5 research outputs found
Gamma ray and Neutrino fluxes from a cosmological dark matter simulation
In this paper, we estimate the gamma-ray and neutrino fluxes coming from dark
matter annihilation in a Milky Way framework provided by a recent N-BODY
HORIZON simulation. We first study the characteristics of the simulation and
highlight the mass distribution within the galactic halo. The general dark
matter density has a typical power law for large radii, but the inner
behaviour is poorly constrained below the resolution of the simulation ( pc). We identify clumps and subclumps and analyze their distribution, as
well as their internal structure. Inside the clumps, the power law is rather
universal, in the outer part with again strong uncertainties for
smaller radii, especially for light clumps. We show a full-sky map of the
astrophysical contribution to the gamma-ray or neutrino fluxes in this N-body
framework. Using quite model independent and general assumptions for the high
energy physics part, we evaluate the possible absolute fluxes and show some
benchmark regions for the experiments GLAST, EGRET, and a km3 size extension of
ANTARES like the KM3NeT project. While individual clumps seem to be beyond
detection reach, the galactic center region is promising and GLAST could be
sensitive to the geometry and the structure of its dark matter distribution.
The detection by a km3 version of ANTARES is, however, more challenging due to
a higher energy threshold. We also point out that the lack of resolution leaves
the inner structure of subhalos poorly constrained. Using the same clump
spectrum and mass fraction, a clump luminosity boost of order ten can be
achieved with a steeper profile in the inner part of the sub-halos.Comment: 15 pages, 8 figure
Halo Geometry and Dark Matter Annihilation Signal
We study the impact of the halo shape and geometry on the expected weakly
interacting massive particle (WIMP) dark matter annihilation signal from the
galactic center. As the halo profile in the innermost region is still poorly
constrained, we consider different density behaviors like flat cores, cusps and
spikes, as well as geometrical distortions. We show that asphericity has a
strong impact on the annihilation signal when the halo profile near the
galactic center is flat, but becomes gradually less significant for cuspy
profiles, and negligible in the presence of a central spike. However, the
astrophysical factor is strongly dependent on the WIMP mass and annihilation
cross-section in the latter case.Comment: 5 pages, 4 figures, PR
Dark Matter Direct Detection Signals inferred from a Cosmological N-body Simulation with Baryons
We extract at redshift z=0 a Milky Way sized object including gas, stars and
dark matter (DM) from a recent, high-resolution cosmological N-body simulation
with baryons. Its resolution is sufficient to witness the formation of a
rotating disk and bulge at the center of the halo potential. The phase-space
structure of the central galactic halo reveals the presence of a dark disk
component, that is co-rotating with the stellar disk. At the Earth's location,
it contributes to around 25% of the total DM local density, whose value is
rho_DM ~ 0.37 GeV/cm^3. The velocity distributions also show strong deviations
from pure Gaussian and Maxwellian distributions, with a sharper drop of the
high velocity tail.
We give a detailed study of the impact of these features on the predictions
for DM signals in direct detection experiments. In particular, the question of
whether the modulation signal observed by DAMA is or is not excluded by limits
set by other experiments (CDMS, XENON and CRESST...) is re-analyzed and
compared to the case of a standard Maxwellian halo, in both the elastic and the
inelastic scattering scenarios. We find that the compatibility between DAMA and
the other experiments is improved. In the elastic scenario, the DAMA modulation
signal is slightly enhanced in the so-called channeling region, as a result of
several effects. For the inelastic scenario, the improvement of the fit is
mainly attributable to the departure from a Maxwellian distribution at high
velocity.Comment: 39 page
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 . In addition, the
recently improved upper bound on 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