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The question of the nature of the dark matter in the Universe remains one of the most outstanding unsolved problems in basic science. One of the best motivated particle physics candidates is the lightest supersymmetric particle, assumed to be the lightest neutralino -a linear combination of the supersymmetric partners of the photon, the Z boson and neutral scalar Higgs particles. Here we describe DarkSUSY, a publicly-available advanced numerical package for neutralino dark matter calculations. In DarkSUSY one can compute the neutralino density in the Universe today using precision methods which include resonances, pair production thresholds and coannihilations. Masses and mixings of supersymmetric particles can be computed within DarkSUSY or with the help of external programs such as FeynHiggs, ISASUGRA and SUSPECT. Accelerator bounds can be checked to identify viable dark matter candidates. DarkSUSY also computes a large variety of astrophysical signals from neutralino dark matter, such as direct detection in low-background counting experiments and indirect detection through antiprotons, antideuterons, gamma-rays and positrons from the Galactic halo or high-energy neutrinos from the center of the Earth or of the Sun. Here we describe the physics behind the package. A detailed manual will be provided with the computer package.

If cold dark matter is present at the galactic center, as in current models of the dark halo, it is accreted by the central black hole into a dense spike. Particle dark matter then annihilates strongly inside the spike, making it a compact source of photons, electrons, positrons, protons, antiprotons, and neutrinos. The spike luminosity depends on the density profile of the inner halo: halos with finite cores have unnoticeable spikes, while halos with inner cusps may have spikes so bright that the absence of a detected neutrino signal from the galactic center already places interesting upper limits on the density slope of the inner halo. Future neutrino telescopes observing the galactic center could probe the inner structure of the dark halo, or indirectly find the nature of dark matter.The evidence is mounting for a massive black hole at the galactic center. Ghez et al. [1] have confirmed and sharpened the Keplerian behavior of the star velocity dispersion in the inner 0.1 pc of the galaxy found by Eckart and Genzel [2]. These groups estimate the mass of the black hole to be M = 2.6 ± 0.2 × 10 6 M . If cold dark matter is present at the galactic center, as in current models of the dark halo, it is redistributed by the black hole into a cusp. We call it the central 'spike,' to avoid confusion with the inner halo cusp favored by present N-body simulations of galaxy formation [3]. If cold dark matter contains neutral elementary particles that can annihilate with each other, like the supersymmetric neutralino, the annihilation rate in the spike is strongly increased as it depends on the square of the matter density. The steep spike profile, with index ≥ 3/2, then implies that most of the annihilations take place at the inner radius of the spike, determined either by self-annihilation or by capture into the black hole.Of the annihilation end-products, neutrinos escape the spike and propagate to us undisturbed. Current limits on the neutrino emission from the galactic center place upper limits on the slope of the inner halo. Future neutrino telescopes may improve on these limits or bring information on the nature of dark matter. I. ADIABATIC SPIKE AROUND THE CENTRAL BLACK HOLEWe find the dark matter density profile in the region where the black hole dominates the gravitational potential. From the data in [1,2], this is the region r < ∼ R M 0.2 pc. Other masses (the central star cluster, for example) also influence the dark matter distribution, but since they make the gravitational potential deeper, their effect is to increase the central dark matter density and the annihilation signals.We work under the assumption that the growth of the black hole is adiabatic. This assumption is supported by the collisionless behavior of particle dark matter. We can find the final density after black hole formation from the final phase-space distribution f (E , L ) aswithWe have neglected the contribution from unbound orbits (E > 0). The lower limit of integration L c , and the second factor in E m , are introduced to eliminate the ...

We evaluate the relic density of the lightest neutralino, the lightest supersymmetric particle, in the Minimal Supersymmetric extension of the Standard Model (MSSM). For the first time, we include all coannihilation processes between neutralinos and charginos for any neutralino mass and composition. We use the most sophisticated routines for integrating the cross sections and the Boltzmann equation. We properly treat (sub)threshold and resonant annihilations. We also include one-loop corrections to neutralino masses. We find that coannihilation processes are important not only for light higgsino-like neutralinos, as pointed out before, but also for heavy higgsinos and for mixed and gaugino-like neutralinos. Indeed, coannihilations should be included whenever |µ| ∼ < 2|M1|, independently of the neutralino composition. When |µ| ∼ |M1|, coannihilations can increase or decrease the relic density in and out of the cosmologically interesting region. We find that there is still a window of light higgsino-like neutralinos that are viable dark matter candidates and that coannihilations shift the cosmological upper bound on the neutralino mass from 3 to 7 TeV. *

The DAMA/NaI and DAMA/LIBRA annual modulation data, which may be interpreted as a signal for the existence of weakly interacting dark matter (WIMPs) in our galactic halo, are examined in light of null results from other experiments: CDMS, XENON10, CRESST I, CoGeNT, TEXONO, and Super-Kamiokande (Su-perK). We use the energy spectrum of the combined DAMA modulation data given in 36 bins, and include the effect of channeling. Several statistical tools are implemented in our study: likelihood ratio with a global fit and with raster scans in the WIMP mass and goodness-of-fit (g.o.f.). These approaches allow us to differentiate between the preferred (global best fit) and allowed (g.o.f.) parameter regions. It is hard to find WIMP masses and couplings consistent with all existing data sets; the surviving regions of parameter space are found here. For spin-independent (SI) interactions, the best fit DAMA regions are ruled out to the 3σ C.L., even with channeling taken into account. However, for WIMP masses of ∼8 GeV some parameters outside these regions still yield a moderately reasonable fit to the DAMA data and are compatible with all 90% C.L. upper limits from negative searches, when channeling is included. For spin-dependent (SD) interactions with proton-only couplings, a range of masses below 10 GeV is compatible with DAMA and other experiments, with and without channeling, when SuperK indirect detection constraints are included; without the SuperK constraints, masses as high as ∼20 GeV are compatible. For SD neutron-only couplings we find no parameters compatible with all the experiments. Mixed SD couplings are examined: e.g. ∼8 GeV mass WIMPs with a n = ±a p are found to be consistent with all experiments. In short, there are surviving regions at low mass for both SI and SD interactions; if indirect detection limits are relaxed, some SD proton-only couplings at higher masses also survive.