Antideuteron fluxes from dark matter annihilation in diffusion models

TL;DR

The paper assesses antideuteron fluxes from dark matter annihilation within a two-zone diffusion model, updating both secondary and primary components and detailing propagation, nuclear, and halo uncertainties. It uses the coalescence picture with $p_0\approx79$ MeV to connect antiproton spectra to antideuteron production in both hadronic and electroweak channels. Propagation uncertainties dominate the primary flux, while nuclear cross sections largely govern the secondary background, with fluxes strongly dependent on the DM density profile and halo size. The results indicate that antideuterons are a compelling indirect DM signal for low- to intermediate-mass WIMPs, and upcoming experiments such as GAPS and AMS-02 could detect signals in favorable SUSY scenarios without conflicting with current antiproton measurements.

Abstract

Antideuterons are among the most promising galactic cosmic ray-related targets for dark matter indirect detection. Currently only upper limits exist on the flux, but the development of new experiments, such as GAPS and AMS-02, provides exciting perspectives for a positive measurement in the near future. In this Paper, we present a novel and updated calculation of both the secondary and primary antideuteron fluxes. We employ a two-zone diffusion model which successfully reproduces cosmic-ray nuclear data and the observed antiproton flux. We review the nuclear and astrophysical uncertainties and provide an up to date secondary (i.e. background) antideuteron flux. The primary (i.e. signal) contribution is calculated for generic WIMPs annihilating in the galactic halo: we explicitly consider and quantify the various sources of uncertainty in the theoretical evaluations. Propagation uncertainties, as is the case of antiprotons, are sizeable. Nevertheless, antideuterons offer an exciting target for indirect dark matter detection for low and intermediate mass WIMP dark matter. We then show the reaching capabilities of the future experiments for neutralino dark matter in a variety of supersymmetric models.

Figures (17)

• Figure 1: Contribution of all nuclear channels to the $\overline{d}$ secondary flux. Dashed lines, from top to bottom refer to: p+H, p+He, He+H, He+He. Dotted lines, from top to bottom stand for: $\overline{p}$+H, $\overline{p}$+He. Solid line: sum of all the components.
• Figure 2: Dominant uncertainties on the interstellar secondary $\overline{d}$ flux. Solid lines: propagation uncertainty band. Dotted lines: nuclear uncertainty band.
• Figure 3: Antideuteron flux for a WIMP mass $m_\chi$=100 GeV annihilating into different final states: solid (black) line refers to $\bar{b}b$, dotted (red) to $\bar{u}u$, short-dashed (blue) to $WW$, long-dashed (green) line to $ZZ$. The dot-dashed (magenta) refers to $\bar{t}t$ and $m_\chi$=200 GeV. The annihilation cross section (here and in the following figures) is fixed at the value: $\langle \sigma_{\rm ann} v \rangle_{0} = 2.3 \cdot 10^{-26}$ cm$^3$ s$^{-1}$.
• Figure 4: Antideuteron flux for WIMPs of $m_\chi$=50 GeV. Dotted (black) lines refer to the interstellar flux, solid (red) lines stand for the top--of--atmosphere flux, modulated at solar minimum. For each set of curves, the three lines refer to the maximal, median and minimal propagation configurations defined in Table \ref{['table:prop']}.
• Figure 5: Uncertainty due to propagation models on the antideuteron (black solid lines) and antiproton (red dotted lines) interstellar fluxes. The WIMP mass has been fixed at the value $m_\chi$=50 GeV. For each set of curves, the three lines refer to the maximal, median and minimal propagation configurations defined in Table \ref{['table:prop']}.