A search for annihilating dark matter in 47 Tucanae and Omega Centauri

A plausible formation scenario for the Galactic globular clusters 47 Tuc and Omega Cen is that they are tidally stripped remnants of dwarf galaxies, in which case likely to have retained a fraction their dark matter cores. In this study, we used ultra-wide band receiver on Parkes telescope (Murriyang) place upper limits annihilation rate exotic Light Dark Matter particles (X) via XX/$e^+e^-$ channel using measurements recombination positronium (Ps). This an extension technique previously search Ps Centre. However, by stacking spectral data at multiple line frequencies, been able improve sensitivity. Our resulted 3-sigma flux density (recombination rate) 1.7 mJy (1.4x10$^{43}$ s$^{-1}$) 0.8 (1.1x10$^{43}$ Cen, respectively. Within beam cluster distances, varies from 10 23 pc depending frequency line, calculate mass rms <1.2-1.3x10$^5$ fn$^{-0.5}$ (mX/MeV c$^{-2}$) solar masses <48-54 pc$^{-3}$ clusters, where fn=Rn/Rp ratio transitions annihilations, estimated be 0.01. The radio suggest that, fiducial dark/luminous 0.05, any contribution small unless cross section <7.9x10$^{-28}$ c$^{-2}$)$^2$ cm$^3$ s$^{-1}$. Owing compactness proximity archival 511-keV even tighter than permitted CMB anisotropies, <8.6x10$^{-31}$ substantially previous Milky Way.