1 / 16

Indirect Detection Of Dark Matter

Indirect Detection Of Dark Matter. D.T. Cumberbatch. Rotation Curves of spiral galaxies:. M/L ratio. Galaxy clusters:. Proper motion. X-ray emissions from hot gas. Gravitational lensing. 2dFGRS. Abell 1689, HST. Large-scale structure. Anisotropies in the CMB. WMAP.

kellsie
Download Presentation

Indirect Detection Of Dark Matter

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Indirect Detection Of Dark Matter D.T. Cumberbatch

  2. Rotation Curves of spiral galaxies: • M/L ratio Galaxy clusters: • Proper motion • X-ray emissions from hot gas • Gravitational lensing 2dFGRS Abell 1689, HST Large-scale structure Anisotropies in the CMB WMAP Motivation for Dark Matter

  3. characteristic of EW interactions What is the Dark Matter made of? • Weakly Interacting Massive Particles (WIMPS) • Lightest Neutralino • Stable LSP of SUSY models which conserve R-Parity … AND MANY MORE!!! (e.g. LDM, Gravitinos, Axions, KK bosons, …)

  4. Direct Detection • Measure phonon, charge or light signals produced from elastic scattering of WIMPS with a nuclear target • DAMA, CDMS, EDELWEISS, ZEPLIN, CRESST • Indirect Detection • Measure excess in diffuse antiparticle flux from DM annihilations • HEAT, HESS, EGRET, BESS DM Detection Methods Two Complementary Methods:

  5. Background (Protheroe, 1984) EXCESS! A Positron Excess Astrophysical Sources? • Supernovae Type 1a • Massive Wolf-Rayet stars Astrophysical sources are insufficient!!!

  6. Continuum positrons from cascades involving and For , (solid) dominates and (dotted) less so For : (dashed) occur, producing a more complicated spectrum Positron Production from annihilation • Final injection spectrum depends on mass and decay modes:

  7. Antiprotons Positrons (Baltz et al. 2001) We require Substructure!!! Annihilation Rate annihilation within a smooth halo • Smooth Halo:

  8. “Bottom-up” hierarchical structure formation • Total flux from DMCs strongly depends upon and (Diemand et al. Nature, 433, 389 (2005)) Assuming that the DMC distribution traces the halo density with ahalo-to-halo scatter of 4 DM Substructure • Standard model assumes that structure originated from quantum fluctuations during inflation • Subhalo Population = (Constructive Merging) + (Tidal Destruction)

  9. We assume that all clumps will currently possess a fraction f (0< f <1) of its mass at z=26, since (Zhao et al. 2005) DM Substructure • But the simulation was terminated at z=26 • We must account for subsequent tidal stripping by stellar encounters during orbits • We adopt NFW profiles for the DMCs (~consistent with simulation data) The amplification of the antiparticle flux from clumps is then:

  10. Energy loss rate Assuming a constant B-field: Diffusion Constant Source Term Proportional to halo annihilation rate per unit vol. Cosmic Ray Propagation • Charged particles diffuse through ISM • Scattering off galactic B-field, CMB radiation and starlight result in energy losses • Diffusion can be well-approximated to a random walk

  11. Manipulate into an inhomogeneous ( “heat” ) equation (Baltz et al. 1998) • We can solve for by constructing the Green’s function Cosmic Ray Propagation • We solve for the steady-state solution

  12. Cosmic Ray Propagation • We solve the inhomogeneous equation, using method of Fourier Transforms, for a mono-energetic, point source (of energy and position): z • Assume uniform cylindrical diffusion zone: Free Escape Zone • BCs require at (Webber et al. 1971) 2L Diffusion Zone Free Escape Zone • Using principle of superposition (Baltz et al. 1998): Boundary Conditions?

  13. Cosmic Ray Propagation • Calculate PF using for 4 benchmark MSSM models • Calculate PF for and 1.6 or 3 • left as a free parameter • Finally, the solution for the local differential flux (z=0, r=8 kpc) is

  14. Positron Fraction

  15. Positron Fraction • We require: (for up to 90% stripping) • Canonical value: • Profumo indicates how canonical value can be grossly violated with at possible • However these models require co-annihilations and resonant annihilations making them more contrived

  16. Conclusion + Further Work • To improve our analysis we can select LSPs based on a more stringent scan of the entire MSSM parameter space Considering the errors in the halo DMC abundance, some models are clearly permitted, with preferential selection towards lighter LSPs, even when considering the effects of tidal destruction • Cross-reference results on PF with an analysis of cosmic antiprotons, antideuterons, gamma rays, etc.

More Related