possibility of producing the highest energy cosmic rays through a process that involves formation of metastable magnetic monopole-antimonopole bound states and their subsequent coll…
The extragalactic background (EGB) of diffuse gamma rays can be determined by subtracting the Galactic contribution from the data. This requires a Galactic model (GM) and we include for the first time the contribution of dark matter annihilation (DMA), which was previously proposed as an explanation for the EGRET excess of diffuse Galactic gamma rays above 1 GeV. In this paper it is shown that the newly determined EGB shows a characteristic high energy bump on top of a steeply falling soft contribution. The bump is shown to be compatible with a contribution from an extragalactic DMA signal fro…
We estimate the probability of detecting gamma-rays from the annihilation of neutralino dark matter in the substructure of the Milky Way. We characterize substructure statistically based on Monte Carlo realizations of the formation of a Milky Way-like halo using semi-analytic methods that have been calibrated against N-body simulations. We find that it may be possible for the upcoming GLAST and VERITAS experiments, working in concert, to detect gamma-rays from dark matter substructure if $\Mchi \lsim 100 \GeV$, while for $\Mchi \gsim 500 \GeV$ such a detection seems unlikely. We investigate th…
The H.E.S.S. array of Cherenkov telescopes has performed, from 2004 to 2007, a survey of the inner Galactic plane at photon energies above 100 GeV. About 400 hours of data have been accumulated in the region between -30 and +60 degrees in Galactic longitude, and between -3 and +3 degrees in Galactic latitude. Assuming that dark matter is composed of Weakly Interacting Massive Particles, we calculate here the H.E.S.S. sensitivity map for dark matter annihilations, and derive the first experimental constraints on the ''mini-spikes'' scenario, in which a gamma-ray signal arises from dark matter a…
Recent studies have suggested the possibility that the lightest supersymmetric particle is a suitable dark matter candidate. In this theoretical framework, annihilations in high density environments like the center of dark matter haloes may produce an intense flux of gamma-rays. In this paper we discuss the possibility of detecting the signatures of neutralino annihilation in nearby galaxies with next generation ground-based detectors.
The EGRET excess of diffuse Galactic gamma rays shows all the features expected from dark matter annihilation (DMA): a spectral shape given by the fragmentation of mono-energetic quarks, which is the same in all sky directions and an intensity distribution of the excess expected from a standard dark matter halo, predicted by the rotation curve. From the EGRET excess one can predict the flux of antiprotons from DMA. However, how many antiprotons arrive at the detector strongly depends on the propagation model. The conventional isotropic propagation models trap the antiprotons in the Galaxy lead…
We calculate the flux of cosmic gamma rays expected {}from the annihilation of neutralinos in the Galactic halo. Our calculation of the annihilation cross section to two photons improves the existing calculations by inclusion of exact one-loop diagrams for the amplitudes involving Higgs boson and chargino states as well as those involving fermion and sfermion states. A survey of supersymmetric parameter space shows that numerous models would be observable at the $3σ$ level with an air Cerenkov telescope with an exposure of $10^4 \meter^2 \yr$.
Elsaesser and Mannheim fit a contribution of Dark Matter Annihilation (DMA) to the extragalactic contribution of the galactic diffuse gamma ray flux, as deduced from the EGRET data by Strong, Moskalenko and Reimer.They find a WIMP mass of 515{+110}{-75} GeV and quote a systematic error of 30\%. However, they do not include large systematic uncertainties from the fact that the determination of the extragalactic flux (EGF) requires a model for the subtraction of the Galactic flux from the data.The data used were obtained with a model without Galactic DM, so one expects additional uncertainty in …
Annihilating dark matter particles produce roughly as much power in electrons and positrons as in gamma ray photons. The charged particles lose essentially all of their energy to inverse Compton and synchrotron processes in the galactic environment. We discuss the diffuse signature of dark matter annihilations in satellites of the Milky Way (which may be optically dark with few or no stars), providing a tail of emission trailing the satellite in its orbit. Inverse Compton processes provide X-rays and gamma rays, and synchrotron emission at radio wavelengths might be seen. We discuss the possib…
We study the indirect detection of neutralino dark matter using positrons and gamma rays from its annihilation in the galactic halo. Considering the HESS data as the spectrum constituting the gamma--ray background, we compare the prospects for the experiments GLAST and PAMELA in a general supergravity framework with non--universal scalar and gaugino masses. We show that with a boost factor of about 10, PAMELA will be competitive with GLAST for typical NFW cuspy profiles.
I discuss contributions to the diffuse gamma-ray background from decay and annihilation of weakly interacting massive particles (WIMPs). I first review the calculation of the cosmological abundance of a WIMP and show that it is simply related to the cross section for annihilation of the WIMP into lighter particles. The diffuse extragalactic background radiation (DEBRA) from WIMP decay is then discussed. I show how observational upper limits to the DEBRA can be used to constrain properties of WIMPs that decay to photons, and I present additional new constraints that unitarity of the annihilatio…
Some part of the relic Dark Matter is distributed in small-scale clumps which survived structure formation in inflation cosmological scenario. The annihilation of DM inside these clumps is a strong source of stable charged particles which can have a substantial density near the clump core. The streaming of the annihilation products from the clump can enhance irregularities in the galactic magnetic field. This can produce small scale variations in diffusion coefficient affecting propagation of Cosmic Rays.
We investigate a scenario where the recently discovered non-thermal hard X-ray emission from the Ophiuchus cluster originates from inverse Compton scattering of energetic electrons and positrons produced in weakly interacting dark matter pair annihilations. We show that this scenario can account for both the X-ray and the radio emission, provided the average magnetic field is of the order of 0.1 microGauss. We demonstrate that GLAST will conclusively test the dark matter annihilation hypothesis. Depending on the particle dark matter model, GLAST might even detect the monochromatic line produce…
High resolution simulations reveal that in the cold dark matter scenario the structures form hierarchically and a large number of substructures survive in the galactic halos. The substructures can be probed if they emit gamma rays via dark matter annihilation. We calculated the gamma ray fluxes from the dark matter annihilations in the substructures of our Galaxy within the frame of the minimal supersymmetric extension of the standard model. The uncertainties of the prediction from both the low energy supersymmetry and especially from the density profiles of dark matter in the substructures ar…
We consider neutralino annihilation in dense extragalactic systems known to be dominated by dark matter, in particular M87 and several local dwarf spheroidal galaxies. These annihilations can produce energetic gamma rays which may be visible to atmospheric Cerenkov telescopes. We explore the supersymmetric parameter space, and compute the expected flux of gamma--rays coming from these objects. It is shown that some parts of the parameter space lead to a signal observable with the next generation of Cerenkov telescopes, provided the supersymmetric dark matter has a clumpy structure, as may be e…
Annihilation of high energy, $\sim 10^{21}$eV, neutrinos on big bang relic neutrinos of $\sim 1$eV mass, clustered in the Galactic halo or in a nearby galaxy cluster halo, has been suggested to generate, through hadronic Z decay, high energy nucleons and photons which may account for the detected flux of >10^{20}eV cosmic-rays. We show that the flux of high energy nucleons and photons produced by this process is dominated by annihilation on the uniform, non-clustered, neutrino background, and that the energy generation rate of 10^{21}eV neutrinos required to account for the detected flux of >1…
We estimate the probability of detecting gamma-rays from the annihilation of neutralino dark matter in dense, central regions of Milky Way substructure. We characterize Galactic substructure statistically based on Monte Carlo realizations of the formation of a Milky Way-like halo using a semi-analytic method that has been calibrated against the results of high-resolution N-body simulations. We find that it may be possible for the upcoming experiments GLAST and VERITAS, working in concert, to detect gamma-rays from dark matter substructure if the neutralino is relatively light ($\Mchi \lsim 100…
Atmospheric Cerenkov Telescopes, including HESS and MAGIC, have detected a spectrum of gamma-rays from the galactic center region which extends from $\sim$200 GeV or lower, to at least $\sim$10 TeV. Although the source of this radiation is not yet known, the spectrum appears to behave as a simple power-law, which is not the expectation for gamma-rays generated through the annihilation of dark matter particles. If instead we conclude that the source of these gamma-rays is astrophysical in origin, this spectrum will constitute a background for future dark matter searches using gamma-rays from th…
A brief review of the indirect detection signatures of dark matter is given. In particular, detection methods of dark matter particle annihilation to antimatter and gamma-rays are reviewed. With the GLAST satellite soon to be launched, a crucial window in the energy range of a few GeV up to 300 GeV will open. The good angular and energy resolution of the instrument means that structures predicted by cold dark matter models can be searched for. Large, currently planned ground-based imaging Cherenkov telescope arrays, may further improve the limits, or discover a signal, if the current understan…
The diffuse Galactic $γ$-rays from EGRET observation shows excesses above 1 GeV in comparison with the expectations from conventional Galactic cosmic ray (CR) propagation model. In the work we try to solve the "GeV excess" problem by dark matter (DM) annihilation in the frame of supersymmetry (SUSY). Compared with previous works, there are three aspects improved in this work: first, the direction-independent "boost factor" for diffuse $γ$-rays from dark matter annihilation (DMA) is naturally reproduced by taking the DM substructures into account; second, there is no need for renormalization of…
Analytical calculations and recent numerical experiments have shown that a sizable of the mass in our Galaxy is in a form of clumpy, virialized substructures that, according to \cite{dms:05}, can be as light as $10^{-6} \msun$. In this work we estimate the gamma-rays flux expected from dark matter annihilation occurring within these minihalos, under the hypothesis that the bulk of dark matter is composed by neutralinos. We generate mock sky maps showing the angular distribution of the expected gamma-ray signal. We compare them with the sensitivities of satellite-borne experiments such as GLAST…
In this work we develop a new propagation model for the Galactic cosmic rays based on the GALPROP code, including contributions from dark matter annihilation. The model predicts compatible Galactic diffuse $γ$ ray spectra with EGRET data in all sky regions. It also gives consistent results of the diffuse $γ$ ray longitude and latitude distributions. Further the results for B/C, $^{10}$Be/$^9$Be, proton, electron and antiproton spectra are also consistent with cosmic ray measurements. In the model we have taken a universal proton spectrum throughout the Galaxy without introducing large fluctuat…
The EGRET excess of diffuse Galactic gamma rays shows all the key features of dark matter annihilation (DMA) for a WIMP mass in the range 50-100 GeV, especially the distribution of the excess is compatible with a standard halo profile with some additional ringlike substructures at 4 and 13 kpc from the Galactic centre. These substructures coincide with the gravitational potential well expected from the ring of dust at 4 kpc and the tidal stream of dark matter from the Canis Major satellite galaxy at 13 kpc, as deduced from N-body simulations fitting to the Monoceros ring of stars. Strong indep…
We consider the possibility that ultra-high energy cosmic rays originate from the annihilation of relic superheavy dark-matter particles. We find that a cross section of <sigma_A v> ~ 10^{-26}cm^2 (M_X/10^{12}GeV)^{3/2} is required to account for the observed rate of super-GZK events if the superheavy dark matter follows a Navarro-Frenk-White density profile. This would require extremely large-l contributions to the annihilation cross section. We also calculate the possible signature from annihilation in sub-galactic clumps of dark matter and find that the signal from sub-clumps dominates and …
We study the prospects for detecting gamma-rays from Dark Matter (DM) annihilations in enhancements of the DM density (mini-spikes) around intermediate-mass black holes with masses in the range $10^2 \lsim M / \msun \lsim 10^6$. Focusing on two different IMBH formation scenarios, we show that, for typical values of mass and cross section of common DM candidates, mini-spikes, produced by the adiabatic growth of DM around pregalactic IMBHs, would be bright sources of gamma-rays, which could be easily detected with large field-of-view gamma-ray experiments such as GLAST, and further studied with …
In light of the mounting evidence that the highest energy cosmic rays are dominated by protons and not gamma-rays, we discuss the prospect that these cosmic rays are generated in the decay or annihilation of superheavy relic particles. We calculate the high energy neutrino spectrum which results and normalize our results to the ultra-high energy cosmic ray spectrum. We show that most scenerios are already constrained by present limits placed by the AMANDA experiment.
We calculate the flux of high energy gamma-rays from annihilation of neutralino dark matter in the centre of the Milky Way and the three nearest dwarf spheroidals (Sagittarius, Draco and Canis Major), using realistic models of the dark matter distribution.
Positron and electron cosmic rays provide a complementary way to study the galactic environment. The actual cosmic rays experiments, for instance PAMELA and HEAT, have presented very exciting results in this field. The observed positron fraction appears larger than the actual theoretical predictions for energies larger than 10 GeV. The indirect evidences of Dark Matter in connection with Beyond the Standard Model theories would suggest the existence of an extra contribution present in the cosmic ray signal. We study and calculate the positron signal produced by the annihilation of a generic Da…
The detection of gamma-rays from dark matter (DM) annihilation is among the scientific goals of the Fermi Large Area Telescope (formerly known as GLAST) and Cherenkov telescopes. In this paper we investigate the existence of realistic chances of such a discovery selecting some nearby dwarf spheroidal galaxies (dSph) as a target. We study the detectability with the Fermi-LAT of the gamma-ray flux from DM annihilation in Draco, Ursa Minor, Carina, and Sextans, for which the state-of-art DM density profiles were available. We assume the DM is made of Weakly Interacting Massive Particles such as t…
Dark matter annihilation into charged particles is necessarily accompanied by gamma rays, produced via radiative corrections. Internal bremsstrahlung from the final state particles can produce hard gamma rays up to the dark matter mass, with an approximately model-independent spectrum. Focusing on annihilation into electrons, we compute robust upper bounds on the dark matter self annihilation cross section $<σ_A v >_{e^+e^-}$ using gamma ray data from the Milky Way spanning a wide range of energies, $\sim10^{-3} - 10^4$ GeV. We also compute corresponding bounds for the other charged leptons. W…
We evaluate the antiproton--to--proton flux ratio which can be generated by neutralino--neutralino annihilation in the galactic halo, considering the most general compositions for the relic neutralinos and modelling the neutralino local density according to its relic abundance. We find that in the case of mixed neutralino compositions this $\bar p/p$ ratio is higher than for pure higgsinos or gauginos. It is shown how the expected improvements in sensitivity for the new measurements of the $\bar p/p$ may provide very useful information, complementary to the one obtainable with other experiment…
The EGRET excess in the diffuse galactic gamma ray data above 1 GeV shows all features expected from Dark Matter WIMP Annihilation: a)it is present and has the same spectrum in all sky directions, not just in the galactic plane. b) The intensity of the excess shows the $1/r^2$ profile expected for a flat rotation curve outside the galactic disc with additionally an interesting substructure in the disc in the form of a doughnut shaped ring at 14 kpc from the centre of the galaxy. At this radius a ring of stars indicates the probable infall of a dwarf galaxy, which can explain the increase in DM…
The CACTUS experiment recently observed a gamma ray excess above 50 GeV from the direction of the Draco dwarf spheroidal galaxy. Considering that Draco is dark matter dominated the gamma rays may be generated through dark matter annihilation in the Draco halo. In the framework of the minimal supersymmetric extension of the standard model we explore the parameter space to account for the gamma ray signals at CACTUS. We find that the neutralino mass is constrained to be approximately in the range between 100 GeV ~ 400 GeV and a sharp central cuspy of the dark halo profile in Draco is necessary t…
We investigate the prospects of detecting weakly interacting massive particle (WIMP) dark matter by measuring the contribution to the extragalactic gamma-ray radiation induced, in any dark matter halo and at all redshifts, by WIMP pair annihilations into high-energy photons. We perform a detailed analysis of the distinctive spectral features of this signal, recently proposed in a short letter by three of the authors, with emphasis on the signature due to monochromatic gamma-ray yields: the combined effect of cosmological redshift and absorption along the line of sight produces sharp bumps, pea…
Motivated by the interpretation of the recent results on the TeV gamma radiation from the Galactic center, including the new 2004 HESS data, as a by-product of dark matter particles annihilations, we address the question of the largest possible neutralino masses and pair annihilation cross sections in supersymmetric models. Extending the parameter space of minimal models, such as the mSUGRA and the mAMSB scenarios, to general soft SUSY breaking Higgs masses gives access to the largest possible pair annihilation rates, corresponding to resonantly annihilating neutralinos with maximal gaugino-hi…
Recent advances in N-body simulations of cold dark matter halos point to a substantial density enhancement near the center. This means that, e.g., the $γ$ ray signals from neutralino dark matter annihilations would be significantly enhanced compared to old estimates based on an isothermal sphere model with large core radius. Another important development concerns new detectors, both space- and ground-based, which will cover the window between 50 and 300 GeV where presently no cosmic $γ$-ray data are available. Thirdly, new calculations of the $γ$-ray line signal (a sharp spike of $10^{-3}$ rel…
For some time, the Draco dwarf spheroidal galaxy has garnered interest as a possible source for the indirect detection of dark matter. Its large mass-to-light ratio and relative proximity to the Earth provide favorable conditions for the production of detectable gamma rays from dark matter self-annihilation in its core. The Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) is an air-shower Cherenkov telescope located in Albuquerque, NM capable of detecting gamma rays at energies above 100 GeV. We present the results of the STACEE observations of Draco during the 2005-2006 observing …
We consider electroweak singlet dark matter with a mass comparable to the Higgs mass. The singlet is assumed to couple to standard matter through a perturbative coupling to the Higgs particle. The annihilation of a singlet with a mass comparable to the Higgs mass is dominated by proximity to the W, Z and Higgs peaks in the annihilation cross section. We find that the continuous photon spectrum from annihilation of a perturbatively coupled singlet in the galactic halo can reach a level of several per mil of the EGRET diffuse gamma ray flux.
[Abridged]. We take advantage of the galaxy-like 3D dark matter map extracted from the HORIZON Project results to calculate the positron and antiproton fluxes from dark matter annihilation, in a model-independent approach as well as for dark matter particle benchmarks relevant at the LHC scale (from supersymmetric and extra-dimensional theories). Such a study is dedicated to a better estimate of the theoretical uncertainties affecting predictions, while the PAMELA and GLAST satellites are currently taking data which will soon provide better observational constraints. We discuss the predictions…
Excesses of Galactic gamma rays in the 1-100 GeV region observed by EGRET and by WMAP have been interpreted as signals of dark matter (LSP) annihilation. We argue that the excess of TeV gamma rays from the Galactic center observed by H.E.S.S. signals a heavier dark matter component with a very small relic density.
The flat rotation curve obtained for the outer star clusters of the Large Magellanic Cloud is suggestive of an LMC dark matter halo. From the composite HI and star cluster rotation curve, I estimate the parameters of an isothermal dark matter halo added to a `maximum disk.' I then examine the possibility of detecting high energy gamma-rays from non-baryonic dark matter annihilations in the central region of the Large Magellanic Cloud.
In this paper we consider dark matter particle annihilation in the gravitational field of black holes. We obtain exact distribution function of the infalling dark matter particles, and compute the resulting flux and spectra of gamma rays coming from the objects. It is shown that the dark matter density significantly increases near a black hole. Particle collision energy becomes very high affecting relative cross-sections of various annihilation channels. We also discuss possible experimental consequences of these effects.
Dark matter annihilation has been proposed to explain the TeV gamma rays observed from the Galactic Center. We study constraints on this hypothesis coming from the mass profile around the Galactic Center measured by observing stellar dynamics. We show that for current particle models, the constraints on the dark matter density profile from measurements of mass by infrared observations are comparable to the constraints from the measurements of the TeV source extension.
The neutralino, the lightest stable supersymmetric particle, is a strong theoretical candidate for the missing astronomical "dark matter". Depending on their annihilation cross section, relic neutralinos from early formation of the Universe trapped in orbits around massive objects may currently be annihilating at measurable rates. The Minimal Supersymmetric extension of the Standard Model predicts that the gamma rays emerging from one of the annihilation modes will give a distinct monochromatic signal with energy between 100GeV and 10TeV, depending on the neutralino mass. An additional "contin…
We discuss the gamma-ray signal from dark matter annihilation in our Galaxy and in external objects, namely the Large Magellanic Cloud, the Andromeda Galaxy (M31) and M87. We derive predictions for the fluxes in a low energy realization of the Minimal Supersymmetric Standard Model and compare them with current data from EGRET, CANGAROO-II and HEGRA and with the capabilities of new-generation satellite-borne experiments, like GLAST, and ground-based Cerenkov telescopes, like VERITAS. We find fluxes below the level required to explain the possible indications of a gamma-ray excess shown by CANGA…
A number of signals involving charged cosmic rays and high-energy photons have been interpreted as being due to annihilating dark matter. This article provides an overview of the experimental evidence and discusses in particular detections of antiprotons and positrons in the cosmic radiation, the diffuse gamma-ray emission between 10 MeV and 100 GeV from the Milky Way, and the 511 keV annihilation radiation and the flux of very high-energy photons (>100 GeV) from the Galactic Centre.
The EGRET excess in the diffuse galactic gamma ray data above 1 GeV shows all the features expected from Dark Matter WIMP Annihilation: a)it is present and has the same spectrum in all sky directions, not just in the galactic plane. b) The intensity of the excess shows the $1/r^2$ profile expected for a flat rotation curve outside the galactic disc with additionally an interesting substructure in the disc in the form of a doughnut shaped ring at 14 kpc from the centre of the galaxy. At this radius a ring of stars indicates the probable infall of a dwarf galaxy, which can explain the increase i…
If dark matter (DM), which is considered to constitute most of the mass of galaxies, is made of supersymmetric (SUSY) particles, the centers of galaxies should emit gamma-rays produced by their self-annihilation. We present accurate estimates of continuum gamma-ray fluxes due to neutralino annihilation in the central regions of the Milky Way. We use detailed models of our Galaxy, which satisfy available observational data, and include some important physical processes, which were previously neglected. Our models predict that spatially extended annihilation signal should be detected at high con…
The dwarf spheroidal galaxy Draco has long been considered likely to be one of the brightest point sources of gamma-rays generated through dark matter annihilations. Recent studies of this object have found that it remains largely intact from tidal striping, and may be more massive than previously thought. In this article, we revisit Draco as a source of dark matter annihilation radiation, with these new observational constraints in mind. We discuss the prospects for the experiments MAGIC and GLAST to detect dark matter in Draco, as well as constraints from the observations of EGRET. We also d…
The diffuse galactic EGRET gamma ray data show a clear excess for energies above 1 GeV in comparison with the expectations from conventional galactic models. The excess is seen with the same spectrum in all sky directions, as expected for Dark Matter (DM) annihilation. This hypothesis is investigated in detail. The energy spectrum of the excess is used to limit the WIMP mass to the 50-100 GeV range, while the skymaps are used to determine the halo structure, which is consistent with a triaxial isothermal halo with additional enhancement of Dark Matter in the disc. The latter is strongly correl…
The GLAST LAT Collaboration is one among several experimental groups, covering a wide range of approaches, pursuing the search for the nature of dark matter. The GLAST LAT has the unique ability to find new sources of high energy gamma radiation emanating directly from WIMP annihilations in situ in the universe. Using it's wide band spectral and full sky spatial capabilities, the GLAST LAT can form "images" in high energy gamma-rays of dark matter substructures in the gamma-ray sky. We describe a preliminary feasibility study for indirect detection of Milky Way dark matter satellites using the…
Dwarf Spheroidal galaxies are amongst the best targets to search for a Dark Matter annihilation signal. The annihilation of WIMPs in the center of Sagittarius dwarf spheroidal (Sgr dSph) galaxy would produce high energy gamma-rays in the final state. Observations carried out with the H.E.S.S. array of Imaging Atmospheric Cherenkov telescopes are presented. A careful modelling of the Dark Matter halo profile of Sgr dwarf was performed using latest measurements on its structural parameters. Constraints on the velocity-weighted cross section of Dark Matter particles are derived in the framework o…
We will describe the prospects for detecting gamma-rays from WIMP's annihilation in the Galactic Center and we compare this search with the possibilities at LHC and with space antimatter experiments like PAMELA.
