Implications of hydrodynamical simulations for the interpretation of direct dark matter searches

In recent years, realistic hydrodynamical simulations of galaxies like the Milky Way have become available, enabling a reliable estimate of the dark matter density and velocity distribution in the Solar neighborhood. We review here the status of hydrodynamical simulations and their implications for the interpretation of direct dark matter searches. We focus in particular on: the criteria to identify Milky Way-like galaxies; the impact of baryonic physics on the dark matter velocity distribution; the possible presence of substructures like clumps, streams, or dark disks; and on the implications for the direct detection of dark matter with standard and non-standard interactions.Comment: 31 pages, 7 figures, 3 tables; v2: added Sec. 6.2 and Fig. 3, version accepted for publication in IJMP

Testing modified Newtonian dynamics in the Milky Way

Modified Newtonian dynamics (MOND) is an empirical theory originally proposed to explain the rotation curves of spiral galaxies by modifying the gravitational acceleration, rather than by invoking dark matter. Here,we set constraints on MOND using an up-to-date compilation of kinematic tracers of the Milky Way and a comprehensive collection of morphologies of the baryonic component in the Galaxy. In particular, we find that the so-called "standard" interpolating function cannot explain at the same time the rotation curve of the Milky Way and that of external galaxies for any of the baryonic models studied, while the so-called "simple" interpolating function can for a subset of models. Upcoming astronomical observations will refine our knowledge on the morphology of baryons and will ultimately confirm or rule out the validity of MOND in the Milky Way. We also present constraints on MOND-like theories without making any assumptions on the interpolating function.Comment: 6 pages, 3 figure

Indirect Detection of Kaluza-Klein Dark Matter

We investigate prospects for indirect detection of Kaluza--Klein dark matter, focusing on the annihilation radiation of the first Kaluza--Klein excitation of the Hypercharge gauge boson $B^{(1)}$ in the Galactic halo, in particular we estimate neutrino, gamma-ray and synchrotron fluxes. Comparing the predicted fluxes with observational data we are able to constrain the $B^{(1)}$ mass (and therefore the compactification scale). The constraints depend on the specific model adopted for the dark matter density profile. For a NFW profile the analysis of synchrotron radiation puts a lower bound on the $B^{(1)}$ mass of the order of $\simeq 300$ GeV.Comment: 8 pages, 9 figures, version accepted for publication in PR

Dynamical constraints on the dark matter distribution in the Milky Way

An accurate knowledge of the dark matter distribution in the Milky Way is of crucial importance for galaxy formation studies and current searches for particle dark matter. In this paper we set new dynamical constraints on the Galactic dark matter profile by comparing the observed rotation curve, updated with a comprehensive compilation of kinematic tracers, with that inferred from a wide range of observation-based morphologies of the bulge, disc and gas. The generalised Navarro-Frenk-White (NFW) and Einasto dark matter profiles are fitted to the data in order to determine the favoured ranges of local density, slope and scale radius. For a representative baryonic model, a typical local circular velocity of 230 km/s and a distance of the Sun to the Galactic centre of 8 kpc, we find a local dark matter density of 0.420+0.021-0.018 (2 sigma) +- 0.025 GeV/cm^3 (0.420+0.019-0.021 (2 sigma) +- 0.026 GeV/cm^3) for NFW (Einasto), where the second error is an estimate of the systematic due to baryonic modelling. Apart from the Galactic parameters, the main sources of uncertainty inside and outside the solar circle are baryonic modelling and rotation curve measurements, respectively. Upcoming astronomical observations are expected to reduce all these uncertainties substantially over the coming years.Comment: 10 pages, 5 figures, 2 tables, matches published versio

Gamma-Rays from Decaying Dark Matter

We study the prospects for detecting gamma-rays from decaying Dark Matter (DM), focusing in particular on gravitino DM in R-parity breaking vacua. Given the substantially different angular distribution of the predicted gamma-ray signal with respect to the case of annihilating DM, and the relatively poor (of order 0.1$^\circ$) angular resolution of gamma-ray detectors, the best strategy for detection is in this case to look for an exotic contribution to the gamma-ray flux at high galactic latitudes, where the decaying DM contribution would resemble an astrophysical extra-galactic component, similar to the one inferred by EGRET observations. Upcoming experiments such as GLAST and AMS-02 may identify this exotic contribution and discriminate it from astrophysical sources, or place significant constraints on the mass and lifetime of DM particles.Comment: 15 pages, 5 figures, LaTeX with iopart.cls. Minor changes, typos corrected and references added/updated. Version accepted for publication in JCA