WIMP Dark Matter Searches in Reticulum II Using MeerKAT

Abstract

In the last decade radio astronomy has emerged as a powerful technique for detecting signatures of Weakly Interacting Massive Particles (WIMPs). Dwarf spheroidal galaxies (dSphs) are particularly promising targets for these searches due to their substantial dark matter (DM) dominance and minimal baryonic background emission. In this study, we utilize the exceptional sensitivity of the MeerKAT radio telescope to search for synchrotron emission from WIMP annihilation/decay in the nearby Reticulum II dSph. Through rigorous data reduction and self-calibration, we establish constraints on WIMP properties that improve upon previous radio studies, demonstrating the potential of MeerKAT and next-generation radio telescopes in exploring increasing swathes of the WIMP parameter space.

Figures (9)

• Figure 1: Radial brightness profiles computed for a few WIMP masses annihilating into $b\bar{b}$, $\tau^+\tau^-$, and $\mu^+\mu^-$ assuming uniform (left), and self-confined (right) magnetic fields. The profiles for the self-confined magnetic field assumption were computed for cross-sections corresponding to the limit at that mass, as the cross-section determines the level of turbulence and thus the profile shape.
• Figure 2: Radial brightness profiles computed for a few WIMP masses annihilating into $b\bar{b}$, $\tau^+\tau^-$, and $\mu^+\mu^-$ assuming an exponentially decaying magnetic field.
• Figure 3: Radial brightness profiles computed for a few WIMP masses decaying into $b\bar{b}$, $\tau^+\tau^-$, and $\mu^+\mu^-$ assuming a uniform magnetic field.
• Figure 4: Final image of the Ret II field: Imaged using WSClean with Briggs (robust = 0) weighting (left) and PyBDSF residual map (final science image) (right). The shaded, circled region is the excluded region due to poor calibration.
• Figure 5: Distribution of residual pixel values (top panel) and radial brightness profile (bottom panel) for Ret II. The plots illustrate the behavior of the residuals: the pixel values follow a Gaussian distribution centered on zero, and the radial profile is consistent with noise and showing no obvious extended emission attributable to DM. Error bars represent the standard deviation of the mean ($\sigma/\sqrt{N_{\rm beams}}$) where, $N_{\rm beams}$ is the number of independent beams in each annulus and $\sigma$ is the standard deviation in the annulus.