Neutralino Dark Matter from Indirect Detection Revisited

TL;DR

This paper analyzes indirect detection prospects for neutralino dark matter, focusing on non-thermally produced winos with large annihilation cross sections. Using cosmic-ray propagation models and canonical DM density profiles, it computes signals across positrons, antiprotons, synchrotron, and gamma rays, and examines their compatibility with HEAT/AMS-01 data and upcoming PAMELA/GLAST observations. It derives anti-proton and synchrotron bounds and discusses how positron and gamma-ray channels could reveal a non-thermal wino, highlighting the importance of the DM halo profile and astrophysical uncertainties. The work also discusses implications for LHC searches and direct detection, noting that Higgsino admixtures can enhance cross sections and that collider signatures depend on the SUSY mass spectrum.

Abstract

We revisit indirect detection possibilities for neutralino dark matter, emphasizing the complementary roles of different approaches. While thermally produced dark matter often requires large astrophysical "boost factors" to observe antimatter signals, the physically motivated alternative of non-thermal dark matter can naturally provide interesting signals, for example from light wino or Higgsino dark matter. After a brief review of cosmic ray propagation, we discuss signals for positrons, antiprotons, synchrotron radiation and gamma rays from wino annihilation in the galactic halo, and examine their phenomenology. For pure wino dark matter relevant to the LHC, PAMELA and GLAST should report signals.

Figures (8)

• Figure 1: The diffusion zone (cylinder) is taken to have a height $2L$, with $L$ in the range of 4-12 kpc Strong:1999su, whereas the radial direction is taken as $R_h = 20$ kpc (see figure 1). Most of the interstellar gas is confined to the galactic plane at $z=0$, which represents a slice through the cylinder and has a height of $2h=100$ pc. Our solar system is then located in this plane at a distance of around $r_0=8.5$ kpc from the galactic center. All of this is enveloped by a spherically symmetric dark matter halo.
• Figure 2: The flux in anti-protons for varying neutralino mass ($m_{\chi}=150,200,300$ GeV). We have taken a diffusion zone height of $L=4$ kpc.
• Figure 3: The flux in anti-protons for varying height of the diffusion zone cylinder with and NFW dark matter profile. We have taken a $m_{\chi}=200$ GeV wino.
• Figure 4: The flux of anti-protons is shown using different dark matter distributions. We have fixed $L=4$ kpc, and the wino mass to be $m_{X} =200$ GeV. Since the anti-protons may sample the inner region of the galaxy, the cuspiness of the profile does effect the anti-proton flux.
• Figure 5: Power radiated into 22 GHz as a function of electron energy for different values of the galactic magnetic field. Notice that for energies below 5 GeV, there is negligible radiation.